Voice fundamental frequency differences and speech recognition with noise and speech maskers in cochlear implant recipients

Cochlear implant (CI) recipients are limited in their perception of voice cues, such as the fundamental frequency (F0). This has important consequences for speech recognition when several talkers speak simultaneously. This examination considered the comparison of clear speech and noise-vocoded sentences as maskers. For the speech maskers it could be shown that good CI performers are able to benefit from F0 differences between target and masker. This was due to the fact that a F0 difference of 80 Hz significantly reduced target-masker confusions, an effect that was slightly more pronounced in bimodal than in bilateral users.

Characteristics and international comparability of the Finnish matrix sentence test in cochlear implant recipients

OBJECTIVES

The first Finnish sentence-based speech test in noise--the Finnish matrix sentence test--was recently developed. The aim of this study was to determine the characteristics of the new test with respect to test-retest reliability, speech recognition curve, and international comparability in Finnish cochlear implant (CI) recipients.

DESIGN

The speech reception thresholds (SRT) were measured by means of an adaptive test procedure and compared with the results of the traditional Finnish word test. Additional measurements for concurrent slope and SRT estimation were conducted to determine the speech recognition curve and to check the test-retest reliability.

STUDY SAMPLE

The measurements were performed on 78 Finnish CI recipients. In a subset of 25 patients, additional measurements for test-retest reliability and slope determination were performed.

RESULTS

The mean SRT was -3.5 ± 1.7 dB SNR, with only a weak correlation with the Finnish word test. Test-retest reliability was within ± 1 dB and the mean slope of the speech recognition curve was 14.6 ± 3.6 %/dB. The rehabilitation results were similar to the results published for the German matrix test.

CONCLUSIONS

The Finnish matrix test was found to be suitable and efficient in CI recipients with similar characteristics as the German matrix test.

Development and validation of a Chinese music quality rating test

OBJECTIVE

The present study aims to develop and validate a Chinese music quality rating test (MQRT).

DESIGN

In Experiment 1, 22 music pieces were initially selected and paired as a 'familiar music piece' and 'unfamiliar music piece' based on familiarities amongst the general public in the categories of classical music (6), Chinese folk music (8), and pop music (8). Following the selection criteria, one pair of music pieces from each music category was selected and used for the MQRT in Experiment 2. In Experiment 2, the MQRT was validated using these music pieces in the categories 'Pleasantness', 'Naturalness', 'Fullness', 'Roughness', and 'Sharpness'.

STUDY SAMPLE

Seventy-two adult participants and 30 normal-hearing listeners were recruited in Experiments 1 and 2, respectively.

RESULTS

Significant differences between the familiar and unfamiliar music pieces were found in respect of pleasantness rating for folk and pop music pieces as well as in sharpness rating for pop music pieces. The comparison of music category effect on MQRT found significant differences in pleasantness, fullness, and sharpness ratings.

CONCLUSION

The Chinese MQRT developed in the present study is an effective tool for assessing music quality.

Natural history of contralateral residual hearing in unilateral cochlear implant users - long-term findings

CONCLUSION

The long-term stability of low-frequency residual hearing found in a significant number of bilateral-bimodal users (cochlear implant (CI) in one ear and a hearing aid (HA) on the other ear; CI/HA) with severe-to-profound or profound hearing loss in the non-implanted ear justifies bilateral-bimodal fitting efforts in this group. Since low-frequency residual hearing tends to deteriorate in some of these CI/HA users, periodic evaluation, which includes pure-tone thresholds and speech perception tests, is mandatory for determining the point in time at which CI/HA hearing is no longer effective, and the patient should accordingly be considered as a candidate for contralateral cochlear implantation.

OBJECTIVE

To determine, in bilateral-bimodal (CI/HA) users with severe-to-profound or profound hearing loss in the non-implanted ear, the rate of residual hearing deterioration in the non-implanted ear after cochlear implantation.

METHODS

Pure-tone aided and unaided thresholds in the non-implanted ears of 39 CI/HA users at 0.25-4.0 kHz were recorded prospectively up to 6 years after implantation.

RESULTS

Group mean threshold values in the non-implanted ears remained stable over 3, 4, 5 and 6 years post-implantation, except for significant deterioration at 4.0 kHz of both unaided (4.2, 5.2, 9.0 and 8.2 dB, respectively) and aided thresholds (8.1, 4.6, 6.1 and 8.3 dB, respectively).

Voice gender differences and separation of simultaneous talkers in cochlear implant users with residual hearing

Perception of a target voice in the presence of a competing talker, of same or different gender as the target, was investigated in cochlear implant users, in implant-alone and bimodal (acoustic hearing in the non-implanted ear) conditions. Recordings of two male and two female talkers acted as targets and maskers, to investigate whether bimodal benefit increased for different compared to same gender target/maskers due to increased ability to perceive and utilize fundamental frequency and spectral-shape differences. In both listening conditions participants showed benefit of target/masker gender difference. There was an overall bimodal benefit, which was independent of target/masker gender difference.

The relative phonetic contributions of a cochlear implant and residual acoustic hearing to bimodal speech perception

The addition of low-passed (LP) speech or even a tone following the fundamental frequency (F0) of speech has been shown to benefit speech recognition for cochlear implant (CI) users with residual acoustic hearing. The mechanisms underlying this benefit are still unclear. In this study, eight bimodal subjects (CI users with acoustic hearing in the non-implanted ear) and eight simulated bimodal subjects (using vocoded and LP speech) were tested on vowel and consonant recognition to determine the relative contributions of acoustic and phonetic cues, including F0, to the bimodal benefit. Several listening conditions were tested (CI/Vocoder, LP, T(F0-env), CI/Vocoder + LP, CI/Vocoder + T(F0-env)). Compared with CI/Vocoder performance, LP significantly enhanced both consonant and vowel perception, whereas a tone following the F0 contour of target speech and modulated with an amplitude envelope of the maximum frequency of the F0 contour (T(F0-env)) enhanced only consonant perception. Information transfer analysis revealed a dual mechanism in the bimodal benefit: The tone representing F0 provided voicing and manner information, whereas LP provided additional manner, place, and vowel formant information. The data in actual bimodal subjects also showed that the degree of the bimodal benefit depended on the cutoff and slope of residual acoustic hearing.

Contribution of a contralateral hearing aid to perception of consonant voicing, intonation, and emotional state in adult cochlear implantees

Binaural hearing in cochlear implant (CI) users can be achieved either by bilateral implantation or bimodally with a contralateral hearing aid (HA). Binaural-bimodal hearing has the advantage of complementing the high-frequency electric information from the CI by low-frequency acoustic information from the HA. We examined the contribution of a contralateral HA in 25 adult implantees to their perception of fundamental frequency-cued speech characteristics (initial consonant voicing, intonation, and emotions). Testing with CI alone, HA alone, and bimodal hearing showed that all three characteristics were best perceived under the bimodal condition. Significant differences were recorded between bimodal and HA conditions in the initial voicing test, between bimodal and CI conditions in the intonation test, and between both bimodal and CI conditions and between bimodal and HA conditions in the emotion-in-speech test. These findings confirmed that such binaural-bimodal hearing enhances perception of these speech characteristics and suggest that implantees with residual hearing in the contralateral ear may benefit from a HA in that ear.