Speech discrimination impairments as a marker of disease severity in multiple sclerosis

BACKGROUND

Multiple Sclerosis (MS) pathology is likely to disrupt central auditory pathways, thereby affecting an individual's ability to discriminate speech from noise. Despite the importance of speech discrimination in daily communication, it's characterization in the context of MS remains limited. This cross-sectional study evaluated speech discrimination in MS under "real world" conditions where sentences were presented in ecologically valid multi-talker speech or broadband noise at several signal-to-noise ratios (SNRs).

METHODS

Pre-recorded Bamford-Kowal-Bench sentences were presented at five signal-to-noise ratios (SNR) in one of two background noises: speech-weighted noise and eight-talker babble. All auditory stimuli were presented via headphones to control (n = 38) and MS listeners with mild (n = 20), moderate (n = 16) and advanced (n = 10) disability. Disability was quantified by the Kurtzke Expanded Disability Status Scale (EDSS) and scored by a neurologist. All participants passed a routine audiometric examination.

RESULTS

Despite normal hearing, MS psychometric discrimination curves which model the relationship between signal-to-noise ratio (SNR) and sentence discrimination accuracy in speech-weighted noise and babble did not change in slope (sentences/dB) but shifted to higher SNRs (dB) compared to controls. The magnitude of the shift in the curve systematically increased with greater disability. Furthermore, mixed-effects models identified EDSS score as the most significant predictor of speech discrimination in noise (odds ratio = 0.81; p < 0.001). Neither age, sex, disease phenotype or disease duration were significantly associated with speech discrimination performance in noise. Only MS listeners with advanced disability self-reported audio-attentional difficulty in a questionnaire designed to reflect auditory processing behaviours in daily life.

CONCLUSION

Speech discrimination performance worsened systematically with greater disability, independent of age, sex, education, disease duration or disease phenotype. These results identify novel auditory processing deficits in MS and highlight that speech discrimination tasks may provide a viable non-invasive and sensitive means for disease monitoring in MS.

Effect of wireless remote microphone application on speech discrimination in noise in children with cochlear implants

OBJECTIVES

Although cochlear implantation has significantly contributed to the speech perception of cochlear implant (CI) users, these individuals still have significant difficulty in understanding speech, especially in noisy environments and keeping track of the target speaker in the presence of speech sounds of others. This study was aimed to evaluate the effect of wireless Remote Microphones (RM) on speech discrimination scores in noise in child CI users.

MATERIALS AND METHODS

Twenty children with unilateral cochlear implantation were enrolled in this study with mean ± SD age of 5.8 ± 0.83 years who have undergone CI for at least one year. Speech discrimination scores in noise were assessed using the Words-in-Noise (WIN) test at a constant signal-to-noise ratio (SNR) of 0 dB, in the presence and absence of a wireless RM. Three loudspeakers were placed at a distance of 1 m in front of the child to present the speech and babble noise. The wireless microphone was placed on a base with a height equivalent to the height of the middle speech loudspeaker at a distance of 30 cm from it.

FINDINGS

The mean speech discrimination score in noise in the absence of wireless RM in all children was obtained 34% (6.8 words out of 20 words), with minimum and maximum of 15% and 50% words. Findings revealed the mean speech discrimination score in noise in the presence of wireless RMs is equivalent to 65% (13 words out of 20 words), with the minimum and maximum scores of 35% and 95%, respectively. The result showed that speech discrimination scores in noise improved in the presence of wireless RM.

CONCLUSION

The significant improvement was observed in speech discrimination in noise in all cochlear implanted children when the wireless RM was used, as compared to the absence of a wireless RM, which suggests the usefulness of this hearing aid accessory in CI users.