Roughness of Amplitude Modulated Tones
Sound advice? Or an audio course with a coarse tone? Listen and learn.
Join the DZone community and get the full member experience.
Join For FreeA recent post pointed out that two pure tones that are fairly close in pitch create a rough sound. The roughness increases with the frequency difference, up to a point, then decreases.
This post will look at a roughness in a different setting, amplitude modulation. Several psychoacoustics researchers have suggested that perceived roughness increases as a power of modulation depth, up to a maximum. That is,
where the signal is
![[1 + m\cos(2\pi f_m t)] \cos(2\pi f_c t)](http://www.johndcook.com/modulation_depth.png){kind=small}
Some have suggested, based on empirical studies, that p = 2, while other have suggested thatp varies as a function of the frequency fc of the carrier wave.
Here is an audio (.wav) file where the the modulation depth varies as a function of time, m = 0.1t where t is time in seconds.
In this example the carrier frequency fc is 1000 Hz and the modulation frequency fm is 60 Hz.
Reference: Psychoacoustical Roughness: Implementation of an Optimized Model. P. Daniel and R. Weber. Acoustia 83 (1997) 113–123
Published at DZone with permission of John Cook. See the original article here.
Opinions expressed by DZone contributors are their own.
Comments