Longitudinal waves and sound

Clinical and other applications of ultrasound

Clinical and other applications of ultrasound Ultrasonic waves are being increasingly used in medical and surgical diagnosis by a technique based on the fact that different types of tissue, e.g., bone, fat, and muscle  have different reflective properties for very high-frequency waves. When a portion of the body is scanned by an ultrasonic beam, the varying echoes are …

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Anechoic and soundproof rooms

Anechoic and soundproof rooms For certain special purposes, e.g., investigation of the properties of loud-speakers and other sound equipment, it is necessary to have rooms whose walls absorb completely all sound energy falling upon them. This is achieved by lining the walls, ceiling, and’ floor with anechoic (= without echo) wedges composed of glass fibre, or plastic foam, encased …

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The acoustics of buildings

The acoustics of buildings Reverberation is particularly noticeable in cathedrals and other large buildings where multiple sound reflections can occur from walls, roof and floor. For example, in St. Paul’s Cathedral, London, it takes about 6 seconds for the notes of the organ to die away after the organist has stopped playing. Excessive reverberation in a concert hall …

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Echoes

Echoes Echoes are produced by the reflection of sound from a hard surface such as a wall or cliff. Let us suppose that a person claps his hands when standing some distance from a high wall and listens for the echo. The time which elapses before the echo arrives will depend on the distance away of the wall. …

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Sound waves

Sound waves Sound waves in air differ from the transverse waves described in the previous chapter in that the wave particles oscillate in the same direction as the wave instead of at right angles to it. Waves of this type are called longitudinal waves. Owing to the longitudinal motion of the wave particles, sound waves consist of a …

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