Speech intelligibility studies in classrooms

Speech intelligibility tests and acoustical measurements were made in ten occupied classrooms. Octave-band measurements of background noise levels, early decay times, and reverberation times, as well as various early/late sound ratios, and the center time were obtained. Various octave- band useful/detrimental ratios were calculated along with the speech transmission index. The interrelationships of these measures were considered to evaluate which were most appropriate in classrooms, and the best predictors of speech intelligibility scores were identified. From these results ideal design goals for acoustical conditions for classrooms were determined either in terms of the 50-ms useful/ detrimental ratios or from combinations of the reverberation time and background noise level.Des essais d'intelligibilit\ue9 de la parole et des mesures acoustiques ont \ue9t\ue9 effectu\ue9s dans dix classes occup\ue9es. On a ainsi mesur\ue9 en bandes d'octave les niveaux de bruit ambiant, les temps d'affaiblissement initial et les temps de r\ue9verb\ue9ration, ainsi que divers rapports son initial-son subs\ue9quent et le temps du centre. Divers rapports son utile-son nuisible par bande d'octave et l'indice de transmission du son ont \ue9t\ue9 calcul\ue9s. On a \ue9tudi\ue9 les relations entre ces mesures pour pr\ue9ciser celles qui convenaient le mieux dans les classes, et on a identifi\ue9 les mesures qui permettent le mieux de pr\ue9voir les pourcentages d'intelligibilit\ue9 de la parole. Ces r\ue9sultats ont servi \ue0 d\ue9terminer les conditions acoustiques optimales pour les classes, soit en termes de rapports son utile-son nuisible de 50 ms, soit gr\ue2ce \ue0 des combinaisons du temps de r\ue9verb\ue9ration et du niveau de bruit ambiant.Peer reviewed: YesNRC publication: Ye