This study was concerned with predicting loudspeaker directivity in theatre sound systems. / The experimental question was "How is a loudspeaker's directivity affected by the absorptivity of the walls adjacent to the loudspeaker?" The initial experimental hypothesis was "The directivity will increase as absorption is added to the walls." But although the initial experimental hypothesis proved false, the experimental data suggested a simple formula by which the directivity of a loudspeaker may be predicted from data provided by the manufacturer. / The method consisted of measuring the output of a loudspeaker to determine its "Q", or directivity. The Altec A-7 loudspeaker was first placed against a reflective surface and measured for Q. Then sound absorbing material was placed against the reflective surface, and the measurements were repeated. Measurements were taken in three boundary situations: against one wall, at the intersection of two walls, and in a corner. Measurements were also taken in free air (no walls adjacent to the loudspeaker) to determine the loudspeaker's free air Q. / It was determined that for any of the tested values of Q, and for any level of absorptivity, the directivity of a loudspeaker could be determined mathematically by simply multiplying the "Q" of the loudspeaker in free air by a constant derived from the volume of air into which a loudspeaker placed against one or more walls necessarily operates. The "Q" of a loudspeaker placed against one wall is increased by a factor of two; at the intersection of two walls, four, and in a corner, eight. This constant seems to be valid for any free air "Q" and any level of absorption, within the tolerance of the measurements. / Source: Dissertation Abstracts International, Volume: 48-12, Section: A, page: 3011. / Thesis (Ph.D.)--The Florida State University, 1987.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76179 |
| Contributors | RAND, HERBERT CARLETON, II., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 383 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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