Harmonic Distortion Measurement: The effects of sampling rate and stimulus frequency on the measured harmonic frequency (including THD and Rub & Buzz)

Author: Steve Temme

Harmonic distortion measurements can be confusing to interpret, and it’s important to understand the data that you are looking at, particularly the relationship between the stimulus frequency and the measured harmonic frequency. This brief guide explains the relationships between sampling rate, stimulus frequency and measured harmonics for both normalized and conventional harmonic distortion measurements.

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Audio Test Stimuli – An Overview

Stweep Stepped Sine Wave Stimulus

Stweep Stepped Sine Wave Stimulus

Author: Steve Temme

Most audio analysis systems offer a wide range of stimulus option, and selecting the right one can be daunting. This overview explains the different stimulus types, what the waveforms look and sound like (click the speaker icon to hear the sound), the advantages and disadvantages of each and when you would be likely to select each one.

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Evaluation of Loudspeaker Performance at Low Frequencies

Authors: Steve Temme and Christopher J Struck

Evaluation of loudspeaker performance at low frequencies is complicated by long wavelengths, room interaction and cabinet/baffle diffraction. Since low frequency measurements have traditionally required large, impractical testing environments, different techniques have been developed in an attempt to overcome this requirement. Anechoic chambers, outdoor measurements, half-space measurements, ground plane measurements, cepstral liftering, parametric modelling and near field techniques are compared with respect to accuracy, speed, bandwidth and practical implementation.
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Audio Distortion Measurements

Author: Steve Temme

In the never ending quest for better sound transmission, reinforcement, and reproduction, the electronics have been extensively analyzed for distortion. Distortion in the electroacoustic transducers, while typically several orders of magnitude greater, has often been neglected or not even specified because it has been difficult to measure and interpret. With a basic understanding of transducer limitations, some knowledge of human hearing, and the application of different distortion test methods, electroacoustic transducer distortion becomes easier to measure and assess. Note: Although this paper was written over 20 years ago, the principles are still true today.
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