Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 55. Chapters: Hearing impairment, Ambient noise level, Quiet PC, Awaaz Foundation, Health effects from noise, SoundMorePlease note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.
Pages: 55. Chapters: Hearing impairment, Ambient noise level, Quiet PC, Awaaz Foundation, Health effects from noise, Sound level meter, Noise regulation, A-weighting, Lombard effect, Noise mitigation, The Hum, Aircraft noise, Noise dosimeter, Audiometer, Roadway noise, Noise barrier, Silent disco, Line source, Noise map, Loud music, Noise Free America, Quota Count system, Audiometry, Noise control, Sound baffle, Industrial noise, Buy Quiet, Noise Control Act, Noise measurement, Train noise, Environmental noise, Association of Noise Consultants.
Excerpt: Deafness is a condition wherein the ability to detect certain frequencies of sound is completely or partially impaired. When applied to humans, the term hearing impaired is rejected by the deaf culture movement, where the terms deaf and hard-of-hearing are preferred. Hearing sensitivity is indicated by the quietest sound that an animal can detect, called the hearing threshold.
In the case of humans and some animals, this threshold can be accurately measured by a behavioral audiogram. A record is made of the quietest sound that consistently prompts a response from the listener. The test is carried out for sounds of different frequencies. There are also electro-physiological tests that can be performed without requiring a behavioral response. Normal hearing thresholds within any given species are not the same for all frequencies. If different frequencies of sound are played at the same amplitude, some will be perceived as loud, and others quiet or even completely inaudible.
Generally, if the gain or amplitude is increased, a sound is more likely to be perceived. Ordinarily, when animals use sound to communicate, hearing in that type of animal is most sensitive for the frequencies produced by calls, or in the case of humans, speech. All levels of the auditory system contribute to this sensi...