<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Katja, that sounds like a nice approach. With sound file playback, I could just delwrite~ the audio 3 seconds so everything would resync. I'm going to have to go back and look at fft, again. I spent a lot of time figuring out how to use [fft~] a few years ago. I'm not quite clear on how to tell what Hz value each bin is indicating. Wait, is it as simple as sample-rate/block-size=Hz?</div><div><br></div><div>By the way, if I was starting at the beginning with [fft~] this is the place I would go to start figuring it out:</div><div><a href="http://www.pd-tutorial.com/english/ch03s08.html">http://www.pd-tutorial.com/english/ch03s08.html</a></div><div>Many thanks to Johannes Kreidler for these excellent and thorough guides. It's an excellent place to discover new things, even for experienced users.</div><div><br></div><div>Sam</div><div><br></div><div><br></div><div><br></div><div><br></div><div><br><blockquote type="cite"><div><br>------------------------------<br><br>Message: 7<br>Date: Mon, 17 Oct 2011 23:43:45 +0200<br>From: katja <<a href="mailto:katjavetter@gmail.com">katjavetter@gmail.com</a>><br>Subject: Re: [PD] Analyzing subharmonic frequencies accurately<br>To: <a href="mailto:pd-list@iem.at">pd-list@iem.at</a><br>Message-ID:<br><span class="Apple-tab-span" style="white-space:pre"> </span><<a href="mailto:CAFY0eaozjc=xMoq3h2mJo6XmAhtKz-V1+XfM44ps4s+ZMb=12A@mail.gmail.com">CAFY0eaozjc=xMoq3h2mJo6XmAhtKz-V1+XfM44ps4s+ZMb=12A@mail.gmail.com</a>><br>Content-Type: text/plain; charset=ISO-8859-1<br><br>Hi,<br><br>With fft~ you can go up to a framesize of 2^17, that is around 3<br>seconds when assuming 44.1KHz SR. The bin resolution is then ~0.37 Hz<br>which may be just accurate enough for your purpose (spectral leakage<br>will always make analysis less precise than the bin resolution<br>suggests). Notice that the latency of your info will also be 3 seconds<br>then.<br><br>Katja<br><br><br><br>On Mon, Oct 17, 2011 at 11:24 PM, Samuel Burt<br><<a href="mailto:composer.samuel.burt@gmail.com">composer.samuel.burt@gmail.com</a>> wrote:<br><blockquote type="cite">A friend of mine asked me if I could make some kind of filter that could provide information about subharmonic frequencies. I wasn't quite sure what he meant, but I thought I'd try a few things to see what I could get.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">He mentioned he wanted the following bands 1-3 Hz, 4-6 Hz, 7-9 Hz, 11-14 Hz, and 15-18 Hz.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">The first thing I tried was a series of [lop~] and [hip~] filters in the ranges he was wanting. I stacked multiple [lop~]s and [hip~]s, to make really hard limits and then sent the output from each band to vu~ meters. This was unreliable. In fact, a 5 Hz sine wave seemed more likely to show up in the 10 Hz band. I also tried [bp~], [vcf~], and [svf~] with no luck.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I then took a different approach, using [threshhold~] and [timer] to time the distance between zero crossings and output the result. This is very reliable for a sine wave, but I fear it wouldn't be that useful for real world signals.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Have any of you ever tried to separate out subharmonic frequencies in Pd? Any experience with brain wave analysis in software? What's a better technique?<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Thanks,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Sam in Baltimore<br></blockquote><blockquote type="cite">_______________________________________________<br></blockquote><blockquote type="cite"><a href="mailto:Pd-list@iem.at">Pd-list@iem.at</a> mailing list<br></blockquote><blockquote type="cite">UNSUBSCRIBE and account-management -> <a href="http://lists.puredata.info/listinfo/pd-list">http://lists.puredata.info/listinfo/pd-list</a><br></blockquote><blockquote type="cite"><br></blockquote><br><br></div></blockquote></div><br></body></html>