Listening to aliasing: music examples
Below, we demonstrate aliasing (due to undersampling) for two short pieces of music: (1) a short segment of Kenny Roger's "The Gambler," and (2) a short segment of some Cantonese opera. For these examples, we first resampled each piece of music to 48kHz (from 44.1kHz); note that this step does not add any information to the signal, but merely simplifies the process of down-sampling. Then, we down-sampled each piece of music to 8kHz, 4kHz and 2kHz in two different ways: (1) with low-pass filtering prior to down-sampling and (2) without low-pass filtering. The examples with low-pass filtering are referred to as anti-aliased, since the low-pass filtering prior to down-sampling ensures that no high-frequency aliases appear in the reconstructed signal. Listening to these two different versions at each lower sampling frequency, we can definitely hear distortion (aliasing) in the examples where no low-pass filtering was applied prior to down-sampling, while such distortion is not evident in the anti-aliased (low-pass filtered) examples.
Kenny Roger's "The Gambler" (23 sec.)
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Sampling rate |
Anti-aliased |
Aliased (no low-pass filtering) |
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48kHz |
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N/A |
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8kHz |
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4kHz |
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2kHz |
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Cantonese Opera (10 sec.)
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Sampling rate |
Anti-aliased |
Aliased (no low-pass filtering) |
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48kHz |
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N/A |
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8kHz |
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4kHz |
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2kHz |
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Last updated February 3, 2003 by Michael C. Nechyba