Acoustical characteristics of surgically altered human temporal bones.
The resonance qualities of the external auditory canal can increase the sound pressure level (SPL) at the tympanic membrane by as much as 20 dB between 2 and 4 kHz. Surgery on the canal, particularly in the form of a modified radical mastoidectomy, might be expected to affect this with resultant implications for speech discrimination. The creation of a modified radical mastoidectomy in 6 temporal bones altered the SPL at the tympanic membrane by +10 dB at 2 kHz, +14 dB at 2.5 kHz, -2 dB at 3 kHz, -12 dB at 3.5 kHz, -20 dB at 4 kHz, -16 dB at 5 kHz and -8 dB at 6 kHz. When this transfer function was applied to 2 subjects, speech discrimination in noise was reduced by 6%. Whether this is of any magnitude compared with the effect of the disease requires prospective studies in individuals undergoing a modified radical mastoidectomy.
D000162:Acoustics; D001844:Bone Conduction; D004424:Ear Canal / Q000503:physiopathology; D006801:Humans; D008416:Mastoid / Q000601:surgery; D010033:Otitis Media / Q000601:surgery; D013701:Temporal Bone / Q000503:physiopathology* / Q000601:surgery