This assignment is to build a polyphonic FM instrument, using the phase modulation formulation of FM synthesis (see 2.10c.frequency-modulation.pd in the class examples).

To make it simple, use the same frequency for the carrier and modulator (the phasor~ and the osc~ in the patch), and make a single envelope that you will use (scaled differently) for both the output amplitude and for the index of modulation. The envelope should look like this:

Your successful patch should be able to make sounds like this.

To make the patch:

• Once more make a main patch and a "voice" abstraction, and have the main patch include 8 copies of the abstraction. Make a voice selector to distribute pitches to the voices using the same mechanism as in homework 4. (You won't need to use any "$" arguments for this example).
• Inside the abstraction put objects to do phase modulation. The pitch of both of the oscillators can come from the inlet. When a pitch arrives at the inlet you should also set in motion a line~ using the timing and values shown above.
• Use a multiplier to scale the line~ output so that its maximum value is 0.25 (one quarter). Use that scaled value to control the index of modulation.
• Square the output of the same line~ object and use that value to control amplitude.
• You should be able to test this by simply connecting a number box to the input of the voice selection step. You can make a sequencer if you want, or simply use a random number generator to generate pitches in a reasonable range (60 to 90, say). The sequence of pitches in the soundfile I made was (60 62 65 67 70 72 74 77) separated by 200 milliseconds each.

Make the usual output level control and some way (clearly labeled) to make the patch play notes (either a number box or something automatic as described above), and make a zip archive of the main patch and the abstraction together in a directory as usual.

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