Test-retest reliability of the Toy Discrimination Test with a masker of noise or babble in children with hearing impairment.

OBJECTIVE: The Toy Discrimination Test measures children's ability to discriminate spoken words. Previous assessments of reliability tested children with normal hearing or mild hearing impairment, and most studies used a version of the test without a masking sound. We assessed test-retest reliability for children with hearing impairment using maskers of broadband noise and two-talker babble. DESIGN: Stimuli were presented from a loudspeaker. The signal-to-noise ratio (SNR) was varied adaptively to estimate the speech-reception threshold (SRT) corresponding to 70.7% correct performance. Participants completed each masked condition twice. STUDY SAMPLE: Fifty-five children with permanent hearing impairment participated, aged 3.0 to 6.3 years. Thirty-four children used acoustic hearing aids; 21 children used cochlear implants. RESULTS: For the noise masker, the within-subject standard deviation of SRTs was 2.4 dB, and the correlation between first and second SRT was + 0.73. For the babble masker, corresponding values were 2.7 dB and + 0.60. Reliability was similar for children with hearing aids and children with cochlear implants. CONCLUSIONS: The results can inform the interpretation of scores from individual children. If a child completes a condition twice in different listening situations (e.g. aided and unaided), a difference between scores ≥ 7.5 dB would be statistically significant (p <.05).

Concurrent sound segregation based on inharmonicity and onset asynchrony.

To explore the neural processes underlying concurrent sound segregation, auditory evoked fields (AEFs) were measured using magnetoencephalography (MEG). To induce the segregation of two auditory objects we manipulated harmonicity and onset synchrony. Participants were presented with complex sounds with (i) all harmonics in-tune (ii) the third harmonic mistuned by 8% of its original value (iii) the onset of the third harmonic delayed by 160 ms compared to the other harmonics. During recording, participants listened to the sounds and performed an auditory localisation task whereas in another session they ignored the sounds and performed a visual localisation task. Active and passive listening was chosen to evaluate the contribution of attention on sound segregation. Both cues - inharmonicity and onset asynchrony - elicited sound segregation, as participants were more likely to report correctly on which side they heard the third harmonic when it was mistuned or delayed compared to being in-tune with all other harmonics. AEF activity associated with concurrent sound segregation was identified over both temporal lobes. We found an early deflection at approximately 75 ms (P75m) after sound onset, probably reflecting an automatic registration of the mistuned harmonic. Subsequent deflections, the object-related negativity (ORNm) and a later displacement (P230m) seem to be more general markers of concurrent sound segregation, as they were elicited by both mistuning and delaying the third harmonic. Results indicate that the ORNm reflects relatively automatic, bottom-up sound segregation processes, whereas the P230m is more sensitive to attention, especially with inharmonicity as the cue for concurrent sound segregation.

The cost and analysis of nonuse of cochlear implants.

OBJECTIVE: Analysis of the cost implications and reasons for nonuse of cochlear implants in an established cochlear implant unit. STUDY DESIGN: Clinical data were analyzed retrospectively to construct a table of cochlear implant use over time to identify nonuse and to suggest the reasons for this. SETTING: Yorkshire Cochlear Implant Service is a tertiary referral center. PATIENTS: Three hundred forty consecutively implanted patients from 1990 to 2005. MAIN OUTCOME MEASURES: Life table analysis showed that most children used their implant (p = 0.7 during 11 yr). However, 11 of 155 children and 2 of 185 adults became nonusers during the period of study. The 11 children stopped because of age at implant, educational placement, and family support. Two adults stopped because of psychological issues and inability to adapt to the signal. Surgical and implant costs have initial impact, with subsequent years' costs reflecting programming issues and maintenance. When considering nonuse, there are 2 effects: first, no more costs are incurred, and second, no more years of use are accumulated. Thus, nonuse reduces both costs and years. Costs of gaining a year of use as a function of time showed that there was little financial impact from the 11 children nonusers. As a ratio of "no nonuse" and observed "nonuse" in children, the ratio is 1.07 by 13 years of implantation (7%). The adult group was too few to analyze. CONCLUSION: The nonuse added 7% to the average cost. Retrospective audit identifies that patient selection by a multidisciplinary team is crucial to reducing nonuse.

Comparing utility scores before and after hearing-aid provision : results according to the EQ-5D, HUI3 and SF-6D.

Utility scores were estimated for 609 hearing-impaired adults who completed EQ-5D, Health Utilities Index Mark III (HUI3) and SF-6D survey instruments both before and after being provided with a hearing aid. Pre-intervention, the mean utility scores for EQ-5D (0.80) and SF-6D (0.78) were significantly higher than the mean HUI3 utility score (0.58). Post-intervention, the mean improvement in the HUI3 (0.06 change) was significantly higher than the mean improvement according to the EQ-5D (0.01 change) or SF-6D (0.01 change). The estimated cost effectiveness of hearing-aid provision is therefore likely to be dependent on which instrument is used to measure utility.

Strengths and Weaknesses of Procedures for Separating Simultaneous Voices.

Two signal-processing procedures for separating the continuously-voiced speech of competing talkers are described and evaluated. With competing sentences, each spoken on a monotone, the procedures improved the intelligibility of the target talker both for listeners with normal hearing and for listeners with moderate-to-severe hearing losses of cochlear origin. However, with intoned sentences, benefits were smaller for normal-hearing listeners and were inconsistent for impaired listeners. It is argued that smaller benefits arise with intoned sentences because harmonics of the two voices are blurred together during spectral analysis, limiting the extent to which spectral contrast can be recovered in the processed signal. This is particularly disadvantageous to impaired listeners who have reduced spectro-temporal resolution. This paper discusses other substantial problems to be overcome before the feasibility of the procedures as components of a speech-enhancement system for hearing-impaired listeners could be demonstrated.