Pressure-Less Acoustic Immittance-Derived Middle Ear Resonance Frequency: Repeatability and Comparison with Multifrequency Tympanometry.

Background/

Objectives

This study evaluated the intra-session repeatability, reliability, and clinical consistency of resonance frequency derived from pressure-less acoustic immittance (PLAI), and compared the results with those obtained using conventional multifrequency tympanometry under identical clinical conditions.

Methods

In this pilot methodological comparison study, resonance frequency (RF) measurements were obtained in 15 subjects (30 ears) using multifrequency tympanometry (MFT) and pressure-less acoustic immittance (PLAI). Three consecutive measurements were performed for each ear using both methods. Agreement between methods was evaluated using Bland-Altman analysis. Within-method repeatability was assessed using range, coefficient of variation, repeatability coefficient, and intraclass correlation coefficients.

Results

PLAI demonstrated lower intra-session variability than MFT. The mean within-series SD was 96.6 Hz for MFT and 10.5 Hz for PLAI. The coefficient of variation was 9.3% for MFT and 3.2% for PLAI, while intraclass correlation coefficients were 0.60 and 0.83, respectively. The repeatability coefficient was ±367 Hz for MFT and ±47 Hz for PLAI. Bland-Altman analysis revealed a systematic difference between the two methods, with a mean bias of 580.7 Hz and 95% limits of agreement between 247.5 Hz and 913.9 Hz, indicating that the two methods are not interchangeable.

Conclusions

PLAI demonstrated higher repeatability than MFT. Its lower variability may support a more consistent clinical interpretation; PLAI-derived RF may therefore represent a stable method-specific parameter for middle ear assessment. However, RF values should be interpreted within method-specific frameworks.