I am using a micro SC card reader to play wav files using the tmrpcm library. I would love to make an LED blink in time with a voice talking, but I can't figure out how.
If you're outputting the audio via a speaker, can't you wire a LED in-line with the speaker using a transistor? Depending on the setup, you might not even need the transistor, and could wire the LED directly in-line between the output and speaker.
Honestly, I never thought of that. I will need to see how it affects the audio quality and volume, but it may not be a bad idea 
I will need to find a way to have a switch that keeps the LED from blinking with every sound effect and only work with the voice sound clips.