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.

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