Biomedical subjects

R A Bladon

Publications and source records attributed to R A Bladon.

3 recordsLinked to original sources

PubMed1990

Relational spectral features for place of articulation in nasal consonants.

Much recent research on acoustic cues for consonants' places of articulation has focused upon the nature of the rapid spectral changes that take place between signal portions corresponding to consonantal closure and adjacent vowels. The study reported here builds on the foundation laid by earlier studies that have explored techniques for representing spectral change and for classifying place of articulation of nasal consonants using features extracted from rapid spectral changes that take place over murmur-to-vowel transitions. A new procedure is reported that avoids the use of predetermined absolute frequency bands in deriving parameters of spectral change in nasals. In experiments using the speech of 20 female and 20 male talkers, in a variety of physical and perceptual spectral scalings, application of the new procedure results in 77% correct classification of place of articulation of syllable-initial nasals and 51% correct classification of place of articulation of syllable-final nasals (for which there is a three-way contrast). Tested on the same data, a technique using predetermined absolute frequency bands produced 72% correct classification of syllable-initial nasals.

Female↗

PubMed1988

A case of foreign accent syndrome, with follow-up clinical, neuropsychological and phonetic descriptions.

We report a comparatively 'pure' case of 'foreign accent syndrome' (FAS) in a right-handed patient who sustained a small, isolated, left basal ganglia infarct. At 3 weeks post-onset FAS persisted in the absence of aphasic disorder. Phonetic analysis of the patient's speech was undertaken at that time and a further, more detailed acoustic and phonetic investigation, was undertaken at 8 months. The validity and significance of the term 'FAS' is discussed.

Adult↗

PubMed1981

Modeling the judgment of vowel quality differences.

The hypothesis of this study is that the auditory cues relevant to listeners' judgment of vowel quality are a spectral representation of loudness density versus pitch. A model is described that generates such patterns for steady-state vowels. In addition to the nonlinear transformations underlying the loudness density and pitch scales, it incorporates experimentally established characteristics associated with frequency resolution and masking, such as the critical band concept. This model is combined with a measure of auditory perceptual distance which, operating on pairs of vowels, treats each stimulus representation as a single spectral shape. In order to test the distance metric and the model, experimental data were gathered from listeners' numerical estimates of quality differences between stimulus pairs which compared four-formant and two-formant vowels. The correlation between experimental and theoretical results was 0.89. We interpret this value to indicate that the present definition of auditory cue and auditory distance can be said to account for the experimental behavior of our listeners only in a rather gross fashion. On the other hand, the theory was developed on the basis of rather conservative assumptions about the nature of auditory cues. For instance, the model ignores the possibility of temporal coding and certain nonlinear effects, and it does not pay special attention to spectral peaks. Seen in that light, the agreement between observed and predicted auditory distance is remarkably good.

Auditory Perception↗