In order to model nonlinearities in loudspeakers, accurate measurement of harmonic distortion is necessary with particular attention to the relative phases of fundamental and harmonics. This paper outlines several ways that logarithmic sweeps can be used to achieve this goal. It is shown that Novak’s redesign of the logsweep is not strictly necessary, if proper account is taken of the phase relationships of the various harmonics. We study several other types of sweeps and methods to extract precise harmonic amplitudes and phases, using tracking filter concepts. The paper also deals with measurement systems that may have fractional-sample delays between excitation, reference, and data channels. Such details are important for accurate phase characterization of transfer functions. An intermodulation example is given for which sweeps with a single instantaneous frequency are inadequate.

Authors: Vanderkooy, John; Thomson, Sean
Affiliations: University of Waterloo, Waterloo, ON, Canada; B&W Group Ltd., Steyning, West Sussex, UK(See document for exact affiliation information.)
AES Convention: 140 (May 2016) Paper Number: 9497
Publication Date: May 26, 2016 Import into BibTeX
Subject: Instrumentation and Measurement
Permalink: https://www.aes.org/e-lib/browse.cfm?elib=18196

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