Why Olympians should study phonetics

« previous post | next post »

There isn't much connection between the Olympics and linguistics, but I feel compelled to point out that something that has been in the news would not be news to anyone who had studied acoustic phonetics. I refer to reports of a study showing that sprinters closer to the starting gun get off sooner than those farther away, giving them an advantage in the race.

Sprint lanes are 1.25 meters wide, so the runner in the Kth lane is (K-1) * 1.25 meters farther from the starting gun than the runner in the first lane if the starter is in line with the runners. If you had studied acoustic phonetics, you would know that the speed of sound in air is approximately 340 meters per second. That means that it takes ((K-1) * 1.25)/340 seconds longer for the sound to arrive. Here is a table showing the delay in milliseconds with respect to the leftmost runner.

Lane Delay (ms)
2 7
3 11
4 15
5 18
6 22

These values may seem small, but at the Olympic level races are often decided by one one-hundredth of a second (10 milliseconds), so they are significant.

If the starter is not in line with the runners, the exact values are different, depending on his or her position, but the runners nonetheless hear the gun at different times with roughly similar differences in timing.

Incidentally, I understand that in swimming the starting gun is reproduced by a loud-speaker behind each starting block so that the swimmers all hear it simultaneously. I don't know why this intelligent arrangement is used in swimming but not in track.

P.S. Yes, the speed of sound will be on the exam.



24 Comments

  1. James A. Crippen said,

    August 12, 2008 @ 1:30 am

    Don't false starts indicate that runners are often not listening to the starting gun, but are instead relying on visual cues?

  2. Rubrick said,

    August 12, 2008 @ 1:38 am

    If I were to guess why the loudspeaker technique is used in swimming but not in track, it's tha it's easy to install loudspeakers permanently or semi-permanently outside a swimming pool, but for track they'd have to be portable to get them out of the way for other events.

  3. Harry said,

    August 12, 2008 @ 2:07 am

    There was something about this in New Scientist a few weeks ago. From memory, it is used on the track in most athletics events; there are loudspeakers in the starting blocks. And the loudspeakers are in place at the Olympics as well, but for reasons of tradition they trigger it with a starting gun, so there's both a bang from the gun and a noise from the blocks. But the reaction times of the athletes closest to the gun are still faster.

  4. Timothy M said,

    August 12, 2008 @ 3:34 am

    Sounds more like acoustics than phonetics to me….

  5. Giovanni said,

    August 12, 2008 @ 5:54 am

    It looks like the table is incorrect, the difference between lane 1 and lane 2 is 3,67ms. You applied the formula with K instead of K-1.

  6. Rob Gunningham said,

    August 12, 2008 @ 6:28 am

    So false starts indicate they're just trying to get their feet off the loudspeakers.

  7. RPM said,

    August 12, 2008 @ 6:42 am

    Um, I think speakers are used in track: http://entertainment.howstuffworks.com/olympic-timing2.htm

  8. MattF said,

    August 12, 2008 @ 6:49 am

    Hmm. But– being contrary about this– doesn't the gun set off a shock wave, which would be traveling faster than the speed of sound in air? Maybe that's why you use a gun…

  9. andy said,

    August 12, 2008 @ 7:16 am

    The gun is mostly for show, it's usually electronically wired to both the timing and speakers behind the runners. The speakers being movable so they can be removed.
    This is usually no problem as the starting blocks will have to be removed anyway (longer races come back round remember).

    With regards to the swimming example, I wonder if the effect of firing a gun inside a swimming hall might factor in…

  10. Faldone said,

    August 12, 2008 @ 8:01 am

    The news reports I've read on this all seemed to say that it was the decreasing sound level as you got farther from the source that caused the increased reaction time. The only numbers I saw were numbers listing reaction time in lane 1 and the average of all the other lanes. Another classic example of the worthlessness of news articles on scientific findings, but if the volume of the sound has a contributory effect it just makes matters worse. I had thought that the speed of sound may be a factor in this but hadn't run the numbers myself. Thanks for those figures.

  11. Martin said,

    August 12, 2008 @ 8:36 am

    Assuming that for some reason they can't use loudspeakers, wouldn't it make sense for the starter to stand centrally behind the runners, to halve the maximum difference between delays?

  12. Johan Richter said,

    August 12, 2008 @ 8:45 am

    Yeah, I've heard they use they use it in track as well. And it is reasonable that they should, since the speed of sound is very well known fact, and not just among people who have studied phonetics.

    Here (http://www.ualberta.ca/~dcollins/Posters/Scapps2005.pdf) is a poster from the same research group with a preliminary version of the results. They are clearly talking about the intensity of the sound, not its time of arrival. So the reporting seems to be correct in this instance.

  13. ed said,

    August 12, 2008 @ 9:25 am

    The speakers are used in swimming because swimmers are much smarter than runners.

  14. Stephen said,

    August 12, 2008 @ 10:25 am

    Volume may have something to do with it. Closer means louder, and louder might trigger an autonomic response to run, like when one hears a loud noise and jumps or screams.

  15. mollymooly said,

    August 12, 2008 @ 11:01 am

    Here's an article from 2005: http://www.trackandfieldnews.com/features/2005/start-problem.html.
    Executive summary:
    loudspeaker relay of the gun has been used since the 1970s. this does not seem to work better than no loudspeaker. Since the 1990s, some meets use a fake gun with loudspeakers simulating a real gun. This does work.

    Another issue is whether the mark-set-go sequence is automated and with standardised intervals (in which case you can train to practice for the perfect "reaction" timing) or at the discretion of the starter (in which case not)

  16. Chris said,

    August 12, 2008 @ 11:50 am

    It's been ten years since I took my required phonetics course, but I seem to recall that acoustic difference less than 30ms are not perceptible (or are not predictably perceptible, something like that). Is my memory bad here?

  17. Johan Richter said,

    August 12, 2008 @ 1:52 pm

    If the sound reaches you 30 ms later you are obvisiously going to react 30 ms later, all else being equal.

  18. john riemann soong said,

    August 12, 2008 @ 2:57 pm

    But that's with an extra phonetic processing layer on top isn't it? The appearance of speechlike patterns can influence perception, but doesn't that come after the signal has been fed into the auditory cortex?

  19. Tristan McLeay said,

    August 13, 2008 @ 10:56 pm

    Chris and Soong, my understanding of the perception issue with 20 ms (which is the value I know — maybe I remember it wrong?) is that things which happen less than 20 ms apart are perceived as occurring at the same time. This doesn't just affect sound processing, but visual and other perceptions, so that if you have one light turn on 10 ms after the other, they're likely to be described as occurring at the same time.

    Quite what the basis for this is I'm not sure, but even if it is that our brains operate on a fixed 20 ms cycle time, so that they can only process new information in batches 20 ms apart, much like a computer screen, then there's no reason to believe everyone's synchronised, much like a video camera recording a screen and you can see the screen flickering really badly. If that analogy makes any sense to anyone but me.

    But as Johan Richter rightly points out, if you're not trying to determine whether two events are happening at the same time, but you're simply reacting to a single event — well, it doesn't matter. If someone's reaction time is 1 s after an event happens, and it takes 20 ms for event to reach them, they will react 1.020 s after the event. If it only takes 2 ms for the event to reach them, they will react 1.002 s after the event.

  20. Max R said,

    August 14, 2008 @ 5:15 am

    MattF: that shock wave *is* the sound. A supersonic bullet might cause a supersonic boom, which would be an additional effect, but live ammunition is not encouraged at sporting events.

  21. Michael Le Page said,

    August 14, 2008 @ 1:21 pm

    Here's a link to the New Scientist article mentioned by Harry.

    Basically, the issue is more complicated than just the delay in sound reaching inner lanes – the loudness of the gun also matters, because louder sounds produce a stronger reaction.

    So the fair way to do things is to have a silent gun and the sound coming only from loudspeakers behind each athlete. That's not what they're doing in the Olympics.

    http://www.newscientist.com/channel/being-human/dn14183-olympic-start-gun-gives-inside-runners-an-edge-.html

  22. Matt said,

    August 15, 2008 @ 12:58 am

    When I ran track in high school, we were taught to "go" on the smoke coming out of the gun, not the sound itself. Presumably this doesn't help much for the 4x100m or the 200m (where looking directly at the starter might not be practical, due to the curve of the track) but it seems like it should even things out for everybody else.

  23. Johan Richter said,

    August 18, 2008 @ 7:09 am

    I think the blog post should be updated, the research finding clearly isn't about the speed of sound and they already use loudspeakers behind every runner.

    The issue is that the runners closer to the gun hear a louder noise, since they hear it from both the gun and the loudspeaker. And the claim is that a louder noise makes decreases the reaction time.

  24. 020304 said,

    September 25, 2012 @ 9:01 pm

    343 m/s

RSS feed for comments on this post