The development of linguistic stimuli for the Swedish Situated Phoneme test

Erik Witte,Susanne Köbler,Jonas Ekeroot

doi:10.1017/s0332586521000275

Abstract

AbstractThe speech perception ability of people with hearing loss can be efficiently measured using phonemic-level scoring. We aimed to develop linguistic stimuli suitable for a closed-set phonemic discrimination test in the Swedish language called the Situated Phoneme (SiP) test. The SiP test stimuli that we developed consisted of real monosyllabic words with minimal phonemic contrast, realised by phonetically similar phones. The lexical and sublexical factors of word frequency, phonological neighbourhood density, phonotactic probability, and orthographic transparency were similar between all contrasting words. Each test word was recorded five times by two different speakers, including one male and one female. The accuracy of the test-word recordings was evaluated by 28 normal-hearing subjects in a listening experiment with a silent background using a closed-set design. With a few exceptions, all test words could be correctly discriminated. We discuss the results in terms of content- and construct-validity implications for the Swedish SiP test.

Highlights

IntroductionUsing 100 TEST WORDS (TW) in each consecutive test (which is the highest number of items for which the authors mentioned above have calculated critical differences), a score of 70% in the first test requires the test taker to earn a score above 81% (or below 57%) on the second test for the difference to be considered statistically significant
2.1.1 Selecting candidate test phones To select contrasting TEST PHONES (TP) to include in the Situated Phoneme (SiP) test, we first calculated a measure of PHONETIC DISTANCE (PD) between all Swedish phones that occur as contrasting phonemes in Swedish monosyllabic words
The sets of contrasting phones manifested in the Swedish MINIMALVARIATION GROUPS (MVGs) in Table 2 embody most of the 31 sets of candidate TPs identified in Section 2.1.1

Summary

Introduction

Using 100 TWs in each consecutive test (which is the highest number of items for which the authors mentioned above have calculated critical differences), a score of 70% in the first test requires the test taker to earn a score above 81% (or below 57%) on the second test for the difference to be considered statistically significant In essence, this means that the benefit provided by the specific hearing intervention under investigation needs to make an additional 12 words (out of 100) perceivable by the subject for the improvement to be statistically significant. If each phoneme within a word list is considered an independent test trial, the number of trials within each list will be considerably higher, which in turn will result in narrower critical difference limits (Olsen et al 1997) This procedure violates two assumptions that need to be fulfilled for the sampling distribution of speech-audiometry scores to be approximated by binomial distributions. The success probability of each phoneme in a PB50 word list will be very different, and difficult to predict

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Conclusion