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It is approximately the quietest sound a young human with undamaged hearing can detect at 1 kHz. [4] The threshold of hearing is frequency-dependent and it has been shown that the ear's sensitivity is best at frequencies between 2 kHz and 5 kHz, [5] where the threshold reaches as low as −9 dB SPL. [6] [7] [8]
This is done by temporarily elevating the threshold of the non-test ear, by presenting a masking noise at a predetermined level. This prevents the non-test ear from detecting the test signal presented to the test ear. The threshold of the test ear is measured at the same time as presenting the masking noise to the non-test ear.
A tone at the frequency of 4000 Hz is presented for 60 seconds at an intensity of 5 decibels above the patient's absolute threshold of hearing. If the patient stops hearing the tone before 60 seconds, the intensity level is increased by another 5 decibels with the procedure repeated until the tone can be heard for the full 60 seconds or until no decibel level can be found where the tone can be ...
The pressure at which sound becomes painful for a listener is the pain threshold pressure for that person at that time. The threshold pressure for sound varies with frequency and can be age-dependent. People who have been exposed to more noise/music usually have a higher threshold pressure. [3] Threshold shift can also cause threshold pressure ...
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.
The measured curves for pure tones, for instance, are different from those for random noise. The ear also responds less well to short bursts, below 100 to 200 ms, than to continuous sounds [1] such that a quasi-peak detector has been found to give the most representative results when noise contains click or bursts, as is often the case for ...
The ear can be exposed to short periods of sound in excess of 120 dB without permanent harm — albeit with discomfort and possibly pain — but long term exposure to sound levels over 85 dB(A) can cause permanent hearing loss. [31] There are two basic types of NIHL: NIHL caused by acoustic trauma; NIHL that gradually develops.
The human auditory system is sensitive to frequencies from about 20 Hz to a maximum of around 20,000 Hz, although the upper hearing limit decreases with age. Within this range, the human ear is most sensitive between 2 and 5 kHz, largely due to the resonance of the ear canal and the transfer function of the ossicles of the middle ear.