Phoneme and Word Scoring in Speech-in-Noise Audiometry

Abstract

Purpose: Understanding speech in background noise is difficult for many individuals; however, time constraints have limited its inclusion in the clinical audiology assessment battery. Phoneme scoring of words has been suggested as a method of reducing test time and variability. The purposes of this study were to establish a phoneme scoring rubric and use it in testing phoneme and word perception in noise in older individuals and individuals with hearing impairment.

Method: Words were presented to 3 participant groups at 80 dB in speech-shaped noise at 7 signal-to-noise ratios (-10 to 35 dB). Responses were scored for words and phonemes correct.

Results: It was not surprising to find that phoneme scores were up to about 30% better than word scores. Word scoring resulted in larger hearing loss effect sizes than phoneme scoring, whereas scoring method did not significantly modify age effect sizes. There were significant effects of hearing loss and some limited effects of age; age effect sizes of about 3 dB and hearing loss effect sizes of more than 10 dB were found.

Conclusion: Hearing loss is the major factor affecting word and phoneme recognition with a subtle contribution of age. Phoneme scoring may provide several advantages over word scoring. A set of recommended phoneme scoring guidelines is provided.

Figure 1.

Mean thresholds for Group A (blue line), Group B (green line), and Group C (red line). Thresholds are displayed for the right ear only. To account for high-frequency threshold differences between Group A and Group B, all stimuli were low-pass filtered at 4000 Hz (depicted by gray shading). Error bars represent the standard errors of the mean.

Figure 2.

Psychometric functions (above) and mean SNR50 and SNR70 performance estimates (below) displaying word (left column) and phoneme (right column) results. Group differences are displayed as the parameter within each subplot and are generally much larger as a function of hearing impairment (Group B vs. Group C) than they are for age (Group A vs. Group B). Differences between Groups A and B are approximately 3 dB, and differences between Groups B and C are usually larger than 10 dB. All error bars represent the standard errors of the mean.

Figure 3.

Word and phoneme psychometric functions (left) and word–phoneme correlations (right) for all three groups for signals presented at 80 dB SPL (error bars represent standard errors of the mean). In general, the overall shape of the function is similar across scoring methods with phoneme scores being 10%–20% better than word scores. Word–phoneme correlations reveal strong relationships between scoring methods.