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| 2. |
- Ternström, Sten, et al.
(författare)
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Cancellation of simulated environmental noise as a tool for measuring vocal performance during noise exposure
- 2002
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Ingår i: Journal of Voice. - 0892-1997 .- 1873-4588. ; 16:2, s. 195-206
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Tidskriftsartikel (refereegranskat)abstract
- It can be difficult for the voice clinician to observe or measure how a patient uses his voice in a noisy environment. We consider here a novel method for obtaining this information in the laboratory. Worksite noise and filtered white noise were reproduced over high-fidelity loudspeakers. In this noise, I I subjects read an instructional text of 1.5 to 2 minutes duration, as if addressing a group of people. Using channel estimation techniques, the site noise was suppressed from the recording, and the voice signal alone was recovered. The attainable noise rejection is limited only by the precision of the experimental setup, which includes the need for the subject to remain still so as not to perturb the estimated acoustic channel. This feasibility study, with 7 female and 4 male subjects, showed that small displacements of the speaker's body, even breathing, impose a practical limit on the attainable noise rejection. The noise rejection was typically 30 dB and maximally 40 dB down over the entire voice spectrum. Recordings thus processed were clean enough to permit voice analysis with the long-time average spectrum and the computerized phonetogram. The effects of site noise on voice sound pressure level, fundamental frequency, long-term average spectrum centroid, phonetogram area, and phonation time were much as expected, but with some interesting differences between females and males.
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| 4. |
- Szabo, Annika, 1972-, et al.
(författare)
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A voice accumulator device : evaluation based on studio and field recordings.
- 2001
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Ingår i: Logopedics, Phoniatrics, Vocology. - : Informa UK Limited. - 1401-5439 .- 1651-2022. ; 26:3, s. 102-117
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Tidskriftsartikel (refereegranskat)abstract
- A voice accumulator is a portable device for long-term measurements of voice use in natural conditions. A contact microphone attached to the front part of the neck registers vocal fold vibrations. The purposes of the present study were: 1) to evaluate the voice accumulator's two measuring programs optimized for registration of fundamental frequency (F0) and phonation time, respectively; and 2) to test the voice accumulator for field recordings. Four healthy subjects were recorded in a sound-proof booth simultaneously with one contact microphone into a voice accumulator and one contact microphone into a computer. In terms of F0 and phonation time, the results showed that correlations between the voice accumulator's two measuring programs and a signal-processing program were high (r > or = 0.85) for all subjects but one. The inter-subject variability was large. A prerequisite for reliable vocal fold vibration detection by the voice accumulator was a careful placement and a firm attachment of the contact microphone on the neck. Four subjects were recorded with the voice accumulator during a working day. It was concluded that the voice accumulator is an overall good instrument for measurements of F0 and phonation time, and thus is useful for both clinical work and research.
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| 5. |
- Södersten, M., et al.
(författare)
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Vocal behavior and vocal loading factors for preschool teachers at work studied with binaural DAT recordings
- 2002
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Ingår i: Journal of Voice. - : Mosby. - 0892-1997 .- 1873-4588. ; 16:3, s. 356-371
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Tidskriftsartikel (refereegranskat)abstract
- Preschool teachers are at risk for developing voice problems such as vocal fatigue and vocal nodules. The purpose of this report was to study preschool teachers' voice use during work. Ten healthy female preschool teachers working at daycare centers (DCC) served as subjects. A binaural recording technique was used. Two microphones were placed on both sides of the subject's head, at equal distance from the mouth, and a portable DAT recorder was attached to the subject's waist. Recordings were made of a standard reading passage before work (baseline) and of spontaneous speech during work. The recording technique allowed separate analyses of the level of the background noise, and of the subjects' voice sound pressure level, mean fundamental frequency, and total phonation time. Among the results, mean background noise level for the ten DCCs was 76.1 dBA (range 73.0-78.2), which is more than 20 dB higher than what is recommended where speech communication is important (50-55 dBA). The subjects spoke on an average of 9.1 dB louder (p < 0.0001), and with higher mean fundamental frequency (247 Hz) during work as compared to the baseline (202 Hz) (p < 0.0001). Mean phonation time for the group was 17%, which was considered high. It was concluded that preschool teachers do have a highly vocally demanding profession. Important steps to reduce the vocal loading for this occupation would be to decrease the background noise levels and include pauses so that preschool teachers can rest their voices.
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