Audio Toolbox for Mac

Using no additional hardware, you can produce sine, square, triangle, and sawtooth waveforms of any frequency up to 22 kHz, as well as generate noise - both pink and white. Mac Audio Toolbox can be used to create all sorts of cool sound effects. You have full control over the frequency, type and volume of each sound produced.

You can generate up to 13 different waveforms. Each waveform can be routed to either the left or right channel, or to both. The amplitude of each waveform may be adjusted, as well as the volume on each channel, which is a mix of any waveforms routed to that channel. The settings of all 13 waveforms can be controlled via AppleScript. In addition, there is a sweep generator. Super for producing "Whoop Whoop" sounds, sirens, and more.

You can also save the audio you create to an AIFF file for further use, or for burning on a CD. There is also a spectrum display (Mac OS X only) that allows you to look at which frequencies are present in an audio signal, using FFT. There is also an oscilloscope display (Mac OS X only) that allows you to look at the input waveforms for both left and right channels.