Pitch is influenced by differences in gas pressure between the middle ear and the external auditory canal. A tentative explanation based on a new aspect in inner ear theory.
When the pressure in the external auditory canal is changed (as during tympanometry), the pitch rises by about 6 Hz on average (at +/- 400 mm H2O). Apparently, the travelling wave breaks earlier, as impedance increases, with the sound being projected to a site farther basal. At this site a vibration at the local resonant frequency is elicited. In keeping with the chaos theory, its amplitude is amplified by self-organisation. This is a purely mechanical process which does not involve perception in terms of neural stimulation. But through this mechanical pre-processing step the amplitude becomes high enough to be recognised as a signal by the outer hair cells.
Fritze
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ENT Department, University of Vienna Medical School, Austria.
D000158:Acoustic Impedance Tests; D000162:Acoustics; D000328:Adult; D004424:Ear Canal / Q000502:physiology*; D007758:Ear, Inner / Q000502:physiology; D004432:Ear, Middle / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010898:Pitch Perception / Q000502:physiology*; D011312:Pressure