Gender differences in children's voice use in a day care environment.

BACKGROUND: The prevalence of dysphonia is higher in boys than in girls before puberty. This could be because of the differences in boys' and girls' voice use. Previous research on gender differences in prepubescent children's voice parameters has been contradictory. Most studies have focused on examining fundamental frequency. OBJECTIVES: The purpose of this study was to investigate voice use in boys and girls in a day care environment based on the voice parameters fundamental frequency (Hz), vocal intensity (dB SPL), and phonation time (%) and to ascertain whether there were any significant gender differences. STUDY DESIGN: Prospective comparative design. METHOD: The study was conducted in a day care environment where 30 children (17 boys and 13 girls aged 4-5 years) participated. The participants' voices were measured continuously for 4 hours with a voice accumulator that registered fundamental frequency, vocal intensity level, phonation time, and background noise. RESULTS: Mean (standard deviation) fundamental frequency was 310 (22) and 321 (16) Hz, vocal intensity was 93 (4) and 91 (3) dB SPL, and phonation time was 7.7 (2.0)% and 7.6 (2.5)% for boys and girls, respectively. No differences between genders were statistically significant. CONCLUSION: The finding of no statistically significant gender differences for measurements of voice parameters in a group of children aged 4-5 years in a day care environment is an important finding that contributes to increased knowledge about young boys' and girls' voice use.

Observations of the relationship between noise exposure and preschool teacher voice usage in day-care center environments.

Although the relationship between noise exposure and vocal behavior (the Lombard effect) is well established, actual vocal behavior in the workplace is still relatively unexamined. The first purpose of this study was to investigate correlations between noise level and both voice level and voice average fundamental frequency (F0) for a population of preschool teachers in their normal workplace. The second purpose was to study the vocal behavior of each teacher to investigate whether individual vocal behaviors or certain patterns could be identified. Voice and noise data were obtained for female preschool teachers (n=13) in their workplace, using wearable measurement equipment. Correlations between noise level and voice level, and between voice level and F0, were calculated for each participant and ranged from 0.07 to 0.87 for voice level and from 0.11 to 0.78 for F0. The large spread of the correlation coefficients indicates that the teachers react individually to the noise exposure. For example, some teachers increase their voice-to-noise level ratio when the noise is reduced, whereas others do not.

Mean F0 values obtained through standard phrase pronunciation compared with values obtained from the normal work environment: a study on teacher and child voices performed in a preschool environment.

Mean fundamental frequency (F(0)) values are often used in research on vocal load. In this study, we examine how the mean F(0) differs when evaluated through pronouncing a standard phrase as compared to the mean F(0) obtained in a real work/play environment. We also examine how the F(0) values change throughout the day. The study was performed in a preschool, nine adult female preschool teachers and 11 children participated. The participants wore a digital recorder equipped with an accelerometer, which was attached to the neck. In the study, the participant first pronounced a standard phrase in a controlled environment; thereafter, the voice was recorded in the environment where both children and adults normally reside throughout the day, denoted by the work/play environment. For each participant, the procedure was repeated four times throughout the day. Analyses showed that the F(0) values of the children's and adult's voices were significantly higher when recorded in the work/play environment as compared to the controlled environment. The average difference was 36 Hz for adults and 24 Hz for children. Previous studies have shown an increase of F(0) over the day for teachers. In this study, an increase between morning and afternoon values was found amounting to 8 Hz for adults and 24 Hz for children. For the child population, this increase was statistically significant. However, the total changes over the day revealed a somewhat more complex scheme, with an increase of F(0) in the morning, a decrease during lunch, and finally an increase in the afternoon. This pattern was verified statistically for the joint child-adult population.

Comparison of two methods of voice activity detection in field studies.

PURPOSE: To evaluate and compare the performance of 2 methods of voice activity detection (neck-attached accelerometer vs. binaural recordings) in field studies in environments where voice activity normally occurs. METHOD: A group of 11 healthy adults wore recording equipment during their lunch break. We used binary classification to analyze the results from the 2 methods. The output was compared to a gold standard, obtained through listening tests, and the probability for sensitivity (Ps) and false positive (Pf) was rated. The binary classifiers were set for consistent sensitivity of 99%; thus, the lower false positive rate would indicate the method with the better performance. RESULTS: The neck-attached accelerometer (Pf = 0.5%) performed significantly (p < .001) better than the binaural method (Pf = 7%). CONCLUSION: The neck-attached accelerometer is more suitable than the binaural method for voice assessments in environments where people are speaking in close proximity to each other and where the signal-to-noise ratio is moderate to low.