Sentence perception in listening conditions having similar speech intelligibility indices

Abstract

Abstract

Objective: The objective of this study was to examine the relation between bandwidth and speech perception in normally hearing adults and children at a single value of the Speech Intelligibility Index (SII). Design: The SII of meaningful and nonsense sentences were held constant for each of three bandwidths to test the hypothesis that perception would be equivalent in each condition. The sentences were filtered to produce three bandwidth conditions (low-pass cut-off frequency: 0.8, 1.25, 2.5 kHz) and the sensation level within each bandwidth was adjusted to produce a similar SII (0.43–0.48). Sentences were presented in broadband noise to facilitate equivalent audibility across subjects in each bandwidth condition. Study sample: Participants were 20 adults between the ages of 19 and 47 years and 20 eight-year-old children. All participants had normal hearing. Results and conclusion: Contrary to the hypothesis, performance of both groups increased significantly as bandwidth increased. Significant main effects of group and sentence type were also found. These results indicate that performance was governed largely by the bandwidth of the stimuli and that those effects were not represented well in the SII.

Sumario

Objetivo: El objetivo de este estudio fue examinar la relación entre el ancho de banda y la percepción del lenguaje en adultos normoyentes y niños, con un valor único del Índice de Inteligibilidad del Habla (SII). Diseño: El SII de oraciones con y sin sentido se mantuvo constante para cada uno de los tres anchos de banda para probar la hipótesis de que la percepción puede ser equivalente en cada condición. Las oraciones fueron filtradas para producir tres condiciones de ancho de banda (filtro pasa-bajo a frecuencias: 0.8, 1.25, 2.5 kHz) y el nivel de sensación en cada ancho de banda fue ajustado para producir un SII similar (0.43–0.48). Se presentaron las oraciones en medio de ruido de banda ancha para facilitar la audibilidad equivalente entre sujetos en cada condición de ancho de banda. Muestra: Los participantes fueron 20 adultos de edades entre 19 y 47 años y veinte niños de ocho años de edad. Todos eran normoyentes. Resultados y conclusiones: Contrario a la hipótesis, el desempeño de los dos grupos aumentó significativamente conforme el ancho de banda aumentaba. También se encontraron efectos significativos mayores en cuanto a grupos y tipo de oración. Estos resultados indican que esos efectos no estaban bien representados en el SII.

Key Words::

• Children
• Adults
• Speech intelligibility index
• Bandwidth
• Speech perception

Acknowledgements

This work was supported in part by a grant from Women in Philanthropy (Access to Undergraduate Research Scholarship: 2008). Special thanks to Drs. Terry Wiley and Michael Dorman for their comments during the early stages of the project.

Declaration of Interest: The authors report no conflicts of interest. The authors are responsible for the content and writing of the paper.