Monday, October 13 4:00 pm 5:30 pm
Session R Sound Reinforcement
R-1 A Method of Loudspeaker Directivity Prediction Based on Huygens-Fresnel PrincipleArkady Gloukhov, Consultant, St. Petersburg, Russia
In accordance with the Huygens-Fresnel principle, the radiating device is simulated as an array of point sources in the aperture. The aperture complex pressure can be calculated by means of a model of wave propagation along the waveguide based on the Huygens-Fresnel principle or by means of approximating waveguide procedure using experimental polar data in a traditional form. The method predicts dispersion pattern at any distance with any needed resolution. Phase patterns as well as dispersion versus distance relationship are demonstrated on samples. Proposed algorithms can be used in high-resolution simulators of loudspeakers and arrays. Results also point to another approach of measurements and presentation of dispersion data.
R-2 Some Effects of Equalization on Sound System Intelligibility and MeasurementPeter Mapp, Peter Mapp Associates, Colchester, UK
Although it is well known that equalizing a sound system can significantly affect the perceived sound quality and intelligibility, surprisingly there is little or no information relating to the degree of improvement in intelligibility that can be achieved. Measurement data relating to over 30 sound systems has been reviewed and a number of factors relating to typical response anomalies identified. Large discrepancies were often noted to occur between the measured in-room sound system or loudspeaker response and published anechoic frequency response data. The underlying causes and implications relating to speech intelligibility are discussed. The results of a pilot study illustrating the improvements that appropriate equalization can produce are presented. It is shown that under some conditions, improvements of over 20 percent in speech intelligibility can be achieved. However, it is also noted that none of the current electro-acoustically based measurement metrics, including STI, % Alcons, STIPa or RaSTI correctly indicate the intelligibility improvements that system equalization produces.