I've been asked about the Sonic Golf Training Aid that has been developed by Yale Professor Dr. Robert Grober. I've yet to try it, but here's a video going over it.
It's definitely an interesting concept. The main issues I have with it are:
1) You have to find an old club and re-grip it with the Sonic Golf grip.
2) It's not cheap ($399) -- although I can see how they justify the price with that type of technology.
3) I've been told it teaches a pause at the top of the swing. The video doesn't seem make the 'pause' that pronounced, so some of the people that have tried it may be exagerrating the type of pause Grober is actually talking about.
Still, this appears to be a real nice product because it attacks in my mind a major issue with golfers in a very fast startdown instead of being slow and deliberate on the startdown and then getting all your speed at impact.
What I like about the Taly training aid device is that it helps rid the golfer of having too fast of a startdown visually. Sonic Golf helps those with fast start downs by teaching them through sound.
You can find this training aid at www.sonicgolf.com.