Long Tail Theory
When we hear sounds, our auditory system uses an averaging system to determine relative loudness. The averaging ‘window’ can be as long as a second. Tests have shown that up to this point, noise bursts of constant sound pressure level but increasing duration appear to get progressively louder. Rhythmic material is particularly suited to making use of this psychoacoustic effect given the short duration of all but the most bombastic orchestral percussion.
Here we’re sticking to hi-hats once again, but this time we’re varying their decay. The hi-hats from before have been bounced to an audio track, sliced and edited:
Again, a more complex pattern of hat length/decay makes for a varying and interesting groove:
Applying small pitch variations can also be used to add interest to a simple drum pattern. However, in this case, there is somewhat of a conflict going on. Pitching a sampled sound higher usually involves playing it back faster. Faster playback means a shorter duration, and therefore a lower perceived loudness. At the same time, it has an enhanced high frequency content, often interpreted as a nearer source. Here’s the effect when every other sample is higher:
And again a more complex example:
This effect obviously doesn’t work exactly the same in all cases. Analogue drum machines are a case in point, where pitch and amplitude envelope are not intrinsically connected.