Interesting factoid: the human brain processes sound faster that sight [1]. The difference cited in the paper below is roughly 40 ms, which is small in an absolute sense, but compared to the relative time tolerances we are discussing here in this parent article, it's huge!
Naturally this effect cancels out if all competitors get the same visual cue, however it's still to the benefit of athletes and fans to want quicker reaction times:
- Shorter overall reaction times means faster races means better records
- The standard deviation of reaction times is smaller for sound than for sight, which means the reaction time is more fair to all
Vision is amazingly sluggish. Turning an incoming photon into a nerve impulse involves a whole mess of slow (and fascinating) chemistry, just to leave the rod or code. Once it does that, the resulting signal bounces around the retina and then a huge portion of the brain before it's available for "action."
The auditory system, on the other hand, is optimized for speed. It has a giant synapse (=connections between cells), called the Calyx of Held, that is specialized for extremely fast (sub-millisecond), reliable transmission between cells. They're really cool looking: https://www.eurekalert.org/multimedia/pub/213595.php?from=44...
At least some swim meets use a light and a buzzer. I first encountered that many years ago at Gallaudet, a school for the deaf. I think that has become common at all swim races. It certainly makes sense to not exclude racers who can't hear.
I did note at the time that the gunshot sound put an extra oomph into the start over a buzzer. No idea whether that actually made a difference to my time, but it sure got my heart rate up.
When I ran cross country in high school our coach always said to go on the sight of the smoke not the sound of the shot. This was when the starter was in front of the whole mass of runners. Not sure if it ever helped me given we were mass starting a race that lasted for 3ish miles.
If you were by yourself, that would only shave a fraction of a second off your 5k time. However, getting out in front of a big mass start also helps you avoid getting caught in "traffic", which can really bog you down.
My father was a world-class competitive swimmer and is a Deaf man. His stories about needing to rely on a visual cue when his hearing competitors benefited from the pistol sound were always fun -- as is the joy on his face when he narrates that he always beat them anyways.
Sprinters, for whom small margins make the biggest difference, are most often not looking at the starter. Granted, could be because they don't have to because someone is firing a .32 caliber blank nearby, but that horse has left the barn for now.
