Although in the second instrument we could control and vary the overall amplitude from note to note, it would be more musical if we could contour the loudness during the course of each note. To do this we'll need to employ an additional unit generator linen, which the Csound reference manual defines as follows:
kr linen kamp, irise, idur, idec ar linen xamp, irise, idur, idec
linen is a signal modifier, capable of computing its output at either control or audio rates. Since we plan to use it to modify the amplitude envelope of the oscillator, we'll choose the latter version. Three of linen's arguments expect i-rate variables. The fourth expects in one instance a k-rate variable (or anything slower), and in the other an x-variable (meaning a-rate or anything slower). Our linen we will get its amp from p4.
The output of the linen (k1) is patched into the kamp argument of an oscil. This applies an envelope to the oscil. The orchestra and score files now appear as:
instr 3 k1 linen p4, p6, p3, p7 ; p4=amp a1 oscil k1, p5, 1 ; p5=freq out a1 ; p6=attack time endin ; p7=release time f1 0 4096 10 1 ; sine wave ;instr start duration amp(p4) freq(p5) attack(p6) release(p7) i3 0 1 10000 440 .05 .7 i3 1.5 1 10000 440 .9 .1 i3 3 1 5000 880 .02 .99 i3 4.5 1 5000 880 .7 .01 i3 6 2 20000 220 .5 .5 e