Acoustic analysis of the voiced-voiceless distinction in Dutch tracheoesophageal speech.

PURPOSE: Confusions between voiced and voiceless plosives and voiced and voiceless fricatives are common in Dutch tracheoesophageal (TE) speech. This study investigates (a) which acoustic measures are found to convey a correct voicing contrast in TE speech and (b) whether different measures are found in TE speech than in normal laryngeal (NL) speech. The main focus was on plosives. METHOD: Nine TE and 5 NL speakers were included in this study. Fourteen acoustic measures were selected and analyzed. Comparisons were made between voiced and voiceless for the groups separately and between TE and NL speakers. Conditional inference trees were used to establish the most important distinguishing cue. RESULTS: TE speakers do not differ significantly from NL speakers, except for pitch-related measures. For plosives, all measures distinguished between voiced and voiceless for both speaker groups. The main distinguishing measure for the plosives was relative phonation time in the closure. CONCLUSIONS: TE and NL speakers differ less in the way the voiced-voiceless distinction is conveyed than expected. Further research is needed to show whether the main acoustic cue is also perceptually most relevant.

Comparing deaf and hearing Dutch infants: changes in the vowel space in the first 2 years.

The influence of the mother tongue on vowel productions in infancy is different for deaf and hearing babies. Audio material of five hearing and five deaf infants acquiring Dutch was collected monthly from month 5-18, and at 24 months. Fifty unlabelled utterances were digitized for each recording. This study focused on developmental paths in vowel productions. The applied automated band filtering analysis is F0-independent and results in a spectral envelope, sampled in a 40-dimensional space. Via a Principal Component Analysis (PCA, data reduction), a vowel space for normally hearing 2-year-olds was constructed, enabling the projection of the individual developmental data of the infants in a two-dimensional reference plane. Comparison of the results for the hearing and the deaf infants over 2 years indicates individual as well as group differences. The amount of hearing loss as well as the communication styles seem to be important factors in explaining differences between the infant categories.

Acoustic signal typing for evaluation of voice quality in tracheoesophageal speech.

SUMMARY: Because of the aperiodicity of many tracheoesophageal voices, acoustic analysis of the tracheoesophageal voice is less straightforward than that of the normal voice. This study presents the development and testing of an acoustic signal typing system based on visual inspection of a narrow-band spectrogram that can be used by researchers for classification of voice quality in tracheoesophageal speech. In addition to this classification system, a selection of acoustic measures [median fundamental frequency, standard deviation of fundamental frequency, jitter, percentage of voiced (%Voiced), harmonics-to-noise ratio (HNR), glottal-to-noise excitation (GNE) ratio, and band energy difference (BED)] was computed to provide more insight into the acoustic components of tracheoesophageal voice quality. For clinical relevance, relationships between the acoustic signal types and an overall judgment of the voice were investigated as well. Results showed that the four acoustic signal types form a good basis for performing more acoustic analyses and give a good impression of the overall quality of the voice.

Anatomical and functional correlates of voice quality in tracheoesophageal speech.

The purpose of the current study was to assess the anatomic and functional correlates of voice quality in tracheoesophageal speech, with dynamic imaging studies of the neoglottis. Videofluoroscopy (providing a lateral view), digital high-speed endoscopy (providing a "birds-eye" view), and their relationships with perceptual evaluations of voice quality were investigated. Several significant relationships were found. Imaging with videofluoroscopy revealed that the following anatomic and functional parameters (established during phonation) are related to voice quality: presence of a neoglottic bar, regurgitation of barium, tonicity of the neoglottis, and minimal neoglottic distance. Furthermore, the index of the increase of the maximal subneoglottic distance from rest to phonation also showed a significant relationship with voice quality. Imaging with digital high-speed endoscopy revealed features relevant to voice quality, including amount of saliva, visibility of the origin of the neoglottis, shape of the neoglottis, and regularity of the vibration. Knowledge of the anatomic and functional correlates of tracheoesophageal voice quality provides prerequisite information for future (phono-) surgical and/or clinical improvements to the voice quality of postlaryngectomy (prosthetic) voice production.

Perceptual evaluation of tracheoesophageal speech by naive and experienced judges through the use of semantic differential scales.

The present study was conducted to investigate voice quality in tracheoesophageal speech by means of perceptual evaluations and to develop a clinically useful subset of perceptual scales sufficient for these perceptual evaluations. The perceptual ratings were obtained from both naive and trained raters (speech-language pathologists [SLPs]) after listening to a read-aloud text. The perceptual evaluations were performed by means of 19 semantic bipolar 7-point scales for the naive raters and 20 semantic bipolar 7-point scales for the trained raters. The trained raters were also asked to judge the overall voice quality as good, reasonable, or poor. Both naive listeners and trained SLPs were able to perform reliable perceptual judgments. Naive raters judged the tracheoesophageal voice as more deviant than the trained raters did. Naive raters made judgments based on 2 underlying perceptual dimensions (voice quality and pitch), whereas the trained raters made judgments based on 4 underlying perceptual dimensions (voice quality, tonicity, pitch, and tempo). These perceptual dimensions were further subdivided into a subset of 4 perceptual scales for the naive raters and a subset of 8 perceptual scales for the trained raters. This appeared to provide a sufficient coverage of the underlying perceptual dimensions used by the listeners.