Comparison of three types of French speech-in-noise tests: a multi-center study.

OBJECTIVE: To compare results on the everyday sentence test 'FIST', the new closed-set sentence test 'FrMatrix', and the digit triplet screening test 'FrDigit3'. DESIGN: First, the FrMatrix was developed and normative values were obtained. Subsequently, speech reception thresholds (SRTs) for the three types of tests were gathered at four study centers representing different geographic regions in Belgium and France. STUDY SAMPLE: Fifty-seven normal-hearing listeners took part in the normative study of the FrMatrix, and 118 subjects, with a wide range of hearing thresholds, participated in the comparative study. RESULTS: Homogenizing the individual words of the FrMatrix with regard to their intelligibility resulted in a reference SRT of -6.0 (±0.6) dB SNR and slope at the SRT of 14.0 %/dB. The within-subject variability was only 0.4 dB. Comparison of the three tests showed high correlations between the SRTs mutually (>0.81). The FrMatrix had the highest discriminative power, both in stationary and in fluctuating noise. For all three tests, differences across the participating study centers were small and not significant. CONCLUSIONS: The FIST, the FrMatrix, and the FrDigit3 provide similar results and reliably evaluate speech recognition performance in noise both in normal-hearing and hearing-impaired listeners.

The French digit triplet test: a hearing screening tool for speech intelligibility in noise.

A French speech intelligibility screening test in noise that applies digit triplets as stimuli has been developed and evaluated for both telephone and broadband headphone use. After optimizing the speech material based on the intelligibility of the individual digits, norms for normal-hearing subjects were established. speech reception thresholds (SRTs) of -6.4 +/- 0.4 and -10.5 +/- 0.3 dB SNR, and slopes of 17.1 and 27.1 %/dB were obtained for telephone and broadband headphone presentation, respectively. The French digit triplet test by telephone was then implemented as an automatic self-screening test by home telephone, and further evaluated in normal-hearing and hearing-impaired listeners. A test-retest variability of 0.7 dB was found and the correlation between SRT and pure-tone average (PTA(0.5,1,2,4)) was 0.77. One month after launching the test, 20,000 calls were registered. It can be concluded that both versions of the newly developed test have steep slopes and small SRT differences across normal-hearing listeners. The screening test by telephone is highly reliable and proves to fulfill the need for an easily accessible and objective hearing screening.

Recording and classification of the acoustic environment of hearing aid users.

This article investigates the different acoustic signals that hearing aid users are exposed to in their everyday environment. Binaural microphone signals from recording positions close to the microphone locations of behind-the-ear hearing aids were recorded by 20 hearing aid users during daily life. The recorded signals were acoustically analyzed with regard to narrowband short-term level distributions. The subjects also performed subjective assessments of their own recordings in the laboratory using several questions from the Glasgow Hearing Aid Benefit Profile (GHABP) questionnaire. Both the questionnaire and the acoustic analysis data show that the importance, problems, and hearing aid benefit as well as the acoustic characteristics of the individual situations vary a lot across subjects. Therefore, in addition to a nonlinear hearing aid fitting, further signal classification and signal/situation-adaptive features are highly desirable inside modern hearing aids. These should be compatible with the variability of the individual sound environments of hearing-impaired listeners.

The role of silent intervals for sentence intelligibility in fluctuating noise in hearing-impaired listeners.

Fluctuating interfering noises are highly suitable for speech audiometry because of the large inter-individual variability in intelligibility results. This study explores the maximum duration of silent intervals in the masker as an important factor underlying sentence intelligibility in fluctuating noise. Three versions of speech-simulating fluctuating interfering noises based on the icra noises (Dreschler et al, 2001) were explored: The original noise which simulates one interfering speaker and contains pause durations up to two seconds, as well as two modified versions with pause durations limited to 250 ms and 62.5 ms, respectively. In addition, a stationary speech-shaped noise was used. Test-retest reliability as well as speech reception threshold (SRT) and speech intelligibility function slope were determined with hearing-impaired subjects. All fluctuating noises differentiated very well between subjects. Partial rank correlation analysis showed that SRTs in fluctuating noise with longest maximum pause durations mostly depended on SRTs in quiet. SRTs in fluctuating noises with smaller maximum pause durations correlated both with SRTs in quiet and in stationary noise.

Sentence intelligibility in noise for listeners with normal hearing and hearing impairment: influence of measurement procedure and masking parameters.

Speech intelligibility measurements strongly depend on several procedural parameters. In order to obtain comparable results from different test procedures, these parameters must be investigated as to which should be standardized and which could be set freely. This study investigates the influence of noise level, noise type, and presentation mode on speech reception thresholds (SRTs), and intelligibility function slopes in noise for normal-hearing and hearing-impaired subjects. The noise presentation level had no significant influence on either SRTs or slope values, provided that the presentation level exceeded hearing threshold. Two stationary, speech-shaped noises produced identical results. Speech-simulating fluctuating noise yielded about 14 dB lower SRTs for normal-hearing subjects and about 10 dB lower SRTs for 20% of the heating-impaired subjects. Of the hearing-impaired subjects, 30% did not benefit from the modulations and showed similar SRTs as for stationary noise. Using continuous noise yielded lower SRTs compared to gated noise. However, the difference between the results in continuous and gated noise was not significant for the hearing-impaired subjects. A presentation level of 65 dB SPL (normal-hearing subjects) or 80 dB SPL (hearing-impaired subjects) and an interfering noise with a spectrum similar to the mean long-term average speech spectrum (LTASS) is suggested for comparable adaptive measurement procedures. A fluctuating, speech-shaped noise is recommended to differentiate between subjects.