Jun 18 2008 | 8:24 pm

Hello, I am trying to build a vocoder and was wondering how I might divide the frequency spectrum up according to its loudness as opposed to frequency? For instance, if I wanted 8 bands in my vocoder, is there an equation I can use to determine the best possible frequency spectrum for each band?

- Jun 19 2008 | 1:53 amYou could research "Bark" of "Mel" coefficients. They help slice thespectrum in 24 bands. They are designed by taking into account thesensibility of human ears. But I'm not sure that's what you are looking for,though.--http://www.jeanfrancoischarles.comJune 14th update: Ballade for clarinetist dancer - Video> Hello, I am trying to build a vocoder and was wondering how I might divide the> frequency spectrum up according to its loudness as opposed to frequency? For> instance, if I wanted 8 bands in my vocoder, is there an equation I can use to> determine the best possible frequency spectrum for each band?> --> -k.
- Jun 19 2008 | 2:22 amThat's exactly what I'm looking for. Since human hearing is logarithmic (lower frequencies are much louder and more distinct than higher frequencies), I am looking for a method to divide the frequencies so that each frequency range contains the same amount of energy. Though I've decided to just make the frequencies variables, as their manipulation mid-vocoding could most likely produce some cool effects :-D
- Jun 19 2008 | 3:08 amWell that's mostly true, but don't confuse perceptual loudness and frequency resolution.Check out the equal loudness curves http://en.wikipedia.org/wiki/Loudness - sensitivity does vary with frequency (as well as many other things) but the dependence is not simple (or logarithmic).Frequency resolution is logarithmic however. The critical bandwidth of the human cochlea is something like a minor 3rd as far as I remember, and of course the number of Hz that a minor 3rd spans grows exponentially with frequency.G'luck with the vocoding!Aengus.
- Jun 19 2008 | 3:28 pmQuote: aengus wrote on Wed, 18 June 2008 21:08----------------------------------------------------> Frequency resolution is logarithmic however. The critical bandwidth of the human cochlea is something like a minor 3rd as far as I remember, and of course the number of Hz that a minor 3rd spans grows exponentially with frequency.>----------------------------------------------------I guess that is the question, how do you calculate the positionof all these "minor 3rds". That would be a very useful thing toknow.
- Jun 19 2008 | 4:13 pmOn Jun 19, 2008, at 8:28 AM, Anthony Palomba wrote:> I guess that is the question, how do you calculate the position> of all these "minor 3rds". That would be a very useful thing to> know.mtof or mtof~ are probably the most direct way in Max.-CChris Muircbm@well.com
- Jun 19 2008 | 4:29 pmKyle Kaplan schrieb:> Hello, I am trying to build a vocoder and was wondering how I might> divide the frequency spectrum up according to its loudness as opposed> to frequency? For instance, if I wanted 8 bands in my vocoder, is> there an equation I can use to determine the best possible frequency> spectrum for each band?In the end this is a matter of taste, but definitely look into mtof,thinking of midi notes as range is more the way we hear. You probablywant equal intervals as bandwidth...Stefan--Stefan Tiedje------------x---------_____-----------|----------------(_|_ ----|-----|-----()--------- _|_)----|-----()------------------------()--------www.ccmix.com
- Jun 19 2008 | 5:33 pmthanks for the advice, hadn't thought of using mtof but now that you mention it, it makes perfect sense.
- Jun 19 2008 | 8:10 pmI'd also look at the frequency ranges traditionally used for vocodersand other effects like the Moog MuRF. You probably don't want todivide the spectrum evenly if you're going for a warm analog sound.The high end probably matters less than the low end. You might alsoconsider a shelf filter on either the low or high ends.The Moog MuRF uses:200. 300. 450. 675. 1000. 1500. 2200. 3400.(100 150 225 325 500 700 1200 Hz differences)Peter McCulloch
- Jun 20 2008 | 1:32 pmA tempered minor third is the frequency ratio sqrt(sqrt(2)), ie pow(2, 0.25). A tempered major third is pow(2, 0.333333).Analog vocoders only approximated third-octave divisions, and I don't suppose for a moment that the cut-off frequencies on a Moog were cent-accurate.You can either use some hard-coded numbers, or do the math. It's not hard if you got past logarithms in high school.-- P.
- Jun 20 2008 | 5:09 pmThe Moog ratios worked quite well. In the spirit of 'sharing is fun' here's my super simple 8-band vocoder for anyone who's interested. wasn't really sure on the Q, so I set it to something that sounded OK and attached some flonum boxes for personal adjustment.
- Oct 08 2016 | 1:42 pmhello im very interested in playing with ur vocoder, but somehow cant see the patch...