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D J Povel

Publications and source records attributed to D J Povel.

13 recordsLinked to original sources
PubMed1990

Predicting voice quality of deaf speakers on the basis of glottal characteristics.

Twenty profoundly deaf and 5 normal-hearing subjects produced 225 sustained vowels/a, i, u/at different pitch levels and 75 phonetically balanced sentences, while vocal fold vibration was recorded through an electrolaryngograph (ELG). The utterances recorded on audio tape were judged by 10 experienced listeners on general voice quality, breathiness, hoarseness, and laryngeal strain on a 5-point scale. Seven parameters describing time-domain characteristics of the ELG-signal were extracted online by a special purpose computer system. Measurements were made over 500 consecutive vibratory cycles (10-cycle window), yielding a mean and standard deviation for each parameter per utterance. All data were submitted to analysis of variance and multiple regression analyses. Multiple correlations between glottal parameters and judged voice deviations varied between .46 and .70 indicating that overall prediction cannot reliably be based on these parameters, although severe cases of deaf voice deviations may be detectable.

Adolescent↗
PubMed1986

A computer-controlled vowel corrector for the hearing impaired.

The Vowel Corrector is a visual aid to be used in speech training of the hearing impaired. The display provides information about the identity of vowels spoken in isolation or in monosyllables. Vowels appear on a screen as differently located areas in a space, the coordinates of which are obtained from a dimensional analysis of vowel spectra. Resolving properties of the device, indexed by a measure of area overlap, are examined in detail. In particular, implications for differentiating utterances of male, female, and child speakers are studied. Results show that the device has promising features and is especially useful for exploring the vowel space as well as for learning a global differentiation of the vowels. The discrimination of spectrally similar vowels is limited, however. Ideas for future improvements are discussed.

Computers↗
PubMed1985

The effect of segmental and suprasegmental corrections on the intelligibility of deaf speech.

Three experiments were conducted to study the effect of segmental and suprasegmental corrections on the intelligibility and judged quality of deaf speech. By means of digital signal processing techniques, including LPC analysis, transformations of separate speech sounds, temporal structure, and intonation were carried out on 30 Dutch sentences spoken by ten deaf children. The transformed sentences were tested for intelligibility and acceptability by presenting them to inexperienced listeners. In experiment 1, LPC based reflection coefficients describing segmental characteristics of deaf speakers were replaced by those of hearing speakers. A complete segmental correction caused a dramatic increase in intelligibility from 24% to 72%, which, for a major part, was due to correction of vowels. Experiment 2 revealed that correction of temporal structure and intonation caused only a small improvement from 24% to about 34%. Combination of segmental and suprasegmental corrections yielded almost perfectly understandable sentences, due to a more than additive effect of the two corrections. Quality judgments, collected in experiment 3, were in close agreement with the intelligibility measures. The results show that, in order for these speakers to become more intelligible, improving their articulation is more important than improving their production of temporal structure and intonation.

Adolescent↗
PubMed1984

The effect of correcting fundamental frequency on the intelligibility of deaf speech and its interaction with temporal aspects.

This study investigates the role of intonation for the intelligibility of deaf speech. The intonation contours of Dutch sentences spoken by deaf children were manipulated using digital signal processing techniques, including LPC analysis. Sentence intonation was corrected by replacing the original F0 contour of the deaf utterance with an artificial contour derived from a formalized intonation grammar. Three types of intonation corrections were produced, differing with respect to the underlying accent structure and the type of F0 movements used. The overall results show that intonation correction yields a small but significant improvement in intelligibility of 7% (from 20% to 27% words correctly identified). The largest gain is obtained after removal of over-accentuations. To evaluate the interaction with temporal aspects, intonation corrections were also implemented on temporally corrected sentences. Total growth in intelligibility due to these combined corrections amounts to 13%. Thus it is concluded that no dramatic gain in intelligibility may be expected if speech pathologists succeed in teaching their deaf pupils to have better control over the suprasegmental aspects of their speech.

Adolescent↗
PubMed1981

Internal representation of simple temporal patterns.

In this study the imitation of several periodically repeating simple temporal patterns consisting of two or more intervals varying in their duration ratios has been investigated. The errors that subjects typically made in their imitations and the systematic changes that occurred during repeated imitations indicate that both musically trained and untrained subjects map temporal sequences onto an interval structure the nature of which is revealed by studying which patterns are correctly and which incorrectly reproduced. A "beat-based" model for the perception of temporal sequences is proposed. This model states that the first step in the processing of a temporal sequence consists of a segmentation of the sequence into equal intervals bordered by events. This interval is called the beat interval. How listeners select this beat interval is only partly understood. In a second step, intervals smaller than the beat interval are expressed as a subdivision of the beat interval in which they occur. The number of within-beat structures that can be represented in the model is, however, limited. Specifically, only beat intervals that are subdivided into either equal intervals or intervals in a 1:2 ratio fit within the model. The partially hierarchical model proposed, though in need of further elaborations, shows why the number of temporal patterns that can be correctly conceptualized is limited. The relation of the model to other models is discussed.

Discrimination Learning↗
PubMedDate not supplied

On the relation among speech errors, disfluencies, and self-repairs.

In this study the relationship between speech errors (deviations from a speech plan), disfluencies (interruptions in the execution of a speech plan), and self-repairs (corrections of speech errors) was examined. Two hypotheses were formulated: Either disfluencies are special types of speech errors, or they resemble self-repairs (i.e., they are corrective actions applied to anticipated, internal errors). To test these two hypotheses, patterns of speech errors, disfluencies, and self-repairs were compared in a task in which speakers recited stimulus sentences four times in succession under time pressure. Subjects in one condition were explicitly instructed to pay close attention to accuracy of speaking. In another condition subjects were told that speech accuracy was not important. A much lower speech error rate was found in the higher-accuracy condition, but rates of disfluencies and self-repairs did not differ significantly between the two accuracy conditions. This is regarded as support for the self-repair account of disfluencies. When accuracy of speaking is stressed, speakers tend to avoid and repair speech errors at the cost of reduced speech fluency.

Adolescent↗