Virtual Instruments for Audio Testing

Although Virtual Instruments have been part of SoundCheck as long as most of us can remember, back in 1998 this was a huge innovation. This paper introduces the concept at a time when computerized audio measurement was a novel concept.

Authors: Steve Temme
Presented at the 105th AES Convention, San Francisco, 1998

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How to Graph Distortion Measurements

Distortion curves are conventionally plotted under the corresponding excitation frequency of the measured fundamental. Interpretation of results can be misleading due to the influence that the passband shape and amplitude irregularities of the fundamental response have on the distortion responses. By ‘amplitude normalizing’ the distortion responses to the measured fundamental response before plotting them at the excitation frequency, distortion graphs become easier to interpret for diagnostic purposes. In addition, the distortion curves become insensitive to room reflections in the measured responses.

Authors: Steve Temme
Presented at the 94th AES Convention, Berlin, 1993

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Simulated Free Field Measurements

The development of time selective techniques has enabled measurements of the free field response of a loudspeaker to be performed without the need for an anechoic chamber. The low frequency resolution of both time selective techniques and anechoic measurements is, however, limited by the size of the room. A technique is presented enabling measurements of the complex free field response of the loudspeaker to be performed, without an anechoic room, throughout the entire audio frequency range. It is shown that this technique can also be used for measurements of harmonic distortion.

Authors: Christopher J. Struck and Steve Temme
Presented at the 93rd AES Convention, San Francisco, 1992

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