Spatial benefits on speech intelligibility in real classroom acoustics under energetic and informational masking noise

Challenging acoustic conditions, i.e. high noise and long reverberation time, negatively affect speech intelligibility. This is particularly true for school environments where learning is delivered, and students of every age develop their cognitive abilities. Research has primarily focused on the effect of reverberation and noise on speech intelligibility and on the spatial release from masking under laboratory conditions, whereas few studies considered these aspects ecologically. Also, the effect of noise on speech intelligibility was widely investigated considering its energetic rather than its informative content. This work deepens the extent to which the spatial release from masking is affected by reverberation and noise under real classroom acoustics, in order to help the design of learning environments to enhance speech intelligibility. Binaural room impulse responses were acquired at increasing speaker-to-listener distances, with noise sources at 0, 120 and 180 from the listener's head, in classrooms with reverberation times ranging from 0.4 s to 3.5 s, as to represent the typical conditions of Italian schools. Then, listening tests were performed: the impulse responses were convolved with speech and noise anechoic stimuli, and presented via headphone to a selected panel of normal hearing adults. Further analyses are now in progress; preliminary results reveal that speech intelligibility is worse under higher reverberation times and, averagely, under informational masking noise, as expected. As far as the spatial release from masking is concerned, when longer reverberation times are present in the room there is a tendency to have greater benefits under informational noise.