01_01_1B
additional parameters: if1, if2

This run plays the "Manhattan blues on tape M1485" with a sound
reminiscent of an electric piano.

(score of Manhattan Blues fragment)

The design is a subtle variation of 01_01_1, with both envelope
and wave controllable on a per note level. Note that the tempo
statement alters the meaning of durations in the score file. The
envelope varies with duration and the harmonic richness with
pitch. This means that we distinguish four kind of notes:

1) brief and low (<.2 sec, <250 Hz)
The function f31 will give a sharp attack. While the first two
decay fragments approximate an exponential shape, the third tries
to imitate the effect of a damper. The waveform has ten
harmonics.

2) brief and high (<.2 sec, >250 Hz) 
The same envelope f31, but now coupled with a waveform with only
seven harmonics.

3) long and low (>.2 sec, <250Hz)

Exponential envelope f51 teams up with a 10 harmonics wave. The
envelope minimum of 2(**-6)=1/64 produces 6/10 of "reverberation
time" (time for the level to drop to 60 db). The durations of the
longer notes range typically  from .4 to .8 sec. Compared to a
real piano (1s at 2000 Hz, up to 10s at 200 Hz), the
reverberation times are somewhat shorter here. On the other hand,
the discrepancy is lessened by the fact that the initial decay
rate in a real piano is higher.

4) long and high (>.2 sec, >250 Hz)

The last option is covered by the exponential envelope f51 and a
7 harmonics wave. (Risset 1969: #301)
                             
(illustration 2 different types of envelopes: brief and long notes)

(flowchart)
(.orc and .sco files)

