Sine, square, triangle, and sawtooth waveforms

[Tricky-Loops]

The difference I can ear is the "harshness" of the sound...square and sawtooth aren't so smooth as sine and triangle.
I guess a litle bit of training is needed to recognize them.

You should be able to differentiate between them by noticing the amount of harmonics. A simple sine only consists of the fundamental (tone) whilst a super-saw has the highest amount of harmonics and overtones. And the square is between sine and saw, it has some "hollow" woodwind-like sound...

[Sendy]

In practice what makes a developer to decide to use a Sine, square, triangle, or sawtooth waveforms?

I have heard some examples os these waves and I can't ear any difference.

Thanks

For a start you need to use *some* kind of periodic waveform to produce a tonal sound. These waves are the most obvious from an electronical point of view, and hence have become a cornerstone of synthesis.

The sawtooth wave contains all even and odd harmonics and they fall off in the treble range at a rate which produces a bright sound that isn't too harsh on the ears. You can think of the sawtooth as an idealized representation of a string being displaced gradually by a bow (the slope of the waveform) and then snapping back into position (the vertical drop).

The square wave contains all odd harmonics which makes it distinct from the sawtooth wave, and can be thought of as an idealized representation of the movement of air in a resonating column. It sounds "hollow" and conjures up the idea of space. It's also cheap to produce electronics-wise, so appeared in a lot of cheap toy devices and video games.

The triangle wave is a "cheap sine wave" in that it's a piecewise simplification of it, and sounds very much like a muffled square wave. Waveforms like the sine and triangle which do not feature vertical or near-vertical jumps are always softer sounds and the triangle is ubiquitous for flute-like leads, gentle pads and soft basses.

It's said in many synthesis articles that the choice of waveform is the most important deciding factor on how a patch will sound, but as much as I fetishize waveforms, I've found this not to be true a lot of the time, the filter and amp envelopes contribute the most to a sound in my opinion. If you take a short "pluck" amp envelope you can play it with pretty much any waveform and people will tell you it reminds them of a banjo.

As a final note I'd like to point out that being given a palette of these basic waveforms doesn't restrict you as much as one may think, as on a decent synth you can make one waveform alter the shape of another one or use countless other tricks to create new waveforms from old, and that's before you've even got to the filter.