Speech Perception Problems

A colleague of mine and I were talking on the phone, and he happened to mention somebody by the name of Sassoon (This guy? The subject quickly changed), but I was unable to understand him. He repeated himself a couple of times, but it wasn't until he spelled it out that I was able to know what he meant. Now, we were on the phone, but I had no other difficulty understanding him, and as he pointed out, 8-bits should be plenty for me to understand. Occasionally there is ther other miscommunication here or there, where it is strong like this, but there's nothing in common from the few examples I can remember. In the interest of discovering why my otherwise excellent speech perception is failing, I'm going to begin to index these. Any theories?