Development and validation of a sentence-in-noise test for signal-to-noise ratio loss in adult normal-hearing and hearing-impaired listeners in South Africa

Abstract

Background: Difficulties understanding speech in noise are common in adults with hearing impairment. Yet, validated sentence-based speech-in-noise measures remain limited in South African clinical practice.
Objectives: To validate two language-specific South African sentence-in-noise tests, the South African Sentence-in-Noise (SASIN) test and Suid-Afrikaanse Sin-in-Geraas (SASIG) test, by examining inter-list comparability and determining the signal-to-noise ratio (SNR) required for 50% correct sentence recognition (SNR-50).
Method: A quantitative, retrospective validation study used routinely collected clinical data from adult first-language speakers of South African English (SASIN; n = 36) or Afrikaans (SASIG; n = 51) across multiple audiology sites. Participants completed five sentence lists in four-talker babble using fixed 5 dB SNR steps. Keyword scores were analysed for inter-list comparability and for deriving SNR-50 and SNR-loss values.
Results: Friedman analyses indicated significant overall list effects for both tests. Bonferroni-adjusted pairwise comparisons indicated that only selected comparisons, primarily involving List 1, reached statistical significance, whereas most pairwise comparisons were not statistically significant. Overall, the findings supported broad inter-list comparability.
Conclusion: The SASIN and SASIG tests demonstrated acceptable psychometric properties as language-specific sentence-in-noise measures for South African English- and Afrikaans-speaking adults, supporting their clinical use.
Contribution: This study provides validated first-language sentence-in-noise tools and test-specific SNR-50 and SNR-loss metrics for adult audiological assessment in South Africa.