Method and apparatus for testing and evaluating loudspeaker performance
US4130023A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 27, 1977 |
| Grant date | Dec 19, 1978 |
| Priority date | — |
| Expiry date | Dec 27, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01M99/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for determining the directivity index (DI) and directivity factor (Q) of a loudspeaker is described. A microphone is placed in the throat of a horn-type loudspeaker to measure the acoustical pressure at this point. A second microphone is placed along an extension of a central axis of a loudspeaker at a predetermined distance from the mouth of the loudspeaker to measure the acoustical pressure at this point. The output of each of the microphones is rectified and converted to decibel form. The decibel signal representing acoustical pressure at the throat is subtracted from the signal representing the measured pressure at the predetermined distance. A signal (in decibel form) representing the distance of the second microphone from the mouth of the horn is added to the difference signal and a signal (in decibel form) in accordance with the diameter of the loudspeaker throat is subtracted from the difference signal to provide a signal in accordance with directivity index. From the directivity index a signal in accordance with directivity factor (Q), which is a power ratio, can be derived.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.