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

Abstract

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 nerval stimulation. But through this mechanical pre-processing step the amplitude becomes high enough to be recognised as a signal by the outer hair cells.

Key Words:

• pitch
• cochlear sound projection
• inner ear mechanics
• hearing theory