Sound Pressure Distribution in the Ear After Radical Mastoidectomy With Meatoplasty

Abstract

Objective: We aimed to identify the sound pressure distribution along the external auditory canal after radical mastoidectomy with meatoplasty by combining real ear measurements and measurements obtained using a finite-element model.

Study design: Case series with chart review.

Setting: Tertiary care university hospital.

Patients: We evaluated 16 patients who had undergone radical mastoidectomy with meatoplasty in one ear and had intact nonoperated contralateral ears, which served as the control group.

Intervention diagnostic: Real ear measurements testing at specific frequencies were performed postoperatively.

Main outcome measure: Sound pressure gains were measured at five different depths along the external auditory canal, and a validated finite-element model was used to simulate the sound pressure distributions along the external auditory canals of the operated and nonoperated ears.

Results: The average peak resonant frequency near the tympanic membrane in operated ears was significantly lesser than that in nonoperated ears (2434.4 ± 616.4 versus 2935.9 ± 602.2 Hz; Wilcoxon signed-rank test, p < 0.05). The average peak resonant amplitude near the tympanic membrane showed no significant intergroup difference (paired-sample t test, p > 0.05). The peak resonant frequencies at different depths of the external auditory canal varied in the nonoperated ears (Kruskal-Wallis rank-sum test, 2880.9 ± 581.7 Hz, p = 0.02) but did not differ significantly in the operated ears (Kruskal-Wallis rank-sum test, 2464.4 ± 670.3 Hz, p = 0.75). In the finite-element model, the peak resonant frequencies along the depth of the external auditory canal varied in the normal ear and were homogeneous in the operated ear.

Conclusion: Radical mastoidectomy with meatoplasty altered the sound distribution in the external auditory canal. Our finite-element model successfully simulated the postoperative sound distribution in the external auditory canal and will facilitate development of wearable equipment for these patients.