Communication Sciences

Permanent URI for this collectionhttps://hdl.handle.net/11274/15391

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Browsing Communication Sciences by Author "Assmann, Peter F."

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    Analysis of a vowel database
    (Canadian Acoustical Association, 2008) Assmann, Peter F.; Nearey, Terrance M.; Bharadwaj, Sneha
    The perceptual effects of upward and downward scaling of the formats in combination with changes in geometric mean fundamental frequency was investigated. A database of recordings from adults and children from the Dallas, Texas region was collected. A systematic relationship between the geometric mean of the format frequencies across all of the vowels for a given speaker and the geometric mean fundamental frequency was found. Vowels were recorded in hVd words, both in isolation and in a carrier sentence. Recordings were carried out over a 2.5-year period at the University of Texas at Dallas. Each recorded token was produced following a screen prompt that displayed the orthographic representation of the hVd word or sentence, along with an audio example spoken by an adult female from the Dallas area. It was observed that the geometric mean increases linearly with the geometric mean of the formant frequencies when data for males and females are combined.
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    Effects of auditory feedback deprivation length on the vowel ∕ε∕ produced by pediatric cochlear-implant users
    (Acoustical Society of America, 2007) Bharadwaj, Sneha V.; Graves, Amanda G.; Bauer, Delia D.; Assmann, Peter F.
    Effects of auditory deprivation on speech production by ten cochlear-implanted children were investigated by turning off the implant for durations ranging from 0.3 to 5.0s and measuring the formant frequencies (F1 and F2) of the vowel ∕ε∕. In five of the ten talkers, F1 and/or F2 shifted when auditory feedback was eliminated. Without feedback, F2 frequency lowered consistently, suggesting vowel centralization. Phonetic transcription indicated that some of these acoustic changes led to perceptible shifts in phonetic quality. The results provide evidence that brief periods of auditory deprivation can produce perceptible changes in vowels produced by some cochlear-implanted children.
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    Effects of auditory feedback on fricatives produced by cochlear-implanted adults and children: Acoustic and perceptual evidence
    (Acoustical Society of America, 2006-02) Bharadwaj, Sneha V.; Tobey, Emily A.; Assmann, Peter F.; Katz, William F.
    Acoustic analyses and perception experiments were conducted to determine the effects of brief deprivation of auditory feedback on fricatives produced by cochlear implant users. The words /si/ and /ʃi/ were recorded by four children and four adults with their cochlear implant speech processor turned on or off. In the processor-off condition, word durations increased significantly for a majority of talkers. These increases were greater for children compared to adults, suggesting that children may rely on auditory feedback to a greater extent than adults. Significant differences in spectral measures of /ʃ/ were found between processor-on and processor-off conditions for two of the four children and for one of the four adults. These talkers also demonstrated a larger /s/-/ʃ/ contrast in centroid values compared to the other talkers within their respective groups. This finding may indicate that talkers who produce fine spectral distinctions are able to perceive these distinctions through their implants and to use this feedback to fine tune their speech. Two listening experiments provided evidence that some of the acoustic changes were perceptible to normal-hearing listeners. Taken together, these experiments indicate that for certain cochlear-implant users the brief absence of auditory feedback may lead to perceptible modifications in fricative consonants.