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An audio frequency or audible frequency (AF) is a periodic vibration whose frequency is audible to the average human. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch. [1] The generally accepted standard hearing range for humans is 20 to 20,000 Hz.
Humans normally hear sound frequencies between approximately 20 Hz and 20,000 Hz (20 kHz), [18]: 382 The upper limit decreases with age. [18]: 249 Sometimes sound refers to only those vibrations with frequencies that are within the hearing range for humans [19] or sometimes it relates to a particular animal. Other species have different ranges ...
Sound propagates as mechanical vibration waves of pressure and displacement, in air or other substances. [10] In general, frequency components of a sound determine its "color", its timbre. When speaking about the frequency (in singular) of a sound, it means the property that most determines its pitch. [11]
Both of these popular methods are used to analyze sound and better understand the acoustic phenomenon. The entire spectrum can be divided into three sections: audio, ultrasonic, and infrasonic. The audio range falls between 20 Hz and 20,000 Hz. This range is important because its frequencies can be detected by the human ear.
When the subject hears the sound, they indicate this by raising a hand or pressing a button. The lowest intensity they can hear is recorded. The test varies for children; their response to the sound can be indicated by a turn of the head or by using a toy. The child learns what to do upon hearing the sound, such as placing a toy man in a boat.
In telephony, the usable voice frequency band ranges from approximately 300 to 3400 Hz. [2] It is for this reason that the ultra low frequency band of the electromagnetic spectrum between 300 and 3000 Hz is also referred to as voice frequency, being the electromagnetic energy that represents acoustic energy at baseband.
Sound spectrum: High frequencies are more quickly damped by the air than low frequencies. Therefore, a distant sound source sounds more muffled than a close one, because the high frequencies are attenuated. For sound with a known spectrum (e.g. speech) the distance can be estimated roughly with the help of the perceived sound.
Pure tone – Sound with a sinusoidal waveform; Pythagorean tuning – Method of tuning a musical instrument; Scale of harmonics; Spherical harmonics – Special mathematical functions defined on the surface of a sphere; Stretched octave; Subharmonic – Having a frequency that is a fraction of a fundamental frequency