Smart Tempo is the name for the suite of tools in Logic Pro X that handle automatic tempo and analysis, plus of course you have a great deal of control over how tempo is altered, should you wish to use it. In this short video from the course Logic Pro X 301: Smart Tempo Demystified, Joe Albano explains the concepts and theories behind tempo manipulation, and how they work in Logic Pro X.
Joe explains that not all that long ago, DAWs could not alter the tempo of digital audio without also affecting its pitch. This resulted in the classic sped-up or slowed-down effects that could be heard in many productions in the 1980s and 1990s. Now, DAWs like Logic Pro use complex algorithms to analyse and process sections of waveforms, the net result of which is that audio can be made as flexible as MIDI.
This technology leads to even more advanced capabilities. Not only can audio be time stretched using Smart Tempo without affecting its pitch, but it can actually follow tempo maps, changing speed gradually while the pitch remains unaffected. Just a decade or two ago this would have seemed like a magical process, but now it's available right inside Logic! For much more on using Smart Tempo, be sure to check out the full course using the links below and take advantage of the power of Logic Pro X.