Difference in SII provided by initial fit and NAL-NL2 and its relation to self-reported hearing aid outcomes

Sreeram K Narayanan; Palle Rye; Sabina Storbjerg Houmøller; Anne Wolff; Dan Dupont Hougaard; Michael Gaihede; Jesper Hvass Schmidt; Dorte Hammershøi

doi:10.1080/14992027.2023.2291633

Difference in SII provided by initial fit and NAL-NL2 and its relation to self-reported hearing aid outcomes

Int J Audiol. 2023 Dec 19:1-8. doi: 10.1080/14992027.2023.2291633. Online ahead of print.

Authors

Sreeram K Narayanan¹, Palle Rye¹, Sabina Storbjerg Houmøller^{2

3}, Anne Wolff⁴, Dan Dupont Hougaard^{4

5}, Michael Gaihede^{4

5}, Jesper Hvass Schmidt^{2

3}, Dorte Hammershøi¹

Affiliations

¹ Department of Electronic Systems, Section for AI and Sound, Aalborg University, Aalborg, Denmark.
² Research Unit for ORL - Head & Neck Surgery and Audiology, Odense University Hospital & University of Southern Denmark, Odense, Denmark.
³ OPEN, Odense Patient data Explorative Network, Odense University Hospital, Odense, Denmark.
⁴ Department of Otolaryngology, Head & Neck Surgery and Audiology, Aalborg University Hospital, Aalborg, Denmark.
⁵ Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.

PMID: 38112025
DOI: 10.1080/14992027.2023.2291633

Abstract

Objective: The speech intelligibility index (SII) is used to quantify the audibility of the speech. This study examined the relationship between self-reported hearing aid (HA) outcomes and the difference in aided SII (SII_A) calculated from the initial fit (IF) gain and that prescribed as per the second generation of National Acoustic Laboratory Non-Linear (NAL-NL2).

Design: A prospective observational study.

Study sample: The study included 718 first-time and 253 experienced HA users. All users had a valid real-ear measurement (REM) at three input levels (55, 65 and 80 dB SPL).

Results: The gain provided by IF was lower than NAL-NL2 at 55 and 65 dB SPL. IF gain exhibited reduced compression than NAL-NL2 as input levels increased from 55 to 80 dB SPL. On average, the SII_A provided by IF was significantly lower than that for NAL-NL2 at all input levels. The difference in SII_A between IF and NAL-NL2 at 80 dB SPL input level with 0 dB signal-to-noise ratio (SNR) turned out to be a predictor for self-reported outcome for first-time HA users.

Conclusion: The study suggests that an SIIA close to that provided by NAL-NL2 at high input levels would be preferred to obtain a better self-reported outcome. .

Keywords: Gain prescription; hearing aids; self-reported outcome; speech intelligibility index.