Age effect on students’ intelligibility listening to a teacher with a dysphonic voice

Abstract

The purpose of this project is to assess the acoustical conditions in which optimal intelligibility and low listening effort can be achieved in real classrooms for elementary students, taking into consideration the effects of dysphonic voice and typical classroom noise. Speech intelligibility tests were performed in classrooms with 80 normal-hearing students (7–11 years old). The speech material was produced by a female actor using a normal voice quality and simulating a dysphonic voice. The stimuli were played by a Head and Torso Simulator. Child babble noise and classrooms with different reverberation times were used to obtain a Speech Transmission Index range from 0.2 to 0.7. The results showed a significant decrease in intelligibility when the speaker was dysphonic, in STI higher than 0.33. The rating of listening difficulty showed a significantly greater effort in perceiving the dysphonic voice. Younger children showed poorer performance and greater listening difficulty compared to older children when listening to the normal voice quality. Both groups were equally impacted when the voice was dysphonic. The results suggested that better acoustic conditions are needed for children to reach a good level of intelligibility and to reduce listening effort if the teacher is suffering from voice problems.