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For waves on a string, or in a medium such as water, the amplitude is a displacement. The amplitude of sound waves and audio signals (which relates to the volume) conventionally refers to the amplitude of the air pressure in the wave, but sometimes the amplitude of the displacement (movements of the air or the diaphragm of a speaker) is described.
Amplitude is the size (magnitude) of the pressure variations in a sound wave, and primarily determines the loudness with which the sound is perceived. In a sinusoidal function such as C sin ( 2 π f t ) {\displaystyle C\sin(2\pi ft)} , C represents the amplitude of the sound wave.
Depending on context, wave height may be defined in different ways: For a sine wave, the wave height H is twice the amplitude (i.e., the peak-to-peak amplitude): [1] =.; For a periodic wave, it is simply the difference between the maximum and minimum of the surface elevation z = η(x – c p t): [1] = {()} {()}, with c p the phase speed (or propagation speed) of the wave.
20 Hz is considered the normal low-frequency limit of human hearing. When pure sine waves are reproduced under ideal conditions and at very high volume, a human listener will be able to identify tones as low as 12 Hz. [38] Below 10 Hz it is possible to perceive the single cycles of the sound, along with a sensation of pressure at the eardrums.
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave.In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal.
Sound intensity, also known as acoustic intensity, is defined as the power carried by sound waves per unit area in a direction perpendicular to that area, also called the sound power density and the sound energy flux density. [2] The SI unit of intensity, which includes sound intensity, is the watt per square meter (W/m 2).
Such a relaxed definition of whispering (i.e., production of short-range, low-amplitude acoustic signals which are significantly different than those produced at high amplitude) cannot be applied to humans without including vocalizations distinct from human whispering (e.g., creaky voice, and falsetto). Further research is needed to ascertain ...
[2] [3] [4] In air at atmospheric pressure, these represent sound waves with wavelengths of 17 metres (56 ft) to 1.7 centimetres (0.67 in). Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. Sound frequencies above 20 kHz are called ultrasonic.