That's what "bear bells" are for...in bear country.

Mountain lions are avoidant at all times unless it's a mother with cubs and even then they'll let you know well in advance.

Otherwise, just normal conversation, your smell with even a light breeze, and the vibrations on-trail will alert all animals to your presence.

In other words, the "trail music" theory is bullshit. They just want to listen to their music.