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M C Langereis

Publications and source records attributed to M C Langereis.

7 recordsLinked to original sources
PubMed1997

Effect of cochlear implantation on nasality in post-lingually deafened adults.

The present study addresses the effect of cochlear implantation on nasality in 21 post-lingually deafened Dutch subjects. All subjects received the Nucleus 22 implant (MSP version). Speech recordings were made pre-implantation and 3 and 12 months post-implantation with the implant switched on and off. Nasality measurements were performed on a standard text and on two sentences without nasal phonemes. The results show that post-lingual deafness in individuals can result in a deviant degree of nasality in speech production. However, the nasalance value of 86% of the subjects of our study fell within the normative range defined as the mean +/- 2 standard deviations of the normal population. After implantation we found no statistically significant effect of implant use. However, individual nasality values outside the normative range may improve. Furthermore, 12 months post-implantation we found a significant decrease in the variability of the nasalance values obtained for two sentences without nasal phonemes.

Adult↗
PubMedDate not supplied

Changes in vowel quality in post-lingually deafened cochlear implant users.

The present study addresses the effect of cochlear implantation on vowel production of 20 post-lingually deafened Dutch subjects. All subjects received the Nucleus 22 implant (3 WSP and 17 MSP processors). Speech recordings were made pre-implantation and three and twelve months post-implantation with the implant switched on and off. The first and second formant frequencies were measured for eleven Dutch vowels (monophthongs only) in an h-vowel-t context. Twelve months post-implantation, the results showed an increase in the ranges of the first and second formant frequency covered by the respective vowels when the implant was switched on. The increase in the formant frequency range was most marked for some subjects with a relatively small formant range pre-implantation. Also, at 12 months post-implantation with the implant switched on we found a significant shift of the first and second formant frequency towards the normative values. Moreover, at this time the results showed significantly increased clustering of the respective vowels, suggesting an improvement in the ability to produce phonological contrasts between vowels. Clustering is defined as the ratio of the between-vowel variance of the first and second formant frequency and the within-vowel variance of three tokens of the same vowel.

Adult↗
PubMedDate not supplied

Effect of cochlear implantation on voice fundamental frequency in post-lingually deafened adults.

The present study addresses the effect of cochlear implantation on the voice fundamental frequency at which 20 post-lingually deafened Dutch subjects utter speech materials. All subjects received the Nucleus 22 cochlear implant (3 WSP and 17 MSP processors). Speech recordings were made pre-implantation and three and twelve months post-implantation with the implant switched on and off. The fundamental frequency (f0) was sampled while reading a text. The pre-implantation results show that in some subjects, f0 was too high compared with the range in f0 of normally-hearing subjects. Post-implantation, with the implant switched on, we found that the abnormally high f0 values pre-implantation changed toward the normative values. In addition, post-implantation we found that the range over which f0 varied within a subject while reading the text, the f0 sway, decreased for most subjects who, pre-implantation, had their f0 sway outside the normative ranges, the normative range being defined as the interval between the mean plus/minus one standard deviation of the f0 sway found for normally-hearing subjects. Voice fundamental frequency of post-lingually deafened adults is characterized by large interindividual variability in the pre-implantation f0 values. This large interindividual variability is found also in the effect of cochlear implantation on f0.

Adult↗
PubMedDate not supplied

Predictors of cochlear implant performance.

Open set speech understanding with cochlear implants, without speechreading, is nowadays a common finding. However, there is a large variation in speech understanding between cochlear implant users. We tried to find pre-operative parameters which predicted the post-operative results. Thirty-seven adult post-lingually deafened Nucleus cochlear implant users with a mean age of 46 years (range 16 68) and a mean duration of deafness of 15 years (range 1.5-47) were studied. Pre-operatively, we performed pure-tone audiometry, round window and ear canal electrical stimulation, psychological tests and imaging. Additionally, we measured pre-operatively speech understanding in the auditory, the visual and the audiovisual conditions with several tests which were also administered after 6 and 12 months' implant experience. Correlation analysis between the pre-operative variables and the post-operative factors showed that duration of deafness and residual hearing are the most important predictors. The temporal difference limen in pre-operative round window electrical stimulation is a secondary predictor.

Adolescent↗
PubMedDate not supplied

Intelligibility of vowels produced by post-lingually deafened cochlear implant users.

The present study addresses the effect of cochlear implantation on the intelligibility of vowels produced by 20 post-lingually deafened Dutch subjects. All subjects received the Nucleus-22 cochlear implant (3 WSP and 17 MSP processors). Speech recordings were made pre-implantation and three and twelve months post-implantation with the implant switched on and off. Vowel intelligibility (monophthongs only) was determined using a panel of listeners. For all implanted subjects intelligibility was measured in a noisy background. For seven poorly speaking subjects it was also measured in a quiet background. After implantation with the Nucleus-22 device the results showed that vowel intelligibility, measured for all subjects in a noisy background, increased for most of them (about 15), while it increased for about half the number of poorly speaking subjects measured in a quiet background. Twelve months after implantation vowel intelligibility, measured for all subjects in noise, appeared to be based on first and second formant information. This was also found for the subgroup of seven subjects performing poorly pre-implantation when analysed separately. However, vowel intelligibility for this subgroup, when measured in a quiet background, was based also on vowel duration. The differences between the overall result in noise and the results of the subgroup in quiet should be attributed mainly to the noise and not to aspects of poor speech production in the subgroup. In addition, this study addresses the relationship between the intelligibility scores and objective measurements of vowel quality performed in a previous study. The results showed that the vowel intelligibility scores are mainly determined by the position of the second formant frequencies.

Adult↗