RealBeat is a sampler software that lets you record, cut, loop and make beats out of these sounds.
You can record the noise of your fan, your car - or you can let your Mac speak for itself with its built in text to voice feature. You can then use these real sounds as basic elements of your loop and create interesting and unique rhythms out of them.
Its a straightforward app that does not have excessive tweaking capabilities and cluttered screens, instead it makes everything easy to inspire creativity. You can also export the created tracks as songs.
Other features include a built in sequencer, audio effects like distortion, reverse and pitch controls, pattern editing and sound resampling.