LING 2P90 Lecture Notes - Lecture 21: Nasal Septum Deviation, Acoustic Impedance, Nasal Cavity
7 Dec 2014
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Vp-n airway resistance: opposition to flow of air across: Examples: nasal cavity tissues engorged (due to cold, allergies, deviated nasal septum (leads to increased vp-n airway resistance through one naris) Velopharyngeal sphincter compression: goal: maintain vp port closure, process: muscular pressure (from levator palatini and uvular muscles) must exceed air pressure difference across vp port. Vp-n acoustic impedance: opposition to flow of acoustic (sound) energy throughout vp-n apparatus, vp port closure re-routes acoustic energy from being shared between pharangeal oral and velopharyngeal nasal pathways. Impedance to acoustic energy flow across vp port becomes very high. Acoustic energy now moves through pharyngeal oral apparatus only: example of reduced acoustic impedance. Prevent complete vp closure; acoustic energy no longer impeded from travelling across vp port. May require pharyngeal flap surgery to permit vp port closure during speech. Flap of mucous membrane and muscle take from posterior pharyngeal wall (ppw) and sutured to velum: example of too much acoustic impedance.
