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from the "can-you-hear-me-now"-is-too-cliche-of-a dept.
Ever wondered if you've hurt your ears? Too much rock 'n roll, or too many loud race cars? Just discovered this over-the-phone test which is offered free this month in USA, call 866-223-7575.
More info at nationalhearingtest.org:
The critical difference between the NHT and other telephone tests is that the NHT uses digits in noise, rather than pure tones. Previous objections to telephone-administered tests were based on the unreliability of pure-tone tests administered over the telephone. Because the NHT measures an SNR threshold, rather than one based on the absolute level of tones, the NHT can produce a reliable screening measure of hearing, despite the differences in sound levels produced by different telephones.
Scientists at VU University Medical Center in the Netherlands developed the first telephone hearing screenings based on spoken digits in noise. The Dutch National Hearing Test was introduced in 2004 and has since served as a model for similar tests throughout Europe and Australia. The United Kingdom, Denmark, France, Germany, Poland, Switzerland, Spain, and Australia have developed and introduced their own versions of a telephone hearing screening, all using digit sequences presented in noise. The growing popularity of this form of screening test is due in part to its demonstrated validity and reliability. Testing by telephone is also a convenient, inexpensive way to determine whether a person's functional hearing is within the normal range.
(Score: 2) by hankwang on Monday May 12 2014, @07:32AM
"It's kinda arbitrary, though, to use a female voice and a specific noise spectrum"
They claim that the test results are highly correlated to those of traditional tests (threshold of hearing over a frequency range). I'm sure they tested a lot of voices and noise spectra in order to find the parameters that produce the highest correlation.
Typically, hearing damage starts in the 2--5 kHz range, where the ear is most sensitive and at the frequencies that are most useful to distinguish consonants and vowels from each other. It's an interesting question why SNR threshold at high SPL would be correlated to loss of absolute threshold. Suppose the signal is S and the threshold of hearing is T. With an added noise N, the overall SNR is S/(T+N). If the test subject's loudspeaker has an unknownn volume gain g, then
SNR=S/(T/g + N).
The quantity they're after is T, which cannot be solved for. So, hearing is a bit more complex than this, if this test still produces valid results.
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