---------------------------- Original Message ---------------------------- Subject: Re: [music-dsp] Cheap spectral centroid recipe From: "Risto Holopainen" <ebel...@ristoid.net> Date: Fri, February 19, 2016 7:45 am To: music-dsp@music.columbia.edu -------------------------------------------------------------------------- > > I don't recall having seen the spectral centroid being normalized to > fundamental frequency in the literature, although in some cases it would make > sense to normalize it to the sampling frequency so that its range is [0,1]. > One could use the time domain crest factor as a measure related to brightness independently of fundamental frequency. Several other descriptors seem to be quite similar to the centroid, such as spectral slope, spectral roll-off or zero crossing rate. I can think of applications such as perceptual research where their differences matter a great deal, and other applications where you would just pick the descriptor that is most mathematically elegant or easy to implement. > � the earliest use of the concept i have ever read is that by James Beauchamp back in the 80s:�http://www.aes.org/e-lib/browse.cfm?elib=11967� Synthesis by Amplitude and "Brightness" Matching of Analyzed Musical Instrument Tones � Time-variant index and amplitude parameters for a computer model are calculated by matching the instantaneous spectral center ("brightness") of a synthetic tone and minimizing the rms error with respect to an original tone. Synthesis accuracy is gauged by measuring the difference between the spectra of the original synthetic tones and by listening tests. Nonlinear and FM synthesis models are compared by means of graphics and taped examples. � J. W. Beauchamp, "Brass Tone Synthesis by Spectrum Evolution Matching with Nonlinear Functions", in Foundations of Computer Music, C. Roads and J. Strawn, eds., MIT Press, Cambridge, MA, pp. 95-113 (1985). � � geez, i wish i could cut and paste text without getting all of that HTML crap in there. �i dunno how this is going through majordomo or whatever Douglas has running the list. � anyway, this measure of "brightness" or the "instantaneous spectral center" *was* normalized to the fundamental and the idea was to crank up the FM modulation index so that it would have the same spectral center. � -- r b-j � � � � � � � � �r...@audioimagination.com � � � "Imagination is more important than knowledge." �
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