What is the earliest source for the prohibition to listen to music during the 3 weeks? Is there any dispute as to the timeframe of the prohibition (only 9 days, week of etc.)?
I just learned a gemara (taanit 30a) that seems to pretty clearly state that the mourning for tisha b'av starts the beginning of the week that tisha b'av falls out on, and ends with tisha b'av itself. ...