I just recently updated my MBP to Yosemite. So I downloaded the latest version of Adacity and reinstalled the application. But it crashed at start up. (The icon appeared for a second on the dock then disappeared). Help!
Please see the pink panel at the top of the page and give us the three-digit Audacity version number. Make sure you have Audacity 2.1.0 from Audacity ® | Free, open source, cross-platform audio software for multi-track recording and editing..
Also see this FAQ: Audacity Manual.
If you are seeing a message “Audacity could not find a place to store temporary files” please see Audacity 2.0.6 not installing on Mac OS 10.10.2 [SOLVED]