Is there a way to keyframe the volume of a sound track attached to a prop?

I have a scene with a character sitting at a table in a room. I have an MP3 file attached to the room as a sound track. I want the sound track volume to start at one level, but when my character starts to speak I want to lower the volume of the sound track without turning it off. I haven't been able to figure out how to do this. Can the volume of a sound track be keyframed?

TIA