Voice onset time in Swedish children and adults.

Voice onset time (VOT) is a temporal acoustic parameter, which reflects the timing of speech motor control. The objective of the work was to obtain normative VOT data in Swedish children. Thus, 150 children aged 8-11 years old and 36 adults were audio-recorded when producing the plosives in minimal pairs. Measures were made using waveforms and spectrograms. Results show that Swedish children developed adult-like VOT values between 9 and 10 years. By the age of 10 years prevoicing was also found to be completely adultlike in length. The results indicate that all Swedish adults do not produce voiced plosives with prevoicing. No evident gender differences were found. The obtained VOT values can be used as normative data when assessing children with speech and language disorders.

Influence of adenotonsillar hypertrophy on /s/-articulation in children--effects of surgery.

Tonsillar hypertrophy is common in young children and affects several aspects of the speech such as distortions of the dento-alveolar consonants. The study objective was to assess /s/-articulation, perceptually and acoustically, in children with tonsillar hypertrophy and compare effects of two types of surgery, total tonsillectomy and tonsillotomy. Sixty-seven children, aged 50-65 months, on the waiting list for surgery, were randomized to tonsillectomy or tonsillotomy. The speech material was collected preoperatively and 6 months postoperatively. Two groups of age-matched children were controls. /S/-articulation was affected acoustically with lower spectral peak locations and perceptually with less distinct /s/-production before surgery, in comparison to controls. After surgery /s/-articulation was normalized perceptually, but acoustic differences remained. No significant differences between surgical methods were found.

Child voice and noise: a pilot study of noise in day cares and the effects on 10 children's voice quality according to perceptual evaluation.

The purpose of this investigation was to study children's exposure to background noise at the ears during a normal day at the day care center and also to relate this to a perceptual evaluation of voice quality. Ten children, from three day care centers, with no history of hearing and speech problems or frequent infections were selected as subjects. A binaural recording technique was used with two microphones placed on both sides of the subject's head, at equal distance from the mouth. A portable digital audio tape (DAT) recorder (Sony TCD-D 100, Stockholm, Sweden) was attached to the subject's waist. Three recordings were made for each child during the day. Each recording was calibrated and started with three repetitions of three sentences containing only sonorants. The recording technique allowed separate analyses of the background noise level and of the sound pressure level (SPL) of each subjects' own voice. Results showed a mean background noise level for the three day care centers at 82.6dBA Leq, ranging from 81.5 to 83.6dBA Leq. Day care center no. 2 had the highest mean value and also the highest value at any separate recording session with a mean background noise level of 85.4dBA Leq during the noontime recordings. Perceptual evaluation showed that the children attending this day care center also received higher values on the following voice characteristics: hoarseness, breathiness, and hyperfunction. Girls increased their loudness level during the day, whereas for boys no such change could be observed.