Why there is a click sound when I play a sound?

Question

When I consider this simple code:

ListPlay[RandomReal[1, {2000}], SampleRate -> 1000]

I hear a click at the beginning of the sound sample and at the end of the sound sample. When I play couple of notes, click sound can be heard easier between notes.

a = Play[Sin[440 2^(1/12)  4 π x], {x, 0, 0.5}];
b = Play[Sin[440 2^(1/6) 4 π x], {x, 0, 0.5}];
c = Play[Sin[440 2^(1/4) 4 π x], {x, 0, 0.5}];
Sound[{a, b, c}]

Can that click sound be eliminated? Why does that happen?

I hear the same click sound when I play the sound at different laptops.

Answer 1

You can remove the clicks by fading the sound in and fading it out. One possibility is:

a = Play[CosineWindow[x - 0.5, 0.4] Sin[440 2^(1/12) 4 π x], {x, 0, 1}];
b = Play[CosineWindow[x - 0.5, 0.4] Sin[440 2^(1/6) 4 π x], {x, 0, 1}];
c = Play[CosineWindow[x - 0.5, 0.4] Sin[440 2^(1/4) 4 π x], {x, 0, 1}];
Sound[{a, b, c}]

Now the transitions are smooth. You can play with the coefficient (0.4 above) to adjust the duration of the fades or use other windowing functions.