The solution is to apply a short fade-in / fade-out. For example, you won't hear a click when a burst of white noise stops. You might not hear it with the other waveforms (square) because they already have high frequency content that will cover part of it (frequency masking phenomenon). You hear the click clearly with the sine wave because the tone has very few harmonics (ideally: none). I know a few audio editors that dynamically apply a short fade (say 32 samples) at the boundary of each audio clip during mixing during playback. Note also that if the tone is contained within a clip in an audio editor, a short fade-in/fade-out might be added automatically by it, attenuating the problem. The "click" is caused by the discontinuity in the waveform and its derivatives - even if the waveform stops at a zero-crossing you might still hear a pop if there's a discontinuity in the higher order derivatives! Its loudness depends on the amplitude at the discontinuity - and it is thus influenced by the length/frequency/phase of the sinusoidal tone. In any case, even if I could find a way to reduce the volume of the square-wave ringtone that the phone did not "normalize away", I still would prefer a pop-free version of the sinusoidal-wave ringtone. What's surprising to me is that the ringtone made with the sinusoidal wave (the one with the slight "pops" at the beginning of each beep) sounds considerably less loud than the ringtones made with the square wave. I figure that the phone probably normalizes the ringtone's loudness somehow. I tried to adjust the loudness of the beep by lowering the amplitude of the wave generated by Audacity, and in fact, when Audacity plays this reduced-amplitude wave it indeed sounds quieter, but when it is saved as a ringtone in my phone, the phone plays both versions of the square-wave ringtone equally loudly. If I pick the square wave + no aliasing option (which, to my ear sounds a little "cleaner" than the option with aliasing, for some reason), the resulting ringtone does not have the "pop" at the beginning of each beep, but it sounds very harsh and loud. I've heard many ringtones of this sort that are crisp, pleasant-sounding, and pop-free, so there must be a way to get rid of these pops.
So I tried fading the sound in and out, which does get rid of the pop, but, as one would expect, makes the beeps sound less crisp. I figure that the pops are an artifact of the discontinuity of the wave at the beginning of each beep (though, curiously, I don't hear a pop at the end of each beep). I've tried to get rid of those pops, with little success. If I pick the sinusoidal option when constructing the profile above, and export it as a WAV file, when I play the ringtone in my phone, I can hear a slight "pop" at the beginning of each beep. and Generate > Tone.), and one even has a choice of wave shapes (sinusoidal, square, etc.). With Audacity, it's relatively simple to generate this profile (with Generate > Silence. This profile results in a very standard beep-beep ringtone. By "pure tone" I mean something like a sinusoidal or square wave with a fixed frequency (let's say 350Hz for concreteness). I'm trying to make a super simple ringtone: 0.5s silence + 1s "pure tone" + 0.5s silence + 1s "pure tone" + 0.5s silence.
I hope this ultra-noob question is not entirely out of place here.
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