a sound for sore ears
What you happily describe someone's voice as when you've been trying to reach him on the phone for a while; it's the "auditory equivalent" of what you say when you finally meet up with someone whom you've either been worried about, been waiting anxiously for, or haven't seen for a good while.
After many tries, I was finally able to speak to my buddy on da horn after his having been repeatedly in and out of da house over da past week to run some urgent/unexpected errands; his cheery and slightly-apologetic voice sure was a sound for sore ears!