[bp~ 100 0.5]which has its center frequency controlled by the MIDI note frequency.
[/127]gives us a normalised value from zero to one. The combination of
[-]is an idiom that inverts a normalised signal, so that it ranges from one down to zero as the input increases. A
[swap]object exchanges its inputs, so when used with
[-]we get 1 minus x for an input x.
[line~], activated by a message producing a variable decay envelope. The decay range is substituted in
$1, a value ranging between zero and 400 milliseconds. Notice the second part of a message to
[line~]can be omitted when it's a zero in the first position. Where we use $1, $2 etc9 in a message box, each is replaced by the value of any corresponding list element that appears at the message box inlet. In this case a float in the range 0 to 400 will replace $1 in the list so it becomes something like
[1, 0 390(, the MIDI note now controls the decay time.
[lop~]final stage, and then boost it back to reasonable level.
[lop~]is a simple low pass element with one parameter for its cutoff frequency.