Ultrasonic hearing

Ultrasonic hearing

Ultrasonic hearing is a recognised auditory effect which allows humans to perceive sounds of a much higher frequency than would ordinarily be audible using the physical inner ear, usually by stimulation of the base of the cochlea through bone induction. Human hearing is recognised as having an upper bound around 17-20 kHz, depending on the person, but ultrasonic sinusoids as high as 120 kHz have been reported as successfully perceived.

Two competing theories are proposed to explain this effect. The first [cite journal
last = Nishimura
first = T.
coauthors = Nakagawa, S.,Sakaguchi, T.
year = 2003
month = January
title = Ultrasonic masker clarifies ultrasonic perception in man
journal = Hearing Research
volume = 175
pages = 171–177
doi = 10.1016/S0378-5955(02)00735-9 ] asserts that ultrasonic sounds excite the inner hair cells of the cochlea basal turn, which are responsive to high frequency sounds. The second [cite journal
last = Lenhardt
first = M.
date =
year = 2003
month =
title = Ultrasonic hearing in humans: applications for tinnitus treatment
journal = Int. Tinnitus J.
volume = 9
issue = 2
pages = 69–75
issn =
pmid =
doi =
id =
url = http://www.tinnitus.vcu.edu/Pages/Ultrasonic%20Hearing.pdf
language =
format =
accessdate =
laysummary =
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quote = ] proposed that ultrasonic signals resonate the brain and are modulated down to frequencies that the cochlea can then detect.

By modulating speech signals onto an ultrasonic carrier, intelligible speech has also been perceived with a high degree of clarity, especially in areas of high noise. Deatherage [cite journal
last = Deatherage
first = B.
coauthors = Jeffress, L., Blodgett, H.
year = 1954
title = A Note on the Audibility of Intense Ultrasonic Sound
journal = J. Acoustic Soc. Am.
volume = 26
issue = 582
pages =
issn =
pmid =
doi = 10.1121/1.1907379
id =
url =
language =
format =
accessdate =
laysummary =
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quote = ] states that what humans experience as ultrasonic perception may have been a necessary precursor in the evolution of echolocation in marine mammals.

References

ee also

* Hypersonic effect


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