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. 2023 Apr;280(4):1671-1676.
doi: 10.1007/s00405-022-07652-9. Epub 2022 Sep 17.

Habituation of changed acoustics properties after canal wall down mastoidectomy

M R Zwemstra  1 , P Brienesse  2 , M J F de Wolf  2 , E van Spronsen  2
Affiliations

Habituation of changed acoustics properties after canal wall down mastoidectomy

M R Zwemstra et al. Eur Arch Otorhinolaryngol. 2023 Apr.

Abstract

Purpose: Our objective is to evaluate the effect of habituation on the altered ear canal acoustics after canal wall down mastoidectomy.

Methods: A total of 11 participants with single sided dry cavities and normal contralateral ear canals with normal hearing thresholds were included in the study. Filtered sound fragments were created that simulate the different acoustic properties based on the participants Real Ear to Coupler Difference (RECD) of the cavity ear and the contralateral normal ear canal. These filtered sound fragments are presented to the cavity ear canal and the contralateral normal ear canal using inserts earphones. Participants performed a subjective quality assessment of the sound fragments using paired comparison with a seven-point scale (- 3 till + 3).

Results: Mean assessment of sound quality revealed the following results; naturalness of sounds of the cavity ear canal is 0.29 (± 1.41; ns) in favour of the filtered sound fragment of the normal ear canal. Mean assessment of sharpness of sounds in the cavity ear canal is 1.55 (± 1.21, p = 0.55) in favour of the filtered sound fragment of the normal ear canal. Overall preference in the cavity ear canal was in favour of the normal ear canal acoustics 0.72 (SD ± 1.54 p = 0.224).

Conclusions: Patients with cavity ear canals seem to habituate to their altered ear canal acoustics. Transforming the ear canal acoustics of the cavity ear to normal ear canal acoustics seem to sharpen the incoming sounds. Overall assessment of quality of sound of the normal ear canal acoustics is better than the cavity acoustics.

Keywords: Canal wall down; Ear canal acoustics; Hearing quality outcome.

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Conflict of interest statement

No financial disclosure or conflict of interest.

Figures

Fig. 1
Fig. 1
In this figure, a schematic representation of the real ear to coupler (RECD) measurement is displayed. The RECD accounts for the decibel difference across frequencies between sound pressure level (SPL) measured in the 2 cc coupler and the SPL measure in the participants individual ear, produced by the same transducer generating the same soundwave in decibels of a well-defined broadband sound stimulus. SPLM sound pressure level measure
Fig. 2
Fig. 2
These graphs illustrate how we created our sound filters. In the top chart, the RECD of the participants normal ear canal is displayed in green and the participants cavity ear canal in red. In the bottom chart the green line displays the difference in RECD between the cavity canal and the normal ear canal. In red, the difference in RECD is smoothed. The blue line is the frequency dependent filter we used to mimic the cavity canal acoustics in the normal ear of this participant. The inverse of this filter is used to mimic the frequency dependent filter to mimic normal ear canal acoustics in the cavity ear canal. These filters are created for each participant. RECD real ear to coupler difference
Fig. 3
Fig. 3
In this figure, the mean values for quality assessment of the sound fragments presented to the cavity ear canal and, respectively, the normal ear canal. They are presented as box-plots with 25th percentile and plotted on the horizontal axis for the assessment of naturalness, sharpness and overall quality (better) of sound. On the vertical axis the paired comparison outcome is displayed. Form 0 till + 3 represents an outcome in favour of the filtered sound fragments representing the normal ear canal acoustics. From 0 till − 3 represents an outcome in favour of the filtered sound fragment representing the cavity ear canal acoustics
See this image and copyright information in PMC

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