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The absolute threshold of hearing (ATH), also known as the absolute hearing threshold or auditory threshold, is the minimum sound level of a pure tone that an average human ear with normal hearing can hear with no other sound present. The absolute threshold relates to the sound that can just be heard by the organism.
[6] [7] [note 1] Under ideal laboratory conditions, humans can hear sound as low as 12 Hz [8] and as high as 28 kHz, though the threshold increases sharply at 15 kHz in adults, corresponding to the last auditory channel of the cochlea. [9] The human auditory system is most sensitive to frequencies between 2,000 and 5,000 Hz. [10]
When sensorineural hearing loss (damage to the cochlea or in the brain) is present, the perception of loudness is altered. Sounds at low levels (often perceived by those without hearing loss as relatively quiet) are no longer audible to the hearing impaired, but sounds at high levels often are perceived as having the same loudness as they would for an unimpaired listener.
When the testee hears the sound he or she responds (e.g., by raising a hand or pressing a button. The tester records the lowest intensity sound the testee can hear. With children, an audiologist makes a game out of the hearing test by replacing the feedback device with activity-related toys such as blocks or pegs.
20 micro-Pascals is called the Threshold of human hearing, and is equal to 0 dB Sound pressure level (SPL). ITU-T recommendation P.79 [ 1 ] has the frequency weighted sensitivity calculations in it for sending loudness rating (SLR) and receive loudness rating (RLR) for telephony.
the speech may sound "choppy" (see noise gate) and difficult to understand the sudden change in sound level can be jarring to the listener. To counteract these effects, comfort noise is added, usually on the receiving end in wireless or VoIP systems, to fill in the silent portions of transmissions with artificial noise.
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. [6] Higher pitches have higher frequency, and lower pitches are lower frequency. The frequencies an ear can hear are limited to a specific range of ...
The human ear can nominally hear sounds in the range 20 to 20 000 Hz. The upper limit tends to decrease with age; most adults are unable to hear above 16 000 Hz. Under ideal laboratory conditions, the lowest frequency that has been identified as a musical tone is 12 Hz. [6] Tones between 4 and 16 Hz can be perceived via the body's sense of touch.