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113-497: Ultrasound is sound with frequencies greater than 20 kilohertz . This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound. Ultrasonic devices operate with frequencies from 20 kHz up to several gigahertz. Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasound imaging or sonography

226-429: A root mean square (RMS) value. For example, 1 Pa RMS sound pressure (94 dBSPL) in atmospheric air implies that the actual pressure in the sound wave oscillates between (1 atm − 2 {\displaystyle -{\sqrt {2}}} Pa) and (1 atm + 2 {\displaystyle +{\sqrt {2}}} Pa), that is between 101323.6 and 101326.4 Pa. As the human ear can detect sounds with

339-413: A transducer that generates vibrations. The microphone of the hearing aid picks up sound signals from the environment. The signal is then optimized and transmitted to the transducer, which generates vibrations. Depending on the specific bone conduction hearing aid system, the vibrations are either sent directly through the skull bone, or through the skin towards the inner ear. Finally, the inner ear picks up

452-438: A 3 GHz sound wave could produce resolution comparable to an optical image, was recognized by Sergei Sokolov in 1939. Such frequencies were not possible at the time, and what technology did exist produced relatively low-contrast images with poor sensitivity. Ultrasonic imaging uses frequencies of 2 megahertz and higher; the shorter wavelength allows resolution of small internal details in structures and tissues. The power density

565-406: A bat, some insects will make evasive manoeuvres to escape being caught. Ultrasonic frequencies trigger a reflex action in the noctuid moth that causes it to drop slightly in its flight to evade attack. Tiger moths also emit clicks which may disturb bats' echolocation, and in other cases may advertise the fact that they are poisonous by emitting sound. Dogs and cats' hearing range extends into

678-402: A complication rate of up to 84%. In another study a meta-analysis of complications with osseointegrated hearing aids showed that revision surgery is required in up to 34.5% of cases. Transcutaneous devices were later designed to avoid or reduce recurring skin complications. An active bone conduction device is one where the implant generates the vibrations that directly stimulate the bone. With

791-516: A cylindrical, mica condenser by a high-frequency Poulsen arc at approximately 100 kHz and thus to generate an ultrasound beam for detecting submerged objects. The idea of locating underwater obstacles had been suggested prior by L. F. Richardson, following the Titanic disaster. Richardson had proposed to position a high-frequency hydraulic whistle at the focus of a mirror and use the beam for locating submerged navigational hazards. A prototype

904-436: A functioning cochlea but problems with the outer or inner ear that prevent sound vibrations from reaching the cochlea. This can be caused by conditions such as atresia , microtia , Goldenhar syndrome or Treacher Collins . Bone conduction is also a good option for someone who cannot use traditional air conduction hearing aids. Bone conduction devices are also used to help people with single-sided deafness , who have

1017-663: A given area as modified by the environment and understood by people, in context of the surrounding environment. There are, historically, six experimentally separable ways in which sound waves are analysed. They are: pitch , duration , loudness , timbre , sonic texture and spatial location . Some of these terms have a standardised definition (for instance in the ANSI Acoustical Terminology ANSI/ASA S1.1-2013 ). More recent approaches have also considered temporal envelope and temporal fine structure as perceptually relevant analyses. Pitch

1130-447: A humidifier's reservoir fall under the heading of "Humidifier Fever". Ultrasonic humidifiers are frequently used in aeroponics , where they are generally referred to as foggers . Sound In physics , sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology , sound is the reception of such waves and their perception by

1243-426: A large grain size that produces a high level of background noise in measurements. Ultrasonic thickness measurement is one technique used to monitor quality of welds. A common use of ultrasound is in underwater range finding ; this use is also called sonar . An ultrasonic pulse is generated in a particular direction. If there is an object in the path of this pulse, part or all of the pulse will be reflected back to

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1356-405: A medium such as air, water and solids as longitudinal waves and also as a transverse wave in solids . The sound waves are generated by a sound source, such as the vibrating diaphragm of a stereo speaker. The sound source creates vibrations in the surrounding medium. As the source continues to vibrate the medium, the vibrations propagate away from the source at the speed of sound , thus forming

1469-411: A non-functioning inner ear on one side. In this situation, the device picks up sounds on the non-functioning side and sends them as vibrations through the bone to the functioning cochlea on the other side. There are many different types of bone conduction hearing aids but most of them work on the same principle and comprise necessary components like microphones , signal processing , energy supply and

1582-488: A particular pitch is determined by pre-conscious examination of vibrations, including their frequencies and the balance between them. Specific attention is given to recognising potential harmonics. Every sound is placed on a pitch continuum from low to high. For example: white noise (random noise spread evenly across all frequencies) sounds higher in pitch than pink noise (random noise spread evenly across octaves) as white noise has more high frequency content. Duration

1695-531: A passive bone conduction device, the vibrations are generated by the audio processor before being passed through the skin or an abutment to reach the implant and the bone. The main active bone conduction devices available are the BONEBRIDGE from MED-EL and the Osia from Cochlear. Both are active transcutaneous devices. The external audio processor picks up sound vibrations and transmits them electronically through

1808-417: A pulsed-ultrasonic technology is that the transmit signal consists of short bursts of ultrasonic energy. After each burst, the electronics looks for a return signal within a small window of time corresponding to the time it takes for the energy to pass through the vessel. Only a signal received during this window will qualify for additional signal processing. A popular consumer application of ultrasonic ranging

1921-420: A recording of one's own voice frequently sounds higher than one expects (see voice confrontation ). Musicians may use bone conduction using a tuning fork while tuning stringed instruments. After the fork starts vibrating, placing it in the mouth with the stem between the back teeth ensures that one continues to hear the note via bone conduction, and both hands are free to do the tuning. Ludwig van Beethoven

2034-434: A specialized communication product is a bone conduction speaker that is used by scuba divers . The device is a rubber over-moulded, piezoelectric flexing disc that is approximately 40 millimetres (1.6 in) across and 6 millimetres (0.24 in) thick. A connecting cable is molded into the disc, resulting in a tough, waterproof assembly. In use, the speaker is strapped against one of the dome-shaped bone protrusions behind

2147-449: A substantial reduction in the reaction time, like in the transesterification of oil into biodiesel . Substantial ultrasonic intensity and high ultrasonic vibration amplitudes are required for many processing applications, such as nano-crystallization, nano-emulsification, deagglomeration, extraction, cell disruption, as well as many others. Commonly, a process is first tested on a laboratory scale to prove feasibility and establish some of

2260-654: A substantial time commitment for continuous data collection and operator training. Nevertheless, this technology has proven useful in managing and running a cattle breeding operation. High-power applications of ultrasound often use frequencies between 20 kHz and a few hundred kHz. Intensities can be very high; above 10 watts per square centimeter, cavitation can be inducted in liquid media, and some applications use up to 1000 watts per square centimeter. Such high intensities can induce chemical changes or produce significant effects by direct mechanical action, and can inactivate harmful microorganisms. Ultrasound has been used since

2373-469: A very fine spray), is a popular type of humidifier. It works by vibrating a metal plate at ultrasonic frequencies to nebulize (sometimes incorrectly called "atomize") the water. Because the water is not heated for evaporation, it produces a cool mist. The ultrasonic pressure waves nebulize not only the water but also materials in the water including calcium, other minerals, viruses, fungi, bacteria, and other impurities. Illness caused by impurities that reside in

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2486-466: A wide range of amplitudes, sound pressure is often measured as a level on a logarithmic decibel scale. The sound pressure level (SPL) or L p is defined as Since the human ear does not have a flat spectral response , sound pressures are often frequency weighted so that the measured level matches perceived levels more closely. The International Electrotechnical Commission (IEC) has defined several weighting schemes. A-weighting attempts to match

2599-413: Is a Real-Time Locating System (RTLS) or Indoor Positioning System (IPS) technology used to automatically track and identify the location of objects in real time using simple, inexpensive nodes (badges/tags) attached to or embedded in objects and devices, which then transmit an ultrasound signal to communicate their location to microphone sensors. The potential for ultrasonic imaging of objects, in which

2712-607: Is also increasingly being used in trauma and first aid cases, with emergency ultrasound being used by some EMT response teams. Furthermore, ultrasound is used in remote diagnosis cases where teleconsultation is required, such as scientific experiments in space or mobile sports team diagnosis. According to RadiologyInfo, ultrasounds are useful in the detection of pelvic abnormalities and can involve techniques known as abdominal (transabdominal) ultrasound, vaginal (transvaginal or endovaginal) ultrasound in women, and also rectal (transrectal) ultrasound in men. Diagnostic ultrasound

2825-488: Is also known as the Newton–Laplace equation. In this equation, K is the elastic bulk modulus, c is the velocity of sound, and ρ {\displaystyle \rho } is the density. Thus, the speed of sound is proportional to the square root of the ratio of the bulk modulus of the medium to its density. Those physical properties and the speed of sound change with ambient conditions. For example,

2938-446: Is also used to visualize fetuses during routine and emergency prenatal care . Such diagnostic applications used during pregnancy are referred to as obstetric sonography . As currently applied in the medical field, properly performed ultrasound poses no known risks to the patient. Sonography does not use ionizing radiation , and the power levels used for imaging are too low to cause adverse heating or pressure effects in tissue. Although

3051-564: Is an ultrasound-based diagnostic medical imaging technique used to visualize muscles, tendons, and many internal organs to capture their size, structure and any pathological lesions with real time tomographic images. Ultrasound has been used by radiologists and sonographers to image the human body for at least 50 years and has become a widely used diagnostic tool. The technology is relatively inexpensive and portable, especially when compared with other techniques, such as magnetic resonance imaging (MRI) and computed tomography (CT). Ultrasound

3164-399: Is an undesirable component that obscures a wanted signal. However, in sound perception it can often be used to identify the source of a sound and is an important component of timbre perception (see below). Soundscape is the component of the acoustic environment that can be perceived by humans. The acoustic environment is the combination of all sounds (whether audible to humans or not) within

3277-493: Is applied. These frequencies range between 25 and 55 kHz, with the displacement amplitude of the resonant body of between 22 and 50 μm (0.00087 and 0.0020 in). UIT devices rely on magnetostrictive transducers. Ultrasonication offers great potential in the processing of liquids and slurries, by improving the mixing and chemical reactions in various applications and industries. Ultrasonication generates alternating low-pressure and high-pressure waves in liquids, leading to

3390-420: Is called "direct scalability". It is important to point out that increasing the power of the ultrasonic processor alone does not result in direct scalability, since it may be (and frequently is) accompanied by a reduction in the ultrasonic amplitude and cavitation intensity. During direct scale-up, all processing conditions must be maintained, while the power rating of the equipment is increased in order to enable

3503-478: Is characterized by) its unique sounds. Many species, such as frogs, birds, marine and terrestrial mammals , have also developed special organs to produce sound. In some species, these produce song and speech . Furthermore, humans have developed culture and technology (such as music, telephone and radio) that allows them to generate, record, transmit, and broadcast sound. Noise is a term often used to refer to an unwanted sound. In science and engineering, noise

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3616-424: Is commonly used for diagnostics and treatment. Infrasound is sound waves with frequencies lower than 20 Hz. Although sounds of such low frequency are too low for humans to hear as a pitch, these sound are heard as discrete pulses (like the 'popping' sound of an idling motorcycle). Whales, elephants and other animals can detect infrasound and use it to communicate. It can be used to detect volcanic eruptions and

3729-445: Is defined as "(a) Oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation. (b) Auditory sensation evoked by the oscillation described in (a)." Sound can be viewed as a wave motion in air or other elastic media. In this case, sound is a stimulus. Sound can also be viewed as an excitation of

3842-439: Is fed directly into the human skull and reaches the cochlea through bone conduction , without passing through the middle ear. Children can hear some high-pitched sounds that older adults cannot hear, because in humans the upper limit pitch of hearing tends to decrease with age. An American cell phone company has used this to create ring signals that supposedly are only audible to younger humans, but many older people can hear

3955-596: Is generally less than 1 watt per square centimetre to avoid heating and cavitation effects in the object under examination. Ultrasonic imaging applications include industrial nondestructive testing, quality control and medical uses. Acoustic microscopy is the technique of using sound waves to visualize structures too small to be resolved by the human eye. High and ultra high frequencies up to several gigahertz are used in acoustic microscopes. The reflection and diffraction of sound waves from microscopic structures can yield information not available with light. Medical ultrasound

4068-418: Is heard; specif.: a. Psychophysics. Sensation due to stimulation of the auditory nerves and auditory centers of the brain, usually by vibrations transmitted in a material medium, commonly air, affecting the organ of hearing. b. Physics. Vibrational energy which occasions such a sensation. Sound is propagated by progressive longitudinal vibratory disturbances (sound waves)." This means that the correct response to

4181-581: Is made of material that would not transmit the vibration from the window in order to not hear the sound. Land Rover BAR employed 'military' bone conduction technology, designed by BAE Systems , within their helmets for use within the 2017 America's Cup . The helmets allowed the crews to communicate effectively with each other under race conditions and within the harsh, noisy environment; whilst maintaining situational awareness due to their ears being uncovered. In March 2019 at The National Maritime Museum , London, British composer Hollie Harding premiered

4294-421: Is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning, mixing, and accelerating chemical processes. Animals such as bats and porpoises use ultrasound for locating prey and obstacles. Acoustics , the science of sound , starts as far back as Pythagoras in the 6th century BC, who wrote on

4407-465: Is perceived as how "long" or "short" a sound is and relates to onset and offset signals created by nerve responses to sounds. The duration of a sound usually lasts from the time the sound is first noticed until the sound is identified as having changed or ceased. Sometimes this is not directly related to the physical duration of a sound. For example; in a noisy environment, gapped sounds (sounds that stop and start) can sound as if they are continuous because

4520-457: Is perceived as how "low" or "high" a sound is and represents the cyclic, repetitive nature of the vibrations that make up sound. For simple sounds, pitch relates to the frequency of the slowest vibration in the sound (called the fundamental harmonic). In the case of complex sounds, pitch perception can vary. Sometimes individuals identify different pitches for the same sound, based on their personal experience of particular sound patterns. Selection of

4633-422: Is perceptible by humans has frequencies from about 20 Hz to 20,000 Hz. In air at standard temperature and pressure , the corresponding wavelengths of sound waves range from 17 m (56 ft) to 17 mm (0.67 in). Sometimes speed and direction are combined as a velocity vector ; wave number and direction are combined as a wave vector . Transverse waves , also known as shear waves, have

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4746-453: Is used externally in horses for evaluation of soft tissue and tendon injuries, and internally in particular for reproductive work – evaluation of the reproductive tract of the mare and pregnancy detection. It may also be used in an external manner in stallions for evaluation of testicular condition and diameter as well as internally for reproductive evaluation (deferent duct etc.). By 2005, ultrasound technology began to be used by

4859-471: Is used in some types of music. Bone conduction Bone conduction is also called the second auditory pathway and not to be confused with cartilage conduction , which is considered the third auditory pathway. Bone conduction is one reason why a person's voice sounds different to them when it is recorded and played back. Because the skull conducts lower frequencies better than air, people perceive their own voices to be lower and fuller than others do, and

4972-521: The brain . Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20  kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound . Different animal species have varying hearing ranges . Sound

5085-401: The equilibrium pressure, causing local regions of compression and rarefaction , while transverse waves (in solids) are waves of alternating shear stress at right angle to the direction of propagation. Sound waves may be viewed using parabolic mirrors and objects that produce sound. The energy carried by an oscillating sound wave converts back and forth between the potential energy of

5198-483: The hearing range for humans or sometimes it relates to a particular animal. Other species have different ranges of hearing. For example, dogs can perceive vibrations higher than 20 kHz. As a signal perceived by one of the major senses , sound is used by many species for detecting danger , navigation , predation , and communication. Earth's atmosphere , water , and virtually any physical phenomenon , such as fire, rain, wind, surf , or earthquake, produces (and

5311-449: The middle ear —the area between the tympanic membrane (ear drum) and the cochlea (inner ear). If hearing is markedly better through bone conduction than through the ear canal (air-bone gap), problems with the ear canal (e.g. ear wax accumulation), the tympanic membrane or ossicles can be suspected. This method was first discovered by Italian physician Hieronymus Capivacci . The first bone conduction hearing aids were invented in

5424-418: The 15th century. Italian physician Girolamo Cardano realized that when a rod was placed between someone's teeth and attached the other end to a musical instrument, the person could hear the music despite their hearing loss . This method was used by Beethoven , as his hearing deteriorated towards the end of his life. In the 1820s, French physician Jean Marc Gaspard Itard improved on this device by attaching

5537-580: The 1940s by physical and occupational therapists for treating connective tissue : ligaments , tendons , and fascia (and also scar tissue ). Conditions for which ultrasound may be used for treatment include the follow examples: ligament sprains , muscle strains , tendonitis , joint inflammation, plantar fasciitis , metatarsalgia , facet irritation, impingement syndrome , bursitis , rheumatoid arthritis , osteoarthritis , and scar tissue adhesion. Relatively high power ultrasound can break up stony deposits or tissue, increase skin permeability , accelerate

5650-528: The 1960s. Ultrasonic inspection eliminates the use of ionizing radiation, with safety and cost benefits. Ultrasound can also provide additional information such as the depth of flaws in a welded joint. Ultrasonic inspection has progressed from manual methods to computerized systems that automate much of the process. An ultrasonic test of a joint can identify the existence of flaws, measure their size, and identify their location. Not all welded materials are equally amenable to ultrasonic inspection; some materials have

5763-461: The 1970s, a team of doctors in Gothenburg , most notably Anders Tjellström, had the idea to implant a bone vibrator plate into the mastoid bone with an adjoining screw that allowed an external audio processor to be attached to conduct sound. The first three patients were implanted in 1977. The device gave good results and became known as a bone-anchored hearing aid , or BAHA. In 2012, this idea

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5876-453: The MHz range. UHF ultrasound waves have been generated as high as the gigahertz range. Characterizing extremely high-frequency ultrasound poses challenges, as such rapid movement causes waveforms to steepen and form shock waves . The upper frequency limit in humans (approximately 20 kHz) is due to limitations of the middle ear . Auditory sensation can occur if high‐intensity ultrasound

5989-468: The UIT tool, made up of the ultrasonic transducer, pins and other components, comes into contact with the work piece it acoustically couples with the work piece, creating harmonic resonance. This harmonic resonance is performed at a carefully calibrated frequency, to which metals respond very favorably. Depending on the desired effects of treatment a combination of different frequencies and displacement amplitude

6102-404: The additional property, polarization , which is not a characteristic of longitudinal sound waves. The speed of sound depends on the medium the waves pass through, and is a fundamental property of the material. The first significant effort towards measurement of the speed of sound was made by Isaac Newton . He believed the speed of sound in a particular substance was equal to the square root of

6215-400: The audio processor is fixed onto an abutment placed through the skin. The audio processor vibrates, sending the vibrations via the abutment to the implant and then through the bone to the cochlea. The BAHA Attract and Alpha 2 are transcutaneous devices but they work in a similar way. The audio processor vibrates, sending mechanical vibrations to the implant through the bone. However, unlike with

6328-512: The basis of all sound waves. They can be used to describe, in absolute terms, every sound we hear. In order to understand the sound more fully, a complex wave such as the one shown in a blue background on the right of this text, is usually separated into its component parts, which are a combination of various sound wave frequencies (and noise). Sound waves are often simplified to a description in terms of sinusoidal plane waves , which are characterized by these generic properties: Sound that

6441-464: The beef cattle industry to improve animal health and the yield of cattle operations. Ultrasound is used to evaluate fat thickness, rib eye area, and intramuscular fat in living animals. It is also used to evaluate the health and characteristics of unborn calves. Ultrasound technology provides a means for cattle producers to obtain information that can be used to improve the breeding and husbandry of cattle. The technology can be expensive, and it requires

6554-757: The collapse of millions of microscopic cavitation bubbles near the dirty surface. The collapsing bubbles form tiny shockwaves that break up and disperse contaminants on the object's surface. Similar to ultrasonic cleaning, biological cells including bacteria can be disintegrated. High power ultrasound produces cavitation that facilitates particle disintegration or reactions. This has uses in biological science for analytical or chemical purposes ( sonication and sonoporation ) and in killing bacteria in sewage. High power ultrasound can disintegrate corn slurry and enhance liquefaction and saccharification for higher ethanol yield in dry corn milling plants. The ultrasonic humidifier, one type of nebulizer (a device that creates

6667-522: The device being implanted and the health condition of the patient. Non-surgical devices only consist of the external audio processor. The processor simply vibrates, making both the skin and the bone vibrate, conducting the vibrations through to the cochlea . Non-surgical devices are ideal for children, who may not be old enough for implantation surgery or who have temporary conductive hearing loss caused by glue ear or ear infections . There are various ways to attach non-surgical bone conduction devices to

6780-411: The duration of theta wave cycles. This means that at short durations, a very short sound can sound softer than a longer sound even though they are presented at the same intensity level. Past around 200 ms this is no longer the case and the duration of the sound no longer affects the apparent loudness of the sound. Timbre is perceived as the quality of different sounds (e.g. the thud of a fallen rock,

6893-591: The ear and the sound, which can be surprisingly clear and crisp, seems to come from inside the user's head. The Google Glass device employs bone conduction technology for the relay of information to the user through a transducer that sits beside the user's ear. The use of bone conduction means that any vocal content that is received by the Glass user is nearly inaudible to outsiders. German broadcaster Sky Deutschland and advertising agency BBDO Germany collaborated on an advertising campaign that uses bone conduction that

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7006-761: The effect of drugs in a targeted area, assist in the measurement of the elastic properties of tissue, and can be used to sort cells or small particles for research. Ultrasonic impact treatment (UIT) uses ultrasound to enhance the mechanical and physical properties of metals. It is a metallurgical processing technique in which ultrasonic energy is applied to a metal object. Ultrasonic treatment can result in controlled residual compressive stress, grain refinement and grain size reduction. Low and high cycle fatigue are enhanced and have been documented to provide increases up to ten times greater than non-UIT specimens. Additionally, UIT has proven effective in addressing stress corrosion cracking , corrosion fatigue and related issues. When

7119-401: The equation c = γ ⋅ p / ρ {\displaystyle c={\sqrt {\gamma \cdot p/\rho }}} . Since K = γ ⋅ p {\displaystyle K=\gamma \cdot p} , the final equation came up to be c = K / ρ {\displaystyle c={\sqrt {K/\rho }}} , which

7232-439: The extra compression (in case of longitudinal waves) or lateral displacement strain (in case of transverse waves) of the matter, and the kinetic energy of the displacement velocity of particles of the medium. Although there are many complexities relating to the transmission of sounds, at the point of reception (i.e. the ears), sound is readily dividable into two simple elements: pressure and time. These fundamental elements form

7345-406: The fastest in solid atomic hydrogen at about 36,000 m/s (129,600 km/h; 80,530 mph). Sound pressure is the difference, in a given medium, between average local pressure and the pressure in the sound wave. A square of this difference (i.e., a square of the deviation from the equilibrium pressure) is usually averaged over time and/or space, and a square root of this average provides

7458-416: The first time and that the source of sounds could appear to be close to, far from, or all around the listener. Research has found that the use of bone conduction headphones can help people distinguish between their own voice and the voice of others. The findings have potential clinical relevance for conditions such as schizophrenia. Because bone conduction headphones transmit sound to the inner ear through

7571-474: The formation and violent collapse of small vacuum bubbles. This phenomenon is termed cavitation and causes high speed impinging liquid jets and strong hydrodynamic shear-forces. These effects are used for the deagglomeration and milling of micrometre and nanometre-size materials as well as for the disintegration of cells or the mixing of reactants. In this aspect, ultrasonication is an alternative to high-speed mixers and agitator bead mills. Ultrasonic foils under

7684-481: The hearing mechanism that results in the perception of sound. In this case, sound is a sensation . Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration , sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an acoustician , while someone working in the field of acoustical engineering may be called an acoustical engineer . An audio engineer , on

7797-643: The hearing range of humans. The first article on the history of ultrasound was written in 1948. According to its author, during the First World War , a Russian engineer named Chilowski submitted an idea for submarine detection to the French Government. The latter invited Paul Langevin , then Director of the School of Physics and Chemistry in Paris, to evaluate it. Chilowski's proposal was to excite

7910-567: The highest known upper hearing limit at around 160 kHz. Several types of fish can detect ultrasound. In the order Clupeiformes , members of the subfamily Alosinae ( shad ) have been shown to be able to detect sounds up to 180 kHz, while the other subfamilies (e.g. herrings ) can hear only up to 4 kHz. No bird species have been reported to be sensitive to ultrasound. Commercial ultrasonic systems have been sold for supposed indoors electronic pest control and outdoors ultrasonic algae control . However, no scientific evidence exists on

8023-426: The information for timbre identification. Even though a small section of the wave form from each instrument looks very similar, differences in changes over time between the clarinet and the piano are evident in both loudness and harmonic content. Less noticeable are the different noises heard, such as air hisses for the clarinet and hammer strikes for the piano. Sonic texture relates to the number of sound sources and

8136-440: The interaction between them. The word texture , in this context, relates to the cognitive separation of auditory objects. In music, texture is often referred to as the difference between unison , polyphony and homophony , but it can also relate (for example) to a busy cafe; a sound which might be referred to as cacophony . Spatial location represents the cognitive placement of a sound in an environmental context; including

8249-571: The layout of rooms. Although range finding underwater is performed at both sub-audible and audible frequencies for great distances (1 to several kilometers), ultrasonic range finding is used when distances are shorter and the accuracy of the distance measurement is desired to be finer. Ultrasonic measurements may be limited through barrier layers with large salinity, temperature or vortex differentials. Ranging in water varies from about hundreds to thousands of meters, but can be performed with centimeters to meters accuracy Ultrasound Identification (USID)

8362-542: The long-term effects due to ultrasound exposure at diagnostic intensity are still unknown, currently most doctors feel that the benefits to patients outweigh the risks. The ALARA (As Low As Reasonably Achievable) principle has been advocated for an ultrasound examination – that is, keeping the scanning time and power settings as low as possible but consistent with diagnostic imaging – and that by that principle nonmedical uses, which by definition are not necessary, are actively discouraged. Ultrasound

8475-496: The mathematical properties of stringed instruments . Echolocation in bats was discovered by Lazzaro Spallanzani in 1794, when he demonstrated that bats hunted and navigated by inaudible sound, not vision. Francis Galton in 1893 invented the Galton whistle , an adjustable whistle that produced ultrasound, which he used to measure the hearing range of humans and other animals, demonstrating that many animals could hear sounds above

8588-470: The moving wire in a paper machine will use the shock waves from the imploding bubbles to distribute the cellulose fibres more uniformly in the produced paper web, which will make a stronger paper with more even surfaces. Furthermore, chemical reactions benefit from the free radicals created by the cavitation as well as from the energy input and the material transfer through boundary layers. For many processes, this sonochemical (see sonochemistry ) effect leads to

8701-461: The offset messages are missed owing to disruptions from noises in the same general bandwidth. This can be of great benefit in understanding distorted messages such as radio signals that suffer from interference, as (owing to this effect) the message is heard as if it was continuous. Loudness is perceived as how "loud" or "soft" a sound is and relates to the totalled number of auditory nerve stimulations over short cyclic time periods, most likely over

8814-542: The operation of a larger ultrasonic horn. A researcher at the Industrial Materials Research Institute, Alessandro Malutta, devised an experiment that demonstrated the trapping action of ultrasonic standing waves on wood pulp fibers diluted in water and their parallel orienting into the equidistant pressure planes. The time to orient the fibers in equidistant planes is measured with a laser and an electro-optical sensor. This could provide

8927-449: The other end of the rod not to a musical instrument but to the mouth of another speaker. This invention was known as the Rod of Itard. In 1923, Hugo Gernsback created a new kind of bone conduction hearing aid called the "Osophone", which he later elaborated on with his "Phonosone". Bone conduction hearing aids have also been fitted to glasses, which fit tightly to the side of the head. In

9040-482: The other hand, is concerned with the recording, manipulation, mixing, and reproduction of sound. Applications of acoustics are found in almost all aspects of modern society, subdisciplines include aeroacoustics , audio signal processing , architectural acoustics , bioacoustics , electro-acoustics, environmental noise , musical acoustics , noise control , psychoacoustics , speech , ultrasound , underwater acoustics , and vibration . Sound can propagate through

9153-778: The paper industry a quick on-line fiber size measurement system. A somewhat different implementation was demonstrated at Pennsylvania State University using a microchip which generated a pair of perpendicular standing surface acoustic waves allowing to position particles equidistant to each other on a grid. This experiment, called acoustic tweezers , can be used for applications in material sciences, biology, physics, chemistry and nanotechnology. Ultrasonic cleaners , sometimes mistakenly called supersonic cleaners , are used at frequencies from 20 to 40 kHz for jewellery, lenses and other optical parts, watches, dental instruments , surgical instruments , diving regulators and industrial parts. An ultrasonic cleaner works mostly by energy released from

9266-470: The percutaneous devices, the vibrations from the audio processor pass through the skin before they reach the internal implant. These vibrations are then conducted through the skull bones to the cochlea and are processed as normal, just like with an active device. Active transcutaneous and passive percutaneous bone conduction devices tend to deliver better sound quality than passive transcutaneous ones. Passive transcutaneous devices send sound vibrations through

9379-580: The placement of a sound on both the horizontal and vertical plane, the distance from the sound source and the characteristics of the sonic environment. In a thick texture, it is possible to identify multiple sound sources using a combination of spatial location and timbre identification. Ultrasound is sound waves with frequencies higher than 20,000 Hz. Ultrasound is not different from audible sound in its physical properties, but cannot be heard by humans. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. Medical ultrasound

9492-562: The pressure acting on it divided by its density: This was later proven wrong and the French mathematician Laplace corrected the formula by deducing that the phenomenon of sound travelling is not isothermal, as believed by Newton, but adiabatic . He added another factor to the equation— gamma —and multiplied γ {\displaystyle {\sqrt {\gamma }}} by p / ρ {\displaystyle {\sqrt {p/\rho }}} , thus coming up with

9605-423: The production of harmonics and mixed tones not present in the original sound (see parametric array ). If relativistic effects are important, the speed of sound is calculated from the relativistic Euler equations . In fresh water the speed of sound is approximately 1,482 m/s (5,335 km/h; 3,315 mph). In steel, the speed of sound is about 5,960 m/s (21,460 km/h; 13,330 mph). Sound moves

9718-555: The question: " if a tree falls in a forest and no one is around to hear it, does it make a sound? " is "yes", and "no", dependent on whether being answered using the physical, or the psychophysical definition, respectively. The physical reception of sound in any hearing organism is limited to a range of frequencies. Humans normally hear sound frequencies between approximately 20  Hz and 20,000 Hz (20  kHz ), The upper limit decreases with age. Sometimes sound refers to only those vibrations with frequencies that are within

9831-423: The required ultrasonic exposure parameters. After this phase is complete, the process is transferred to a pilot (bench) scale for flow-through pre-production optimization and then to an industrial scale for continuous production. During these scale-up steps, it is essential to make sure that all local exposure conditions (ultrasonic amplitude, cavitation intensity, time spent in the active cavitation zone, etc.) stay

9944-443: The response of the human ear to noise and A-weighted sound pressure levels are labeled dBA. C-weighting is used to measure peak levels. A distinct use of the term sound from its use in physics is that in physiology and psychology, where the term refers to the subject of perception by the brain. The field of psychoacoustics is dedicated to such studies. Webster's dictionary defined sound as: "1. The sensation of hearing, that which

10057-480: The same. If this condition is met, the quality of the final product remains at the optimized level, while the productivity is increased by a predictable "scale-up factor". The productivity increase results from the fact that laboratory, bench and industrial-scale ultrasonic processor systems incorporate progressively larger ultrasonic horns , able to generate progressively larger high-intensity cavitation zones and, therefore, to process more material per unit of time. This

10170-517: The signals, which may be because of the considerable variation of age-related deterioration in the upper hearing threshold. Bats use a variety of ultrasonic ranging ( echolocation ) techniques to detect their prey. They can detect frequencies beyond 100 kHz, possibly up to 200 kHz. Many insects have good ultrasonic hearing, and most of these are nocturnal insects listening for echolocating bats. These include many groups of moths , beetles , praying mantises and lacewings . Upon hearing

10283-573: The skin to the internal implant, which directly and actively vibrates the bone. These vibrations are conducted through the skull bone to the cochlea and are processed as normal. The main passive bone conduction devices are the BAHA Attract and BAHA Connect from Cochlear, the Ponto from Oticon and the Alpha 2 MPO from Medtronic . The BAHA Connect and Ponto are passive percutaneous devices, whereby

10396-716: The skin, and as they pass through the skin, they lose some of their strength, causing signal attenuation of up to 20 dB . To counteract this, passive transcutaneous devices may require the use of strong magnets that squeeze the skin to achieve optimal conduction. This can lead to pain and irritation of the skin and soft tissue between the two magnets, and in worst cases cause necrosis . A study found that major complications — defined as complications requiring active management, such as post-operative seroma , hematoma , wound infections, skin ulcerations , and dehiscence — were found in 5.2% of cases. Bone conduction products are usually categorized into three groups: One example of

10509-755: The skin, including headbands , adhesives and bone conduction glasses. Devices include the ADHEAR from MED-EL , the BAHA Start from Cochlear , BHM's contact mini or contact forte and the Ponto Softband from Oticon Medical . Unlike headbands or glasses-based devices, adhesive devices do not need to apply pressure against the head in order to transmit the vibration. Because of this, users of adhesive devices report wearing their device for longer each day. A transcutaneous bone conduction device transmits sound signals, either electronic or mechanical, through

10622-415: The skin. In other words, there is closed, intact skin between the external audio processor and the internal implant. The processor is held in place over the implant using magnetic attraction . Transcutaneous devices currently on the market include the BAHA Attract, and Osia from Cochlear and the BONEBRIDGE from MED-EL. With a percutaneous device, part of the implant (known as the abutment) protrudes through

10735-603: The skin. The audio processor then snaps onto the abutment, providing a direct connection to the implant. Percutaneous devices include the BAHA Connect from Cochlear and the Ponto from Oticon Medical. Percutaneous devices have been associated with skin complications, ranging from slight redness to the formation of granulation tissue and recurring infection. The most serious complications might require further surgery or abutment removal and subsequent reimplantation. One study into skin problems with percutaneous implants revealed

10848-528: The sound is called the medium . Sound cannot travel through a vacuum . Studies has shown that sound waves are able to carry a tiny amount of mass and is surrounded by a weak gravitational field. Sound is transmitted through gases, plasma, and liquids as longitudinal waves , also called compression waves. It requires a medium to propagate. Through solids, however, it can be transmitted as both longitudinal waves and transverse waves . Longitudinal sound waves are waves of alternating pressure deviations from

10961-420: The sound wave. At a fixed distance from the source, the pressure , velocity , and displacement of the medium vary in time. At an instant in time, the pressure, velocity, and displacement vary in space. The particles of the medium do not travel with the sound wave. This is intuitively obvious for a solid, and the same is true for liquids and gases (that is, the vibrations of particles in the gas or liquid transport

11074-417: The speed of sound in gases depends on temperature. In 20 °C (68 °F) air at sea level, the speed of sound is approximately 343 m/s (1,230 km/h; 767 mph) using the formula v  [m/s] = 331 + 0.6  T  [°C] . The speed of sound is also slightly sensitive, being subject to a second-order anharmonic effect, to the sound amplitude, which means there are non-linear propagation effects, such as

11187-418: The success of such devices for these purposes. An ultrasonic level or sensing system requires no contact with the target. For many processes in the medical, pharmaceutical, military and general industries this is an advantage over inline sensors that may contaminate the liquids inside a vessel or tube or that may be clogged by the product. Both continuous wave and pulsed systems are used. The principle behind

11300-547: The thickness of objects. Frequencies of 2 to 10 MHz are common, but for special purposes other frequencies are used. Inspection may be manual or automated and is an essential part of modern manufacturing processes. Most metals can be inspected as well as plastics and aerospace composites . Lower frequency ultrasound (50–500 kHz) can also be used to inspect less dense materials such as wood, concrete and cement . Ultrasound inspection of welded joints has been an alternative to radiography for nondestructive testing since

11413-495: The transmitter as an echo and can be detected through the receiver path. By measuring the difference in time between the pulse being transmitted and the echo being received, it is possible to determine the distance. The measured travel time of Sonar pulses in water is strongly dependent on the temperature and the salinity of the water. Ultrasonic ranging is also applied for measurement in air and for short distances. For example, hand-held ultrasonic measuring tools can rapidly measure

11526-467: The ultrasound can cover a wide area from a single point. The flow in pipes or open channels can be measured by ultrasonic flowmeters, which measure the average velocity of flowing liquid. In rheology , an acoustic rheometer relies on the principle of ultrasound. In fluid mechanics , fluid flow can be measured using an ultrasonic flow meter . Ultrasonic testing is a type of nondestructive testing commonly used to find flaws in materials and to measure

11639-589: The ultrasound; the top end of a dog's hearing range is about 45 kHz, while a cat's is 64 kHz. The wild ancestors of cats and dogs evolved this higher hearing range to hear high-frequency sounds made by their preferred prey, small rodents. A dog whistle is a whistle that emits ultrasound, used for training and calling dogs. The frequency of most dog whistles is within the range of 23 to 54 kHz. Toothed whales , including dolphins , can hear ultrasound and use such sounds in their navigational system ( biosonar ) to orient and to capture prey. Porpoises have

11752-408: The use of Bone Conduction Headphones as part of a musical performance. The use of the technology allowed the audience to listen to a pre-recorded musical track on the headsets, whilst a live orchestra performed a separate but related musical track. This multilayered effect meant that electronic and digitally-edited sounds could be heard in conjunction with live music without the use of loud-speakers for

11865-433: The vibrations and sends them to the auditory cortex in the brain. Different bone conduction devices contain different features. Here are the key ones. Surgical bone conduction devices consist of an internal implant and an external audio processor used to transmit sound. They require surgery in order to implant the device, which is usually done as an outpatient procedure under general anesthetic , however this depends on

11978-566: The vibrations, while the average position of the particles over time does not change). During propagation, waves can be reflected , refracted , or attenuated by the medium. The behavior of sound propagation is generally affected by three things: When sound is moving through a medium that does not have constant physical properties, it may be refracted (either dispersed or focused). The mechanical vibrations that can be interpreted as sound can travel through all forms of matter : gases, liquids, solids, and plasmas . The matter that supports

12091-430: The whir of a drill, the tone of a musical instrument or the quality of a voice) and represents the pre-conscious allocation of a sonic identity to a sound (e.g. "it's an oboe!"). This identity is based on information gained from frequency transients, noisiness, unsteadiness, perceived pitch and the spread and intensity of overtones in the sound over an extended time frame. The way a sound changes over time provides most of

12204-434: Was built by Sir Charles Parsons , the inventor of the vapour turbine , but the device was found not to be suitable for this purpose. Langevin's device made use of the piezoelectric effect , which he had been acquainted with whilst a student at the laboratory of Jacques and Pierre Curie . Langevin calculated and built an ultrasound transducer comprising a thin sheet of quartz sandwiched between two steel plates. Langevin

12317-457: Was famously rumored to be using bone conduction after losing most of his hearing, by placing one end of a rod in his mouth and resting the other end on the rim of his piano. It has also been observed that some animals can perceive sound and even communicate by sending and receiving vibration through bone. Comparison of hearing sensitivity through bone conduction and directly through the ear canal can aid audiologists in identifying pathologies of

12430-588: Was premiered in Cannes, France at the International Festival of Creativity in June 2013. The "Talking Window" advertising concept uses bone conduction to transmit advertising to public transport passengers who lean their heads against train glass windows. Academics from Australia's Macquarie University suggested that, apart from not touching the window, passengers would need to use a dampening device that

12543-426: Was taken a step further by the introduction of the BONEBRIDGE device. Whereas a BAHA implant is a percutaneous device that requires the screw abutment to protrude through the skin, the BONEBRIDGE is a transcutaneous device and is fully implanted under the skin. In this case, the audio processor is held in place by magnets. Bone conduction devices are suitable for patients with conductive or mixed hearing loss , with

12656-481: Was the Polaroid SX-70 camera, which included a lightweight transducer system to focus the camera automatically. Polaroid later licensed this ultrasound technology and it became the basis of a variety of ultrasonic products. A common ultrasound application is an automatic door opener, where an ultrasonic sensor detects a person's approach and opens the door. Ultrasonic sensors are also used to detect intruders;

12769-578: Was the first to report cavitation -related bioeffects from ultrasound. Ultrasound is defined by the American National Standards Institute as " sound at frequencies greater than 20 kHz". In air at atmospheric pressure, ultrasonic waves have wavelengths of 1.9 cm or less. Ultrasound can be generated at very high frequencies; ultrasound is used for sonochemistry at frequencies up to multiple hundreds of kilohertz. Medical imaging equipment uses frequencies in

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