A medium bomber is a military bomber aircraft designed to operate with medium-sized bombloads over medium range distances; the name serves to distinguish this type from larger heavy bombers and smaller light bombers . Mediums generally carried about two tons of bombs, compared to light bombers that carried one ton, and heavies that carried four or more.
130-483: The North American B-25 Mitchell is an American medium bomber that was introduced in 1941 and named in honor of Brigadier General William "Billy" Mitchell , a pioneer of U.S. military aviation. Used by many Allied air forces, the B-25 served in every theater of World War II , and after the war ended, many remained in service, operating across four decades. Produced in numerous variants, nearly 10,000 B-25s were built. It
260-574: A Hearing Impaired (HI) audio track may be available via headphones to better hear dialog. This choice depends on the level of hearing loss, type of hearing loss, and personal preference. Hearing aid applications are one of the options for hearing loss management. For people with bilateral hearing loss, it is not clear if bilateral hearing aids (hearing aids in both ears) are better than a unilateral hearing aid (hearing aid in one ear). For people with idiopathic sudden hearing loss, different treatment approaches have been suggested that are usually based on
390-490: A constant-dihedral, meaning the wing had a consistent, upward angle from the fuselage to the wingtip. This design caused stability problems. "Flattening" the outer wing panels just outboard of the engine nacelles nullified the problem and gave the B-25 its gull wing configuration. Less noticeable changes during this period included an increase in the size of the tail fins and a decrease in their inward tilt at their tops. NAA continued design and development in 1940 and 1941. Both
520-488: A conventional hearing test. Auditory brainstem response testing is an electrophysiological test used to test for hearing deficits caused by pathology within the ear, the cochlear nerve and also within the brainstem. A case history (usually a written form, with questionnaire) can provide valuable information about the context of the hearing loss, and indicate what kind of diagnostic procedures to employ. Examinations include otoscopy , tympanometry , and differential testing with
650-670: A difference rather than a disability . Many members of Deaf culture oppose attempts to cure deafness and some within this community view cochlear implants with concern as they have the potential to eliminate their culture. Use of the terms "hearing impaired", "deaf-mute", or "deaf and dumb" to describe deaf and hard of hearing people is discouraged by many in the deaf community as well as advocacy organizations, as they are offensive to many deaf and hard of hearing people. Human hearing extends in frequency from 20 to 20,000 Hz, and in intensity from 0 dB to 120 dB HL or more. 0 dB does not represent absence of sound, but rather
780-573: A few hundred. Some B-25s continued in service into the 1950s in training, reconnaissance, and support roles. The principal use during this period was undergraduate training of multiengine aircraft pilots slated for reciprocating engine or turboprop cargo, aerial refueling, or reconnaissance aircraft. Others were assigned to units of the Air National Guard in training roles in support of Northrop F-89 Scorpion and Lockheed F-94 Starfire operations. During its USAF tenure, many B-25s received
910-567: A group can be ascribed to age and noise exposure . The result is calculated via an algebraic equation that uses the A-weighted sound exposure level, how many years the people were exposed to this noise, how old the people are, and their sex. The model's estimations are only useful for people without hearing loss due to non-job related exposure and can be used for prevention activities. The United States Preventive Services Task Force recommends neonatal hearing screening for all newborns, as
1040-410: A hearing loss is ranked according to ranges of nominal thresholds in which a sound must be so it can be detected by an individual. It is measured in decibels of hearing loss, or dB HL. There are three main types of hearing loss: conductive hearing loss , sensorineural hearing loss , and mixed hearing loss. An additional problem which is increasingly recognised is auditory processing disorder which
1170-492: A hearing test. Hearing diagnosis using mobile application is similar to the audiometry procedure. Audiograms, obtained using mobile applications, can be used to adjust hearing aid applications. Another method for quantifying hearing loss is a speech-in-noise test. which gives an indication of how well one can understand speech in a noisy environment. Otoacoustic emissions test is an objective hearing test that may be administered to toddlers and children too young to cooperate in
1300-433: A nominal load of 8,000 pounds (3,600 kg) or more, and light bombers carried up to 2,000 lb (907 kg). These distinctions were beginning to disappear by the middle of World War II, when the average fighter aircraft could now carry a 2,000 lb (907 kg) bombload. Advances in powerplants and designs eventually allowed light bombers , tactical bombers , and later jet fighter-bombers to take over
1430-454: A person's hearing loss. Hearing loss due to chemicals starts in the high frequency range and is irreversible. It damages the cochlea with lesions and degrades central portions of the auditory system . For some ototoxic chemical exposures, particularly styrene, the risk of hearing loss can be higher than being exposed to noise alone. The effects is greatest when the combined exposure include impulse noise . A 2018 informational bulletin by
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#17327799108961560-516: A single strafing run), relative ineffectiveness against ground targets, and the substantial recoil, the 75 mm gun was sometimes removed from both G and H models and replaced with two additional .50 in (12.7 mm) machine guns as a field modification. In the new FEAF, these were redesignated the G1 and H1 series, respectively. The H series normally came from the factory mounting four fixed, forward-firing .50 in (12.7 mm) machine guns in
1690-537: A total of 464 B-25Gs. In its final version, the G-12, an interim armament modification, eliminated the lower Bendix turret and added a starboard dual gun pack, waist guns, and a canopy for the tail gunner to improve the view when firing the single tail gun. In April 1945, the air depots in Hawaii refurbished about two dozen of these and included the eight-gun nose and rocket launchers in the upgrade. The B-25H series continued
1820-473: Is a condition where a person as an immediate decrease in the sensitivity of their sensorineural hearing that does not have a known cause. This type of loss is usually only on one side (unilateral) and the severity of the loss varies. A common threshold of a "loss of at least 30 dB in three connected frequencies within 72 hours" is sometimes used, however there is no universal definition or international consensus for diagnosing idiopathic sudden hearing loss. It
1950-592: Is a consideration when deciding on a treatment approach. Globally, hearing loss affects about 10% of the population to some degree. It caused moderate to severe disability in 124.2 million people as of 2004 (107.9 million of whom are in low and middle income countries). Of these 65 million acquired the condition during childhood. At birth ~3 per 1000 in developed countries and more than 6 per 1000 in developing countries have hearing problems. Hearing loss increases with age. In those between 20 and 35 rates of hearing loss are 3% while in those 44 to 55 it
2080-432: Is a partial or total inability to hear . Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken language , and in adults it can create difficulties with social interaction and at work. Hearing loss can be temporary or permanent. Hearing loss related to age usually affects both ears and
2210-456: Is a progressive loss of ability to hear high frequencies with aging known as presbycusis . For men, this can start as early as 25 and women at 30. Although genetically variable, it is a normal concomitant of ageing and is distinct from hearing losses caused by noise exposure, toxins or disease agents. Common conditions that can increase the risk of hearing loss in elderly people are high blood pressure , diabetes ( hearing loss in diabetes ), or
2340-428: Is a yearly event to promote actions to prevent hearing damage. Avoiding exposure to loud noise can help prevent noise-induced hearing loss. 18% of adults exposed to loud noise at work for five years or more report hearing loss in both ears as compared to 5.5% of adults who were not exposed to loud noise at work. Different programs exist for specific populations such as school-age children, adolescents and workers. But
2470-635: Is an increasing concern especially in aging populations. The prevalence of hearing loss increases about two-fold for each decade increase in age after age 40. While the secular trend might decrease individual level risk of developing hearing loss, the prevalence of hearing loss is expected to rise due to the aging population in the US. Another concern about aging process is cognitive decline, which may progress to mild cognitive impairment and eventually dementia. The association between hearing loss and cognitive decline has been studied in various research settings. Despite
2600-587: Is another useful skill some develop. Access to hearing aids, however, is limited in many areas of the world. As of 2013 hearing loss affects about 1.1 billion people to some degree. It causes disability in about 466 million people (5% of the global population), and moderate to severe disability in 124 million people. Of those with moderate to severe disability 108 million live in low and middle income countries. Of those with hearing loss, it began during childhood for 65 million. Those who use sign language and are members of Deaf culture may see themselves as having
2730-548: Is associated with increased difficulties in postural control and increased prevalence of falls. The underlying causal link between the association of hearing loss and falls is yet to be elucidated. There are several hypotheses that indicate that there may be a common process between decline in auditory system and increase in incident falls, driven by physiological, cognitive, and behavioral factors. This evidence suggests that treating hearing loss has potential to increase health-related quality of life in older adults. Depression
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#17327799108962860-1024: Is cumulative; all sources of damage must be considered to assess risk. In the US, 12.5% of children aged 6–19 years have permanent hearing damage from excessive noise exposure. The World Health Organization estimates that half of those between 12 and 35 are at risk from using personal audio devices that are too loud. Hearing loss in adolescents may be caused by loud noise from toys, music by headphones, and concerts or events. Hearing loss can be inherited. Around 75–80% of all these cases are inherited by recessive genes , 20–25% are inherited by dominant genes , 1–2% are inherited by X-linked patterns, and fewer than 1% are inherited by mitochondrial inheritance . Syndromic deafness occurs when there are other signs or medical problems aside from deafness in an individual, such as Usher syndrome , Stickler syndrome , Waardenburg syndrome , Alport's syndrome , and neurofibromatosis type 2 . Nonsyndromic deafness occurs when there are no other signs or medical problems associated with
2990-473: Is defined by a frequency versus intensity graph, or audiogram, charting sensitivity thresholds of hearing at defined frequencies. Because of the cumulative impact of age and exposure to noise and other acoustic insults, 'typical' hearing may not be normal. Hearing loss is sensory, but may have accompanying symptoms: There may also be accompanying secondary symptoms: Hearing loss is associated with Alzheimer's disease and dementia . The risk increases with
3120-521: Is due to cochlear hair cell loss. In some people, particularly older people, hearing loss can result in loneliness. Hearing loss may be caused by a number of factors, including: genetics , ageing , exposure to noise , some infections , birth complications, trauma to the ear, and certain medications or toxins. A common condition that results in hearing loss is chronic ear infections . Certain infections during pregnancy, such as cytomegalovirus , syphilis and rubella , may also cause hearing loss in
3250-653: Is estimated that half of cases of hearing loss are preventable. About 60% of hearing loss in children under the age of 15 can be avoided. There are a number of effective preventative strategies, including: immunization against rubella to prevent congenital rubella syndrome , immunization against H. influenza and S. pneumoniae to reduce cases of meningitis , and avoiding or protecting against excessive noise exposure. The World Health Organization also recommends immunization against measles , mumps , and meningitis , efforts to prevent premature birth , and avoidance of certain medication as prevention. World Hearing Day
3380-432: Is generally measured by playing generated or recorded sounds, and determining whether the person can hear them. Hearing sensitivity varies according to the frequency of sounds. To take this into account, hearing sensitivity can be measured for a range of frequencies and plotted on an audiogram . Other method for quantifying hearing loss is a hearing test using a mobile application or hearing aid application, which includes
3510-512: Is hearing loss that is sustained after the acquisition of language , which can occur due to disease , trauma , or as a side-effect of a medicine. Typically, hearing loss is gradual and often detected by family and friends of affected individuals long before the patients themselves will acknowledge the disability. Post-lingual deafness is far more common than pre-lingual deafness. Those who lose their hearing later in life, such as in late adolescence or adulthood, face their own challenges, living with
3640-485: Is no longer used, development of aircraft that fulfil a 'medium bomber' mission in all but name continued and these have been employed in various post-World War II conflicts; examples include dedicated tactical bombers such as the Su-24 , Su-34 , F-111 , J-16 and F-15E which have greater payload and range capability than fighter-bombers, but less than heavier strategic bombers. Hearing loss Hearing loss
3770-415: Is not a hearing loss as such but a difficulty perceiving sound. The shape of an audiogram shows the relative configuration of the hearing loss, such as a Carhart notch for otosclerosis, 'noise' notch for noise-induced damage, high frequency rolloff for presbycusis, or a flat audiogram for conductive hearing loss. In conjunction with speech audiometry, it may indicate central auditory processing disorder, or
3900-748: Is one of the leading causes of morbidity and mortality worldwide. In older adults, the suicide rate is higher than it is for younger adults, and more suicide cases are attributable to depression. Different studies have been done to investigate potential risk factors that can give rise to depression in later life. Some chronic diseases are found to be significantly associated with risk of developing depression, such as coronary heart disease , pulmonary disease , vision loss and hearing loss. Hearing loss can contribute to decrease in health-related quality of life, increase in social isolation and decline in social engagement, which are all risk factors for increased risk of developing depression symptoms. Post-lingual deafness
4030-543: Is preventable through public health measures. Such practices include immunization , proper care around pregnancy , avoiding loud noise, and avoiding certain medications. The World Health Organization recommends that young people limit exposure to loud sounds and the use of personal audio players to an hour a day in an effort to limit exposure to noise. Early identification and support are particularly important in children. For many, hearing aids , sign language , cochlear implants and subtitles are useful. Lip reading
North American B-25 Mitchell - Misplaced Pages Continue
4160-447: Is progressive and irreversible, and there are currently no approved or recommended treatments. A few specific kinds of hearing loss are amenable to surgical treatment. In other cases, treatment is addressed to underlying pathologies, but any hearing loss incurred may be permanent. Some management options include hearing aids , cochlear implants , middle ear implants , assistive technology , and closed captioning ; in movie theaters ,
4290-455: Is the aminoglycosides (main member gentamicin ) and platinum based chemotherapeutics such as cisplatin and carboplatin . In addition to medications, hearing loss can also result from specific chemicals in the environment: metals, such as lead ; solvents , such as toluene (found in crude oil , gasoline and automobile exhaust , for example); and asphyxiants . Combined with noise, these ototoxic chemicals have an additive effect on
4420-721: The English Electric Canberra (along with its derived U.S. counterpart, the Martin B-57 ) and the Soviet Ilyushin Il-28 "Beagle". Subsequent to World War II, only the U.S. Strategic Air Command ever used the term "medium bomber" in the 1950s to distinguish its Boeing B-47 Stratojets from somewhat larger contemporary Boeing B-52 Stratofortress "heavy bombers" in bombardment wings (older B-29 and B-50 heavy bombers were also redesignated as "medium" during this period). This nomenclature
4550-669: The Henschel Hs 129B-3 and Junkers Ju 88P-1 . The B-25G's shorter nose placed the cannon breech behind the pilot, where it could be manually loaded and serviced by the navigator; his crew station was moved to a position just behind the pilot. The navigator signaled the pilot when the gun was ready and the pilot fired the weapon using a button on his control wheel. The Royal Air Force, U.S. Navy, and Soviet VVS each conducted trials with this series, but none adopted it. The G series comprised one prototype, five preproduction C conversions, 58 C series modifications, and 400 production aircraft for
4680-663: The Japanese attack on Pearl Harbor (a 16th plane which participated was forced to abort, landing in Russia, where it and the crew were initially interned). The mission gave a much-needed lift in morale to the Americans and alarmed the Japanese, who had believed their home islands to be inviolable by enemy forces. Although the amount of actual damage done was relatively minor, it forced the Japanese to divert troops for home defense for
4810-715: The Marshall Islands . The first B-25s arrived in Egypt and were carrying out independent operations by October 1942. Operations there against Axis airfields and motorized vehicle columns supported the ground actions of the Second Battle of El Alamein . Thereafter, the aircraft took part in the rest of the campaign in North Africa , the invasion of Sicily , and the advance up Italy . In the Strait of Messina to
4940-648: The National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) work together to provide standards and enforcement on workplace noise levels. The hierarchy of hazard controls demonstrates the different levels of controls to reduce or eliminate exposure to noise and prevent hearing loss, including engineering controls and personal protective equipment (PPE). Other programs and initiative have been created to prevent hearing loss in
5070-808: The Netherlands East Indies to help deter any Japanese aggression into the region. In February 1942, the British Overseas Airways Corporation agreed to ferry 20 Dutch B-25s from Florida to Australia travelling via Africa and India, and an additional 10 via the South Pacific route from California. During March, five of the bombers on the Dutch order had reached Bangalore , India, and 12 had reached Archerfield in Australia. The B-25s in Australia were used as
5200-707: The Normandy invasion, the RAF and France used Mitchells in support of the Allies in Europe. Several squadrons moved to forward airbases on the continent. The USAAF used the B-25 in combat in the Mediterranean Theater of Operations . The B-25B found fame as the bomber used in the 18 April 1942 Doolittle Raid , in which 15 B-25Bs led by Lieutenant Colonel Jimmy Doolittle attacked mainland Japan, four months after
5330-853: The Royal Dutch Naval Air Service , who had escaped to England after the German occupation of the Netherlands. Equipped with various British aircraft, No. 320 Squadron flew antisubmarine patrols, convoy escort missions, and performed air-sea rescue duties. They acquired the Mitchell II in September 1943, performing operations over Europe against gun emplacements, railway yards, bridges, troops, and other tactical targets. They moved to Belgium in October 1944, and transitioned to
North American B-25 Mitchell - Misplaced Pages Continue
5460-545: The Weber , Rinne , Bing and Schwabach tests. In case of infection or inflammation, blood or other body fluids may be submitted for laboratory analysis. MRI and CT scans can be useful to identify the pathology of many causes of hearing loss. Hearing loss is categorized by severity, type, and configuration. Furthermore, a hearing loss may exist in only one ear (unilateral) or in both ears (bilateral). Hearing loss can be temporary or permanent, sudden or progressive. The severity of
5590-644: The de Havilland Mosquito . In addition to No. 2 Group, the B-25 was used by various second-line RAF units in the UK and abroad. In the Far East, No. 3 PRU, which consisted of Nos. 681 and 684 Squadrons, flew the Mitchell (primarily Mk IIs) on photographic reconnaissance sorties. The Royal Canadian Air Force (RCAF) used the B-25 Mitchell for training during the war. Postwar use continued operations with most of
5720-400: The eardrum , causing it to vibrate. The vibrations are transferred by the 3 tiny ear bones of the middle ear to the fluid in the inner ear. The fluid moves hair cells ( stereocilia ), and their movement generates nerve impulses which are then taken to the brain by the cochlear nerve . The auditory nerve takes the impulses to the brainstem, which sends the impulses to the midbrain. Finally,
5850-459: The 162 Mitchells received. The first B-25s had been diverted to Canada from RAF orders. These included one Mitchell I, 42 Mitchell IIs, and 19 Mitchell IIIs. No 13 (P) Squadron was formed unofficially at RCAF Rockcliffe in May 1944 and used Mitchell IIs on high-altitude aerial photography sorties. No. 5 Operational Training Unit at Boundary Bay, British Columbia and Abbotsford, British Columbia, operated
5980-644: The AAFAC format, the Marine Mitchells had search radar in a retractable radome replacing the remotely operated ventral turret. Later D and J series had nose-mounted APS-3 radar; and later still, J and H series mounted radar in the starboard wingtip. The large quantities of B-25H and J series became known as PBJ-1H and PBJ-1J, respectively. These aircraft often operated along with earlier PBJ series in Marine squadrons. The PBJs were operated almost exclusively by
6110-645: The Aegean Sea, the B-25 conducted sea sweeps as part of the coastal air forces. In Italy, the B-25 was used in the ground attack role, concentrating on attacks against road and rail links in Italy, Austria, and the Balkans. The B-25 had a longer range than the Douglas A-20 Havoc and Douglas A-26 Invader , allowing it to reach further into occupied Europe. The five bombardment groups – 20 squadrons – of
6240-572: The B-25A and B-25B series entered USAAF service. The B-25B was operational in 1942. Combat requirements led to further developments. Before the year was over, NAA was producing the B-25C and B-25D series at different plants. Also in 1942, the manufacturer began design work on the cannon-armed B-25G series. The NA-100 of 1943 and 1944 was an interim armament development at the Kansas City complex known as
6370-707: The B-25D Mitchell in the training role together with B-24 Liberators for Heavy Conversion as part of the BCATP. The RCAF retained the Mitchell until October 1963. No 418 (Auxiliary) Squadron received its first Mitchell IIs in January 1947. It was followed by No 406 (auxiliary), which flew Mitchell IIs and IIIs from April 1947 to June 1958. No 418 operated a mix of IIs and IIIs until March 1958. No 12 Squadron of Air Transport Command also flew Mitchell IIIs along with other types from September 1956 to November 1960. In 1951,
6500-761: The B-25D2 and ordered as the NA-100. NAA built a total of 3,915 B-25Cs and Ds during World War II. Although the B-25 was designed to bomb from medium altitudes in level flight, it was frequently used in the Southwest Pacific theatre in treetop-level strafing and missions with parachute-retarded fragmentation bombs against Japanese airfields in New Guinea and the Philippines. These heavily armed Mitchells were field-modified at Townsville , Australia, under
6630-625: The B-25D2. Similar armament upgrades by U.S-based commercial modification centers involved about half of the B-25G series. Further development led to the B-25H, B-25J, and B-25J2. The gunship design concept dates to late 1942 and NAA sent a field technical representative to the SWPA. The factory-produced B-25G entered production during the NA-96 order followed by the redesigned B-25H gunship. The B-25J reverted to
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#17327799108966760-517: The B-25G. In this series, the transparent nose and bombardier/navigator position was changed for a shorter, hatched nose with two fixed .50 in (12.7 mm) machine guns and a manually loaded 75 mm (2.95 in) M4 cannon , one of the largest weapons fitted to an aircraft, similar to the British 57 mm gun -armed Mosquito Mk. XVIII and the autoloading German 75 mm long-barrel Bordkanone BK 7,5 heavy-caliber ordnance fitted to both
6890-408: The B-25H could "bring to bear 10 machine guns coming and four going, in addition to the 75 mm cannon, eight rockets , and 3,000 lb (1,360 kg) of bombs." The H had a modified cockpit with single flight controls operated by the pilot. The co-pilot's station and controls were removed and replaced by a smaller seat used by the navigator/cannoneer, The radio operator crew position was aft of
7020-519: The B-25J series. It optimized the mix of the interim NA-100 and the H series, having both the bombardier's station and fixed guns of the D and the forward turret and refined armament of the H series. NAA also produced a strafer nose-first shipped to air depots as kits, then introduced on the production line in alternating blocks with the bombardier nose. The solid metal "strafer" nose housed eight centerline Browning M2 .50 caliber machine guns. The remainder of
7150-677: The Cochrane Review was that further research could modify what is now regarding the effectiveness of the evaluated interventions. The Institute for Occupational Safety and Health of the German Social Accident Insurance has created a hearing impairment calculator based on the ISO 1999 model for studying threshold shift in relatively homogeneous groups of people, such as workers with the same type of job. The ISO 1999 model estimates how much hearing impairment in
7280-506: The Far East of Russia, and one Doolittle Raid aircraft landed there short of fuel after attacking Japan. This lone airworthy Doolittle Raid aircraft to reach the Soviet Union was lost in a hangar fire in the early 1950s while undergoing routine maintenance. In general, the B-25 was operated as a ground-support and tactical day bomber (as similar Douglas A-20 Havocs were used). It saw action in fights from Stalingrad (with B/C/D models) to
7410-821: The German surrender during May 1945 (with G/J types). The B-25s that remained in Soviet Air Force service after the war were assigned the NATO reporting name "Bank". Well over 100 B-25Cs and Ds were supplied to the Nationalist Chinese during the Second Sino-Japanese War . In addition, a total of 131 B-25Js were supplied to China under Lend-Lease. Medium bomber The term was used prior to and during World War II , based on available parameters of engine and aeronautical technology for bomber aircraft designs at that time. After
7540-516: The HPD (without individual selection, training and fit testing ) does not significantly reduce the risk of hearing loss. The use of antioxidants is being studied for the prevention of noise-induced hearing loss, particularly for scenarios in which noise exposure cannot be reduced, such as during military operations. Noise is widely recognized as an occupational hazard . In the United States,
7670-444: The J followed the overall configuration of the H series from the cockpit aft. It had the forward dorsal turret and other armament and airframe advancements. All J models included four .50 in (12.7 mm) light-barrel Browning AN/M2 guns in a pair of "fuselage packages", conformal gun pods each flanking the lower cockpit, each pod containing two Browning M2s . By 1945, however, combat squadrons removed these. The J series restored
7800-736: The Marine Corps PBJ-1s began in March 1944. The Marine PBJs flew from the Philippines, Saipan, Iwo Jima , and Okinawa during the last few months of the Pacific war. Their primary mission was the long-range interdiction of enemy shipping trying to run the blockade, which was strangling Japan. The weapon of choice during these missions was usually the five-inch HVAR rocket, eight of which could be carried. Some VMB-612 intruder PBJ-1D and J series planes flew without top turrets to save weight and increase range on night patrols, especially towards
7930-484: The Marine Corps as land-based bombers. The U.S. Marine Corps established Marine bomber squadrons (VMB), beginning with VMB-413, in March 1943 at MCAS Cherry Point , North Carolina. Eight VMB squadrons were flying PBJs by the end of 1943 as the initial Marine medium bombardment group. Four more squadrons were in the process of formation in late 1945, but had not yet deployed by the time the war ended. Operations of
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#17327799108968060-794: The Mitchell III in 1945. No. 320 Squadron was disbanded in August 1945. Following the war, B-25s were used by Dutch forces during the Indonesian National Revolution . The USSR received 862 B-25s (B, C, D, G, and J types) from the United States under Lend-Lease during World War II via the Alaska–Siberia ALSIB ferry route. A total of 870 B-25s were sent to the Soviets, meaning that 8 aircraft were lost during transportation. Other damaged B-25s arrived or crashed in
8190-583: The Mitchell on coastal patrols after the Pearl Harbor attack, prior to the AAFAC organization. Many of the two dozen or so antisubmarine squadrons flew the B-25C, D, and G series in the American Theater antisubmarine campaign, often in the distinctive, white sea-search camouflage. In anti-shipping operations, the USAAF had an urgent need for hard-hitting aircraft, and North American responded with
8320-718: The Mitchell served in fairly large numbers with the Air Force of the Dutch government-in-exile. They participated in combat in the East Indies , as well as on the European front. On 30 June 1941, the Netherlands Purchasing Commission, acting on behalf of the Dutch government-in-exile in London, signed a contract with North American Aviation for 162 B-25C aircraft. The bombers were to be delivered to
8450-593: The NA-62, which competed for the medium bomber contract. No YB-25 was available for prototype service tests. In September 1939, the Air Corps ordered the NA-62 into production as the B-25, along with the other new Air Corps medium bomber, the Martin B-26 Marauder "off the drawing board". Early into B-25 production, NAA incorporated a significant redesign to the wing dihedral . The first nine aircraft had
8580-874: The NAA strafer nose, the J2 subseries. In Burma, the B-25 was used to attack Japanese communication links, especially bridges in central Burma. It also helped supply the besieged troops at Imphal in 1944. The China Air Task Force, the Chinese American Composite Wing, the First Air Commando Group, the 341st Bomb Group, and eventually, the relocated 12th Bomb Group, all operated the B-25 in the China Burma India Theater . Many of these missions involved battle-field isolation, interdiction, and close air support . Later in
8710-579: The Navy and the USAAF exchanging the Boeing Renton plant for the Kansas plant for B-29 Superfortress production. The Boeing XPBB Sea Ranger flying boat, competing for B-29 engines, was cancelled in exchange for part of the Kansas City Mitchell production. Other terms included the interservice transfer of 50 B-25Cs and 152 B-25Ds to the Navy. The bombers carried Navy bureau numbers (BuNos), beginning with BuNo 34998. The first PBJ-1 arrived in February 1943, and nearly all reached Marine Corps squadrons, beginning with Marine Bombing Squadron 413 (VMB-413). Following
8840-402: The Niceville-Valparaiso Chamber of Commerce. Four of the original Tokyo Raiders were present for the ceremony, Colonel (later Major General) David Jones , Colonel Jack Simms, Lieutenant Colonel Joseph Manske, and retired Master Sergeant Edwin W. Horton. It was donated back to the Air Force Armament Museum c. 1974 and marked as Doolittle's 40-2344 . The U.S. Navy designation for the Mitchell
8970-412: The Ninth and Twelfth Air Forces that used the B-25 in the Mediterranean Theater of Operations were the only U.S. units to employ the B-25 in Europe. The RAF received nearly 900 Mitchells, using them to replace Douglas Bostons , Lockheed Venturas , and Vickers Wellington bombers. The Mitchell entered active RAF service on 22 January 1943. At first, it was used to bomb targets in occupied Europe. After
9100-441: The Pacific . The Mitchell fought from the Northern Pacific to the South Pacific and the Far East. These areas included the campaigns in the Aleutian Islands , Papua New Guinea , the Solomon Islands, New Britain , China, Burma and the island hopping campaign in the Central Pacific, as well as in the Doolittle Raid . The aircraft's potential as a ground- attack aircraft emerged during the Pacific war. The jungle environment reduced
9230-492: The RAF. The RAF tested the cannon-armed G series but did not adopt the series nor the follow-on H series. By the end of 1942, the RAF had taken delivery of 93 Mitchells, marks I and II. Some served with squadrons of No. 2 Group RAF , the RAF's tactical medium-bomber force, including No. 139 Wing RAF at RAF Dunsfold . The first RAF operation with the Mitchell II took place on 22 January 1943, when six aircraft from No. 180 Squadron RAF attacked oil installations at Ghent . After
9360-523: The RCAF received an additional 75 B-25Js from USAF stocks to make up for attrition and to equip various second-line units. The Australians received Mitchells by the spring of 1944. The joint Australian-Dutch No. 18 (Netherlands East Indies) Squadron RAAF had more than enough Mitchells for one squadron, so the surplus went to re-equip the RAAF's No. 2 Squadron , replacing their Beauforts . During World War II,
9490-547: The Southwest Pacific Theater during 1944 to 1945. The USAAF played a significant role in pushing the Japanese back to their home islands. The type operated with great effect in the Central Pacific , Alaska , North Africa , Mediterranean , and China-Burma-India theaters. The USAAF Antisubmarine Command made great use of the B-25 in 1942 and 1943. Some of the earliest B-25 bomb groups also flew
9620-484: The US Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) introduces the issue, provides examples of ototoxic chemicals, lists the industries and occupations at risk and provides prevention information. There can be damage either to the ear, whether the external or middle ear, to the cochlea, or to the brain centers that process
9750-587: The adaptations that allow them to live independently. Prelingual deafness is profound hearing loss that is sustained before the acquisition of language, which can occur due to a congenital condition or through hearing loss before birth or in early infancy. Prelingual deafness impairs an individual's ability to acquire a spoken language in children, but deaf children can acquire spoken language through support from cochlear implants (sometimes combined with hearing aids). Non-signing (hearing) parents of deaf babies (90–95% of cases) usually go with oral approach without
9880-422: The aircraft could snap out of control. The tricycle landing gear made for excellent visibility while taxiing. The only significant complaint about the B-25 was its extremely noisy engines; as a result, many pilots eventually suffered from some degree of hearing loss . The high noise level was due to design and space restrictions in the engine cowlings, which resulted in the exhaust "stacks" protruding directly from
10010-400: The aircraft did not enter production. The B-25 was a safe and forgiving aircraft to fly. With one engine out, 60° banking turns into the dead engine were possible, and control could be easily maintained down to 145 mph (230 km/h). The pilot had to remember to maintain engine-out directional control at low speeds after takeoff with rudder; if this maneuver were attempted with ailerons,
10140-530: The armament was as in the H-5. NAA also supplied kits to mount eight underwing 5 inch High Velocity Airborne Rockets just outside the propeller arcs. These were mounted on zero-length launch rails, four per wing. The final, and most numerous, series of the Mitchell, the B-25J , looked less like earlier series apart from the well-glazed bombardier's nose of nearly identical appearance to the earliest B-25 subtypes. Instead,
10270-543: The association between hearing loss and cognitive decline is mediated through various psychosocial factors, such as decrease in social contact and increase in social isolation . Findings on the association between hearing loss and dementia have significant public health implication, since about 9% of dementia cases are associated with hearing loss. Falls have important health implications, especially for an aging population where they can lead to significant morbidity and mortality. Elderly people are particularly vulnerable to
10400-406: The aural information conveyed by the ears. Damage to the middle ear may include fracture and discontinuity of the ossicular chain. Damage to the inner ear (cochlea) may be caused by temporal bone fracture . People who sustain head injury are especially vulnerable to hearing loss or tinnitus, either temporary or permanent. Sound waves reach the outer ear and are conducted down the ear canal to
10530-452: The bomb bay with access to the waist guns. Factory production totals were 405 B-25Gs and 1,000 B-25Hs, with 248 of the latter being used by the Navy as PBJ-1Hs. Elimination of the co-pilot saved weight, and moving the dorsal turret forward partially counterbalanced the waist guns and the manned rear turret. Following the two-gunship series, NAA again produced the medium bomber configuration with
10660-631: The bomber role, but it, too, could be outfitted as a strafer. NAA manufactured the greatest number of aircraft in World War II, the first time a company had produced trainers, bombers, and fighters simultaneously (the AT-6/SNJ Texan/Harvard , B-25 Mitchell, and the P-51 Mustang ). It produced B-25s at both its Inglewood main plant and an additional 6,608 aircraft at its Kansas City, Kansas , plant at Fairfax Airport . After
10790-547: The child. Hearing loss is diagnosed when hearing testing finds that a person is unable to hear 25 decibels in at least one ear. Testing for poor hearing is recommended for all newborns. Hearing loss can be categorized as mild (25 to 40 dB ), moderate (41 to 55 dB), moderate-severe (56 to 70 dB), severe (71 to 90 dB), or profound (greater than 90 dB). There are three main types of hearing loss: conductive hearing loss , sensorineural hearing loss , and mixed hearing loss. About half of hearing loss globally
10920-459: The co-pilot's seat and dual flight controls. The factory-made kits available to the Air Depot system to create the strafer-nose B-25J-2. This configuration carried a total of 18 .50 in (12.7 mm) light-barrel AN/M2 Browning M2 machine guns: eight in the nose, four in the flank-mount conformal gun pod packages, two in the dorsal turret, one each in the pair of waist positions, and a pair in
11050-449: The consequences of injuries caused by falls, since older individuals typically have greater bone fragility and poorer protective reflexes. Fall-related injury can also lead to burdens on the financial and health care systems. In literature, age-related hearing loss is found to be significantly associated with incident falls. There is also a potential dose-response relationship between hearing loss and falls—greater severity of hearing loss
11180-416: The cowling ring and partly covered by a small triangular fairing. This arrangement directed exhaust and noise directly at the pilot and crew compartments. The Mitchell was exceptionally sturdy and could withstand tremendous punishment. One B-25C of the 321st Bomb Group was nicknamed "Patches" because its crew chief painted all the aircraft's flak hole patches with bright yellow zinc chromate primer . By
11310-471: The deafness in an individual. Fetal alcohol spectrum disorders are reported to cause hearing loss in up to 64% of infants born to alcoholic mothers, from the ototoxic effect on the developing fetus plus malnutrition during pregnancy from the excess alcohol intake. Premature birth can be associated with sensorineural hearing loss because of an increased risk of hypoxia , hyperbilirubinaemia , ototoxic medication and infection as well as noise exposure in
11440-601: The detrimental effects of the untreated condition on quality of life. For the same reason, the US Office of Disease Prevention and Health Promotion included as one of Healthy People 2020 objectives: to increase the proportion of persons who have had a hearing examination. Management depends on the specific cause if known as well as the extent, type and configuration of the hearing loss. Sudden hearing loss due to an underlying nerve problem may be treated with corticosteroids . Most hearing loss, that result from age and noise,
11570-618: The development of the gunship version. NAA Inglewood produced 1000. The H had even more firepower. Most replaced the M4 gun with the lighter T13E1 , designed specifically for the aircraft, but 20-odd H-1 block aircraft completed by the Republic Aviation modification center at Evansville had the M4 and two-machine-gun nose armament. The 75 mm (2.95 in) gun fired at a muzzle velocity of 2,362 ft/s (720 m/s ). Due to its slow rate of fire (about four rounds could be fired in
11700-568: The direction of Major Paul I. "Pappy" Gunn and North American technical representative Jack Fox. These "commerce destroyers" were also used on strafing and skip bombing missions against Japanese shipping trying to resupply their armies. Under the leadership of Lieutenant General George C. Kenney , Mitchells of the Far East Air Forces and its existing components, the Fifth and Thirteenth Air Forces , devastated Japanese targets in
11830-470: The end of the war when air superiority had been achieved. During the war, the Navy tested the cannon-armed G series and conducted carrier trials with an H equipped with arresting gear. After World War II, some PBJs stationed at the Navy's rocket laboratory in Inyokern, California , site of the present-day Naval Air Weapons Station China Lake , tested air-to-ground rockets and arrangements. One arrangement
11960-529: The end of the war, this aircraft had completed over 300 missions, had been belly-landed six times, and had over 400 patched holes. The airframe of "Patches" was so distorted from battle damage that straight-and-level flight required 8° of left aileron trim and 6° of right rudder, causing the aircraft to "crab" sideways across the sky. Most B-25s in American service were used in the war against Japan in Asia and
12090-479: The failure to activate electronic homing aids at the recovery bases. Only one B-25 bomber landed intact, in Vladivostok , where its five-man crew was interned and the aircraft confiscated. Of the 80 aircrew members, 69 survived their historic mission and eventually made it back to American lines. Following additional modifications, including the addition of a Plexiglas dome for navigational sightings to replace
12220-408: The first three years of life are believed to be the most important for language development. Universal neonatal hearing screenings have now been widely implemented across the U.S., with rates of newborn screening increasing from less than 3% in the early 1990s to 98% in 2009. Newborns whose screening reveals a high index of suspicion of hearing loss are referred for additional diagnostic testing with
12350-717: The goal of providing early intervention and access to language. The American Academy of Pediatrics advises that children should have their hearing tested several times throughout their schooling: While the American College of Physicians indicated that there is not enough evidence to determine the utility of screening in adults over 50 years old who do not have any symptoms, the American Language, Speech Pathology and Hearing Association recommends that adults should be screened at least every decade through age 50 and at three-year intervals thereafter, to minimize
12480-484: The hearing loss degree. There are several hypotheses including cognitive resources being redistributed to hearing and social isolation from hearing loss having a negative effect. According to preliminary data, hearing aid usage can slow down the decline in cognitive functions . Hearing loss is responsible for causing thalamocortical dysrthymia in the brain which is a cause for several neurological disorders including tinnitus and visual snow syndrome . Hearing loss
12610-627: The invasion of Europe (by which point 2 Group was part of Second Tactical Air Force ), all four Mitchell squadrons moved to bases in France and Belgium (Melsbroek) to support Allied ground forces. The British Mitchell squadrons were joined by No. 342 (Lorraine) Squadron of the French Air Force in April 1945. As part of its move from Bomber Command, No 305 (Polish) Squadron flew Mitchell IIs from September to December 1943 before converting to
12740-1555: The neonatal units. Also, hearing loss in premature babies is often discovered far later than a similar hearing loss would be in a full-term baby because normally babies are given a hearing test within 48 hours of birth, but doctors must wait until the premature baby is medically stable before testing hearing, which can be months after birth. The risk of hearing loss is greatest for those weighing less than 1500 g at birth. Disorders responsible for hearing loss include auditory neuropathy , Down syndrome , Charcot–Marie–Tooth disease variant 1E, autoimmune disease , multiple sclerosis , meningitis , cholesteatoma , otosclerosis , perilymph fistula , Ménière's disease , recurring ear infections, strokes, superior semicircular canal dehiscence , Pierre Robin , Treacher-Collins , Usher Syndrome , Pendred Syndrome , and Turner syndrome, syphilis , vestibular schwannoma , and viral infections such as measles , mumps , congenital rubella (also called German measles) syndrome, several varieties of herpes viruses , HIV/AIDS , and West Nile virus . Some medications may reversibly or irreversibly affect hearing. These medications are considered ototoxic . This includes loop diuretics such as furosemide and bumetanide, non-steroidal anti-inflammatory drugs (NSAIDs) both over-the-counter (aspirin, ibuprofen, naproxen) as well as prescription (celecoxib, diclofenac, etc.), paracetamol, quinine , and macrolide antibiotics . Others may cause permanent hearing loss. The most important group
12870-419: The nerves from the ear to the brain. Identification of a hearing loss is usually conducted by a general practitioner medical doctor , otolaryngologist , certified and licensed audiologist , school or industrial audiometrist , or other audiometric technician. Diagnosis of the cause of a hearing loss is carried out by a specialist physician (audiovestibular physician) or otorhinolaryngologist . Hearing loss
13000-506: The nose; four in a pair of under-cockpit conformal flank-mount gun pod packages (two guns per side); two more in the manned dorsal turret, relocated forward to a position just behind the cockpit (which became standard for the J-model); one each in a pair of new waist positions, introduced simultaneously with the forward-relocated dorsal turret; and lastly, a pair of guns in a new tail-gunner's position. Company promotional material bragged that
13130-400: The nucleus of a new squadron, No. 18. This squadron was staffed jointly by Australian and Dutch aircrews plus a smattering of aircrews from other nations and operated under Royal Australian Air Force command for the remainder of the war. The B-25s of No. 18 Squadron were painted with the Dutch national insignia (at that time a rectangular Netherlands flag) and carried NEIAF serials. Discounting
13260-436: The overhead window for the navigator, and heavier nose armament, de-icing and anti-icing equipment, the B-25C entered USAAF operations. Through block 20, the B-25C and B-25D differed only in the location of manufacture: C series at Inglewood, California , and D series at Kansas City, Kansas . After block 20, some NA-96s began the transition to the G series, while some NA-87s acquired interim modifications eventually produced as
13390-525: The population globally. The majority of hearing loss is not due to age, but due to noise exposure. Various governmental, industry and standards organizations set noise standards. Many people are unaware of the presence of environmental sound at damaging levels, or of the level at which sound becomes harmful. Common sources of damaging noise levels include car stereos, children's toys, motor vehicles, crowds, lawn and maintenance equipment, power tools, gun use, musical instruments, and even hair dryers. Noise damage
13520-448: The potential of age-appropriate development of language due to early exposure to a sign language by sign-competent parents, thus they have the potential to meet language milestones, in sign language in lieu of spoken language. Hearing loss has multiple causes, including ageing, genetics, perinatal problems and acquired causes like noise and disease. For some kinds of hearing loss the cause may be classified as of unknown cause . There
13650-400: The presence of a schwannoma or other tumor. People with unilateral hearing loss or single-sided deafness (SSD) have difficulty in hearing conversation on their impaired side, localizing sound, and understanding speech in the presence of background noise. One reason for the hearing problems these patients often experience is due to the head shadow effect . Idiopathic sudden hearing loss
13780-446: The remainder of the war. The raiders took off from the carrier USS Hornet and bombed Tokyo and four other Japanese cities. Fifteen of the bombers subsequently crash-landed en route to recovery fields in eastern China. The losses resulted from the task force being spotted by a Japanese vessel, which forced the bombers to take off 170 mi (270 km) early, fuel exhaustion, stormy nighttime conditions with zero visibility, and
13910-501: The roles performed by mediums. After the war, use of the term generally vanished; some of this was due to mass demobilization of the participant air forces' existing equipment, and the fact that several of the most-produced medium bomber types were now technologically obsolescent. Although a number of later aircraft were designed in this performance and load-carrying range, they were henceforth referred to as tactical bombers or strike aircraft instead. Examples of post-war mediums include
14040-405: The signal goes to the auditory cortex of the temporal lobe to be interpreted as sound. Hearing loss is most commonly caused by long-term exposure to loud noises, from recreation or from work, that damage the hair cells, which do not grow back on their own. Older people may lose their hearing from long exposure to noise, changes in the inner ear, changes in the middle ear, or from changes along
14170-465: The so-called "Hayes modification" and as a result, surviving B-25s often have exhaust systems with a semi collector ring that splits emissions into two different systems. The upper seven cylinders are collected by a ring, while the other cylinders remain directed to individual ports. TB-25J-25-NC Mitchell, 44-30854 , the last B-25 in the USAF inventory, assigned at March AFB , California, as of March 1960,
14300-501: The softest sound an average unimpaired human ear can hear; some people can hear down to −5 or even −10 dB. Sound is generally uncomfortably loud above 90 dB and 115 dB represents the threshold of pain . The ear does not hear all frequencies equally well: hearing sensitivity peaks around 3,000 Hz. There are many qualities of human hearing besides frequency range and intensity that cannot easily be measured quantitatively. However, for many practical purposes, normal hearing
14430-512: The support of sign language, as these families lack previous experience with sign language and cannot competently provide it to their children without learning it themselves. This may in some cases (late implantation or not sufficient benefit from cochlear implants) bring the risk of language deprivation for the deaf baby because the deaf baby would not have a sign language if the child is unable to acquire spoken language successfully. The 5–10% of cases of deaf babies born into signing families have
14560-411: The suspected cause of the sudden hearing loss. Treatment approaches may include corticosteroid medications, rheological drugs, vasodilators, anesthetics, and other medications chosen based on the suspected underlying pathology that caused the sudden hearing loss. The evidence supporting most treatment options for idiopathic sudden hearing loss is very weak and adverse effects of these different medications
14690-530: The tail – with 14 of the guns either aimed directly forward or aimed to fire directly forward for strafing missions. Some aircraft had eight 5-inch (130 mm) high-velocity aircraft rockets . NAA introduced the J-2 into production in alternating blocks at the J-22. Total J series production was 4,318. In 1947, legislation created an independent United States Air Force and by that time, the B-25 inventory numbered only
14820-553: The ten "temporary" B-25s delivered to 18 Squadron in early 1942, a total of 150 Mitchells were taken on strength by the NEIAF, 19 in 1942, 16 in 1943, 87 in 1944, and 28 in 1945. They flew bombing raids against Japanese targets in the East Indies. In 1944, the more capable B-25J Mitchells replaced most of the earlier C and D models. In June 1940, No. 320 (Netherlands) Squadron RAF had been formed from personnel formerly serving with
14950-568: The time. Some of these bombers, such as the Heinkel He 111 , Junkers Ju 86 , Savoia-Marchetti SM.79 , Douglas B-18 , and Armstrong Whitworth Whitley were developed from or in conjunction with existing airliners or transport aircraft. The World War II-era medium bomber was generally considered to be any level bomber design that delivered about 4,000 pounds (1,800 kg) of ordnance over ranges of about 1,500 to 2,000 mi (2,400 to 3,200 km). Typical heavy bombers were those with
15080-550: The underlying causal mechanism for age-related hearing loss and cognitive decline. One hypothesis is that this association can be explained by common etiology or shared neurobiological pathology with decline in other physiological system. Another possible cognitive mechanism emphasize on individual's cognitive load . As people developing hearing loss in the process of aging, the cognitive load demanded by auditory perception increases, which may lead to change in brain structure and eventually to dementia. One other hypothesis suggests that
15210-420: The use of certain medications harmful to the ear. While everyone loses hearing with age, the amount and type of hearing loss is variable. Noise-induced hearing loss (NIHL), also known as acoustic trauma , typically manifests as elevated hearing thresholds (i.e. less sensitivity or muting). Noise exposure is the cause of approximately half of all cases of hearing loss, causing some degree of problems in 5% of
15340-522: The usefulness of medium-level bombing, and made low-level attack the best tactic. Using similar mast height level tactics and skip bombing , the B-25 proved itself to be a capable anti-shipping weapon and sank many enemy sea vessels. An ever-increasing number of forward firing guns made the B-25 a formidable strafing aircraft for island warfare. The strafer models were the B-25C1/D1, the B-25J1 and with
15470-467: The variability in study design and protocols, the majority of these studies have found consistent association between age-related hearing loss and cognitive decline, cognitive impairment, and dementia. The association between age-related hearing loss and Alzheimer's disease was found to be nonsignificant, and this finding supports the hypothesis that hearing loss is associated with dementia independent of Alzheimer pathology. There are several hypotheses about
15600-531: The war, as the USAAF acquired bases in other parts of the Pacific, the Mitchell could strike targets in Indochina , Formosa , and Kyushu , increasing the usefulness of the B-25. It was also used in some of the shortest raids of the Pacific War, striking from Saipan against Guam and Tinian . The 41st Bomb Group used it against Japanese-occupied islands that had been bypassed by the main campaign, such as
15730-452: The war, medium bombers were replaced in world air forces by more advanced and capable aircraft. In the early 1930s many air forces were looking to modernize their existing bomber aircraft fleets, which frequently consisted of older biplanes . The new designs were typically twin-engined monoplanes , often of all-metal construction, and optimized for high enough performance and speed to help evade rapidly evolving fighter aircraft designs of
15860-598: The war, the USAF placed a contract for the TB-25L trainer in 1952. This was a modification program by Hayes of Birmingham, Alabama . Its primary role was reciprocating engine pilot training. A development of the B-25 was the North American XB-28 Dragon , designed as a high-altitude bomber. Two prototypes were built with the second prototype, the XB-28A, evaluated as a photo-reconnaissance platform, but
15990-461: The worker and type of employment. Some hearing protectors universally block out all noise, and some allow for certain noises to be heard. Workers are more likely to wear hearing protector devices when they are properly fitted. Often interventions to prevent noise-induced hearing loss have many components. A 2017 Cochrane review found that stricter legislation might reduce noise levels. Providing workers with information on their sound exposure levels
16120-766: The workplace. For example, the Safe-in-Sound Award was created to recognize organizations that can demonstrate results of successful noise control and other interventions. Additionally, the Buy Quiet program was created to encourage employers to purchase quieter machinery and tools. By purchasing less noisy power tools like those found on the NIOSH Power Tools Database and limiting exposure to ototoxic chemicals, great strides can be made in preventing hearing loss. Companies can also provide personal hearing protector devices tailored to both
16250-595: Was a twin-barrel nose that could fire 10 spin-stabilized five-inch rockets in one salvo. The Royal Air Force (RAF) was an early customer for the B-25 via Lend-Lease . The first Mitchells were given the service name Mitchell I by the RAF and were delivered in August 1941, to No. 111 Operational Training Unit based in the Bahamas . These bombers were used exclusively for training and familiarization and never became operational. The B-25Cs and Ds were designated Mitchell II. Altogether, 167 B-25Cs and 371 B-25Ds were delivered to
16380-544: Was flown to Eglin AFB , Florida, from Turner Air Force Base , Georgia, on 21 May 1960, the last flight by a USAF B-25. It was presented by Brigadier General A. J. Russell, Commander of SAC 's 822d Air Division at Turner AFB, to the Air Proving Ground Center Commander, Brigadier General Robert H. Warren. He in turn presented the bomber to Valparaiso, Florida , Mayor Randall Roberts on behalf of
16510-612: Was not shown to decrease exposure to noise. Ear protection, if used correctly, can reduce noise to safer levels, but often, providing them is not sufficient to prevent hearing loss. Engineering noise out and other solutions such as proper maintenance of equipment can lead to noise reduction, but further field studies on resulting noise exposures following such interventions are needed. Other possible solutions include improved enforcement of existing legislation and better implementation of well-designed prevention programmes, which have not yet been proven conclusively to be effective. The conclusion of
16640-588: Was purely semantic and bureaucratic, however as both the B-47 and B-52 strategic bombers were much larger and had far greater performance and load-carrying ability than any of the World War II-era heavy or medium bombers. Similarly, the Royal Air Force referred at times to its V bomber force as medium bombers, but this was in terms of range rather than load-carrying capacity. Although the term
16770-467: Was the PBJ-1 and apart from increased use of radar, it was configured like its Army Air Forces counterparts. Under the pre-1962 USN/USMC/USCG aircraft designation system, PBJ-1 stood for Patrol (P) Bomber (B) built by North American Aviation (J), first variant (-1) under the existing American naval aircraft designation system of the era . The PBJ had its origin in an inter-service agreement of mid-1942 between
16900-806: Was the most-produced American medium bomber and the third most-produced American bomber overall . These included several limited models such as the F-10 reconnaissance aircraft , the AT-24 crew trainers, and the United States Marine Corps ' PBJ-1 patrol bomber . In March 1939, the US Army Air Corps issued a specification for a medium bomber that was capable of carrying a payload of 2,400 lb (1,100 kg) over 1,200 miles (1,900 km) at 300 mph (480 km/h). North American Aviation (NAA) used its NA-40B design to develop
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