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.)

Sampling rate Anti-aliased Aliased (no low-pass filtering)
48kHz
(mp3, 228 kb)
(wav, 2.1 Mb) 		N/A
8kHz
(mp3, 232 kb)
(wav, 360 kb)
(mp3, 232 kb)
(wav, 364 kb)
4kHz
(mp3, 232 kb)
(wav, 184 kb)
(mp3, 232 kb)
(wav, 184 kb)
2kHz
(mp3, 232 kb)
(wav, 92 kb)
(mp3, 232 kb)
(wav, 92 kb)

Cantonese Opera (10 sec.)

Sampling rate Anti-aliased Aliased (no low-pass filtering)
48kHz
(mp3, 108 kb)
(wav, 1.0 Mb) 		N/A
8kHz
(mp3, 112 kb)
(wav, 172 kb)
(mp3, 112 kb)
(wav, 172 kb)
4kHz
(mp3, 112 kb)
(wav, 88 kb)
(mp3, 112 kb)
(wav, 88 kb)
2kHz
(mp3, 112 kb)
(wav, 44 kb)
(mp3, 112 kb)
(wav, 44 kb)
Last updated February 3, 2003 by Michael C. Nechyba