Use headphones and a microphone. Listen for modulation of the input audio.
<CsoundSynthesizer> <CsOptions> -d -f -m195 -odac -iadc </CsOptions> <CsInstruments> sr = 48000 ksmps = 128 nchnls = 2 nchnls_i = 1 0dbfs = 1 instr 1 prints "Sing or play into the microphone...\n" ainput inch 1 imaximum_delay_milliseconds init 4000 amodulation_hz init 35 amodulation_depth init 0.125 aclip init 0.5 askew init 0.5 kdelay chnget "kdelay" printks2 "kdelay: %9.4f\n", kdelay kmodulation_hz chnget "kmodulation_hz" printks2 "kmodulation_hz: %9.4f\n", kmodulation_hz kmodulation_depth chnget "kmodulation_depth" printks2 "kmodulation_depth: %9.4f\n", kmodulation_depth kclip chnget "kclip" printks2 "kclip: %9.4f\n", kclip kskew chnget "kskew" printks2 "kskew: %9.4f\n", kskew akmodulation_hz = a(kmodulation_hz) akclip = a(kclip) akskew = a(kskew) amodulator squinewave akmodulation_hz, akclip, akskew, 0 amodulator = amodulator * kmodulation_depth + .5 adelay = kdelay + amodulator aoutput vdelay3 ainput, adelay, imaximum_delay_milliseconds printks "ain: %9.4f aout: %9.4f\n", .5, dbamp(rms(ainput)), dbamp(rms(aoutput)) outs ainput, aoutput endin </CsInstruments> <CsScore> i 1 0 3600 </CsScore> </CsoundSynthesizer>