Every once in a while I completely lose it… the feel for my serve, that is. I strongly suspect that he primary root cause when that happens is a loss of racquet head speed. A few weeks ago I started experimenting with an inexpensive device that provides audio feedback on that very thing.
The Whistler looks like a string vibration dampener. However, instead of performing that function it is essentially a hard plastic whistle. If the racquet head speed is sufficient, a high pitched sound will be produced. If no sound results, well… there’s yer problem.
The manufacturer recommends placing the Whistler at the top of the strings for maximum efficiency. That checks out with the physics of angular momentum as the perceived velocity of the racquet head will be faster at the top of the racquet than if it was placed in the traditional location of a string dampener near the bottom of the frame.
In my field test of the device, I found that most of my strokes easily produced the appropriate sound. In my own personal rendition of the Hawthorne effect, that included my serve. Racquet head speed turns out to not be my problem, but paradoxically only if I am aware that it is being measured.
I doubt that the device is strictly legal for sanctioned play. The sound that it emits could constitute “coaching” or also be a hindrance. However, I keep it in my bag and will likely pop it in from time to time just to verify that my swing path is consistent with my expectations.
The maximum benefit of the Whistler is likely centered around people that are new to tennis. More experienced players can also derive benefit from the feedback. At the price point, the device is so inexpensive that it easily exceeds my cost to benefit criteria.
 | The Whistler from Oncourt Offcourt |
