Waveforms
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Basic Audio Wave Shapes
The most important characteristic of sound that have a definite pitch is that they have a repeating waveform. With audio oscillators we can generate what are considered to be the 4 basic waveforms, the sine, triangle, square, and sawtooth (or "ramp") waves. These waveforms, in that order, represent a steadily increasing complexity of shape and of timbre as the number and strength of the harmonics for each wave form increases.
For each of the following waveforms, I have provided a 10-second audio sample of the wave played at a frequency of 110-Hz and a level of -18dBFS
Sine Wave
Sounds like the lowest of the samples because it is only playing the fundamental frequency or "pure tone" of 110-Hz.
Triangle Wave
Sounds somewhat higher, richer, and a bit louder because the fundamental frequency is joined by the odd harmonics which are those frequencies 3x, 5x, 7x, etc. above the fundamental, in this case 330-Hz, 550-Hz, 770-Hz, etc.
Square Wave
Sounds higher, richer, and a bit louder still. It is similar to the triangle wave in that only odd harmonics are present, however the harmonics are louder relative to the fundamental frequency and so have a greater impact on the timbre of the wave.
Sawtooth Wave
Also called a "ramp" wave for obvious reasons is the most complex of the basic wave shapes. You can view it as the 'front end' of a triangle wave and the 'back end' of a square wave. The more complicated shape generates more overtones, in this case every harmonic is present at gradually decreasing levels.
References
Jeremy Krug's writings on Waveforms
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