Speech intelligibility of guide audio with parametric loudspeakers

• Autores: Kazuhiro Kondo, Tomohiro Terada, Futari Kano
• Localización: Noise Control Engineering Journal, ISSN 0736-2501, Vol. 60, Nº. 5, 2012, págs. 548-558
• Idioma: inglés
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• Resumen

  • We are investigating the application of super-directive parametric speakers for effective presentation of simultaneous guide audio in public places, such as museums. Unlike conventional loudspeakers, from which sound will spread in all directions, parametric speakers carry audio in a very narrow directed beam by modulation of audible sound with ultrasonic carriers. The audible sound is obtained when this modulated wave is gradually demodulated while traveling through air. This speaker is ideal for presenting guide audio in museums, for instance, since the audio from neighboring exhibits will not interfere with other guide audio. Accordingly, we initially evaluated the speech intelligibility in simulated parallel audio presentation from two parametric speakers placed on the ceiling facing directly downwards, and found that the reflection from the floor significantly degrades the intelligibility. We then oriented the speakers diagonally so that the reflections will travel outside the audible range. We found that intelligibility improves with proper orientation. We also investigated the use of low reflection material on the floor, e.g. carpets, and found that this also gives additional intelligibility improvement over reflective material, e.g. wood. These all give some guidelines to the optimum placement and orientation of parallel parametric speakers, as well as the preferred floor material for applications using these speakers, such as guide audio applications.