A bending of sound waves when passing obliquely from one medium to another in which the velocity of sound is different.
"I was completely blown away by the quality of the work you performed on these very old (70+ years), home-made 78rpm records. I had not tried to even play the records for decades because the last time I tried it was impossible to hear much of anything but the scratches. I realize that a couple of them were not able to be fully restored - that ..."
