Some patients have reported a shift in auditory input pitch while doing heavy physical activity. The shift only occurs for a second or so. Could it be influenced by increased pressure, decreased bloodflow, or more intrestingly by the brain?
I am by no means an audio perception expert, but I'd suspect that perhaps it has to do with external pressure on the cochlea (or some other part of the inner or middle ear) causing a small but perceptible shift in the locations stimulated by sounds of particular frequencies. I had a similar experience once when having a sever sinus infection. All sounds on the affected side were noticeably at a high pitch that those in the opposite ear. It was most noticeable when listening to pure tones and music. A very strange experience indeed. This is just a guess, of course.
"A very strange experience indeed. This is just a guess, of course."
And a good guess at that. Meniere Spectrum Disorder is a very common but unsuspected and misdiagnosed condition. Its pathological basis is endolymphatic hydrops, which I believe is triggered by any drop in perilymphatic pressure inside the inner ear, as may result from drops in CSF pressure, or fluid loss from the cranial lymphatic system as may occur with colds or sinusitis. An early and prominent symptom is diplacusis or pitch distortion, which would often be the presenting symptom in musicians. Another symptom is audiosensitivity, which I think is due to a mechanical shift inside the cochlea. The strangest and most characteristic symptom of MSD is a feeling of fullness, pressure or blockage in the ear/head. It is much more interesting when these strange symptoms turn out to originate in the ear and not the brain!
Change pitch perception by will? Yes! Try this: turn on a sinewave generator, then bite your teeth quite hard together. The loudness changes, and (likely due to that), the perceived pitch. You can also shake your head to create a nice pitch-vibrato (Doppler effect).
"Change pitch perception by will? Yes!"
If this is a general phenomenon, and not just an idiosyncratic reaction in someone with an unusual anatomy, it should be written up and published in a leading scientific journal. It should help explain the otherwise mysterious connection between the temporomandibular joint syndrome (Costen) and Meniere Spectrum Disorder.
@Anthony: You are right, I've only tested myself using simple means, and I've no idea how general the phenomenon might be. The effect is quite clear to me, in particular for higher frequencies (> 1500 Hz) where pitch rises when biting, but it's by not more than a quarter-tone. That pitch depends on sound level was known by S. Stevens (1930s), however at present there doesn't seem to be a generally accepted explanation for the phenomenon. Place theory doesn't account fully (see B. Moore: Psychology of Hearing, 6th ed. p. 213-4). But in the first place, is it certain that clenching one's teeth increases sound level? I'm thinking that biting increases the tension in soft tissues in middle ear, which affects (how?) the ossicles' mechanical amplification, which leads to increased acoustic sound level at the oval window. This is for normal (non-pathological) hearing. The connection Costen/Meniere is intriguing.
"biting increases the tension in soft tissues in middle ear"
In which case, the tension in the tensor tympani and stapedius muscles would increase, which in a normal ear would decrease the loudness of an external sound. I am pretty sure that Meniere Spectrum Disorder is due to a drop of perilymphatic pressure. One can probably rustle up an ad hoc explanation as to why jaw movements could decrease the inner ear pressure. Diplacusis, audiosensitivity and a sensation of pressure in the ear are very early symptoms of MSD.
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