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#X text 363 596 updated for Pd version 0.39;
#X text 119 474 low-pass filter;
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#X text 182 504 graphing on/off;
#X text 407 545 --- 0.02 sec ---;
#X text 43 44 This and the following patches show how to use filters in Pd \, starting with the simplest one: the one-pole low-pass filter. Here we test it with an input of white noise. The lop~ object does the filtering. Its left inlet takes an audio signal to be filtered \, and its right inlet takes messages to set its cutoff frequency in Hertz.;
#X text 41 143 The lop~ object is normalized to pass DC (the lowest frequency) with a gain of one. Higher frequencies are progressively more and more attenuated. The lower the cutoff frequency \, the lower the total power of the filtered noise. If you graph the output you'll see that the waveform gets smoother (and smaller overall) as the cutoff frequency is lowered.;
#X text 43 257 At the cutoff frequency the gain is about -3 dB \, and above that the gain drops a further 6 dB per octave. (Sometimes one uses the word "rolloff" instead of "cutoff" to emphasize the gradual way the gain drops off with frequency.);
#X text 137 371 white noise \, test signal;
#X text 98 19 ONE-POLE LOW-PASS FILTER;
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#X text 47 147 This subpatch loads initial values in number boxes., f 30;
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#X text 160 401 <= cutoff (pitch units);
#X text 163 448 <= cutoff (Hertz);
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