Noticing an audio delay

Hi everyone, I'm new to this forum and this is my first post. I'm hoping someone here can answer a question I have. I found a couple posts on AVS and on other forums about this issue, but I haven't come across a good explanation yet.


Two weeks ago I purchased my first HDTV - a Pioneer PDP-5070HD. It's a fantastic plasma display and many HD programs look simply stunning. I'm currently using an antenna to receive OTA HD broadcasts and I pipe the digital audio to my receiver. I've noticed that there seems to be a slight audio delay on NBC (WOWT) shows. It seems to be almost nonexistent except for on The Tonight Show with Jay Leno and Late Night with Conan O'Brien. It's barely noticeable on Leno, but extremely obvious on Conan. I do not notice an audio delay on any show from any other station. I was wondering if this is a national NBC problem, local NBC affiliate (WOWT) problem or something on my side?