Sound Pressure Distribution in the Ear after Radical Mastoidectomy with Meatoplasty

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.