Loose Particle Detection

During the loudspeaker manufacturing process, particles may become trapped inside the loudspeaker, resulting in a distinctive defect that is easily heard but difficult to measure. To give a clearer view of the problem, Time-Frequency maps are shown for some defective loudspeakers. Based on this analysis, a reliable testing procedure using a swept-sine stimulus, high-pass filter, and RMS-envelope analysis is presented. Further possible enhancements and applications of the method are listed.

Authors: Pascal Brunet, Evan Chakroff and Steve Temme
Presented at the 115th AES Convention, New York, 2003

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Simultaneous measurement of impulse response and distortion with a swept-sine technique

This landmark paper by Angelo Farina discusses the benefits of the Log Sine Sweep (also known as Frequency Log Sweep or Log Chirp), one of the test signals available in SoundCheck.
A novel measurement technique of the transfer function of weakly not-linear, approximately time-invariant systems is presented. The method is implemented with low-cost instrumentation; it is based on an exponentially-swept sine signal. It is applicable to loudspeakers and other audio components, but also to room acoustics measurements. The paper presents theoretical description of the method and experimental verification in comparison with MLS.

Authors: Angelo Farina
Presented at the 108th AES Convention, Paris, 2000

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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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