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Sound Noise-Masking Experiments

March 29th Fact-of-the-Day

Egan and Hake conducted a series of sound-signal noise-masking experiments in 1950 that showed that noise which is closest in frequency to the frequency of a sound signal has the greatest signal-masking effect (makes the signal most difficult for humans to hear). That finding was confirmed in experiments conducted by Fletcher in 1953. Those experimenters also found that the masking effect of single-frequency noise covers a relatively narrow band of frequencies if the noise has low amplitude, but that the masked frequency band widens with increasing noise amplitude. That finding won't surprise anyone accustomed to listening to signals through noise. However, what may be surprising to most people is that they found that noise masking with human hearing is not symmetrical about a noise frequency, but instead spans much farther above, than below. ©2005 Martek, International. All rights reserved.

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