Dance Timing and Rink Acoustics: A Thought Experiment

[Query]

Dance Timing and Rink Acoustics: A Thought Experiment

An interesting question is how ice rink and P.A. system acoustics affects perceived dance timing at the judge's stand.

In particular, the time-of-arrival of the music at the dancer's position in various parts of the rink and the time-of-arrival at the judge's stand could differ by as much as .2 seconds.

(That is an extreme case, in which the speakers are all located at the judge's stand, or at the opposite corner.)

This means that you can be perfectly in sync to the music that you hear, but will appear to be ahead of or behind the music at the judge's stand, depending on your location in the rink.

(It also means that as you traverse the pattern, a metronome you carry won't sync with the music you hear.)

If you wanted to produce a perfect result at the judge's stand, you would have to measure the difference between the time-of-arrival of sound at various parts of the rink surface, to the time-of-arrival at the judge's stand, and compensate the timing of your dance. For a competition with a large audience, the measurements would be somewhat different when the audience is in the stands.

I bet no one does this. It's hard enough to be in sync with your partner!

So this is only a thought experiment, not a practical suggestion...

--------------------

I don't know much about acoustics, but here are some things that may or may not be completely correct:

In a modern concert hall, echoes, and the muddy sound they produce, as well as the sound suppression at specific locations (by destructive wave interference) they produce, may be suppressed by a combination of architectural shape, sound absorbing materials in or on the floor, walls and ceiling, draperies and curtains, and absorption of sound by bodies and clothing.

It is expected that a well designed P.A. system will attempt to minimize differences in time-of-arrival of sounds from the original source, the various speakers, and unsuppressed echoes, throughout the area of the audience. The P.A. system may also attempt to suppress residual echoes. An ideal (but impossible) hall in which sound arrives simultaneously at all points is "acoustically dead".

It is more complicated for a physically large music performance group, like an orchestra or large band, because they are large enough for sound to make syncing the group difficult.

It isn't always considered desirable to suppress all echoes in a concert hall: some "reverberation" is musically desirable. That is, a concert hall should be somewhat "acoustically live". The amount desired depends on the tempo and style of the music - e.g., clear voice requires greater clarity, and less reverberation.

Acoustics depends on the audience size and state of dress. So a good sound person must be employed to adjust the P.A. system at each event, and check for proper sound in various parts of the audience. That's why you hear "sound checks" before a concert.

Movie theaters do this too, but it is possible (this may be completely wrong!) they also try to sync the on-screen timing with the time-of-arrival of the sound. This goal is inconsistent with the goal of eliminating muddy sound throughout all parts of the audience, so a compromise may be reached.

For these and other reasons, the P.A. system of a good concert hall or movie theater is much more complex than a typical home hi-fi system, and requires substantial expertise to operate well.

I think that most ice rink buildings, and the P.A. systems they employ, largely ignore these considerations. Some rinks do better than others, but none I've been in do a good job at music and voice clarity, let alone simultaneity.

[taka]

The music system I'll skate to both in practice and testing is a sound system, amp and speakers on a trolley next to where the judge will be during tests (at the halfway line). It sounds pretty bad whether using those speakers or linked to the rink speakers. I kinda doubt anyone would be able to perceive a difference in time that small while skating round the rink at speed - there is usually too much else to think of!

[jjane45]

Rather negligible difference in timing, yeah. I'd rather they make sure music can start in time instead of holding the starting position forever...

[Query]

The maximum tempo of a compulsory dance is 198 bpm.

For that tempo, .2 seconds (=1/5 second) is a beat and a half. My coach gets mad at me for smaller errors.

OK, .2 seconds is a worse case scenario. (Unless echoes predominate, in which case it could be worse.) Nonetheless...

BTW, I did not mean to confine the discussion to ice dance. There may be cases when the sync between music and skating is important in freestyle and pairs too.

Anyway, it was just a thought experiment, as I said. Trying to sync to different parts of the beat in different parts of the rink would drive most skaters crazy. And designing a P.A. system to compensate timing at all frequencies in the presence of surfaces like the ice would be non-trivial.

 

[icedancer]

I can't read this discussion without going cross-eyed but I can tell you that the judges take into consideration the accoustics of the rink in arriving at decisions about test with respect to timing.   In ice dancing.

[aussieskater]

I also do flamenco, and can say that the difference does indeed matter in that discipline, as we often make 250+ "beats" per minute with our feet.  Our classes are held in a large hall, and the music is on a table (on a concrete step!) at one end.  Earlier this year, I was standing out of an exercise, near the table, and there was a 2+ beat delay between the music I was hearing and what the rest of the class was doing.  It was quite disconcerting.  I'd imagine the same issue would occur in many other dance forms (eg tap, Irish).

It's less of an issue for ice dance at our rink, as the rink's (crappy) speakers are mounted on the ceiling above centre ice.  From a sound delivery point of view, the placement is actually as close to perfect as they could reasonably get:  the rink is in a mall, and its ceiling is 3 storeys high, so the percentage difference of the various distances between the speakers and any point on the ice and the judges is pretty small.

[Query]

I can't read this discussion without going cross-eyed but I can tell you that the judges take into consideration the accoustics of the rink in arriving at decisions about test with respect to timing.   In ice dancing.

It is good to know that judges take this into account.

The music system I'll skate to both in practice and testing is a sound system, amp and speakers on a trolley next to where the judge will be during tests (at the halfway line). It sounds pretty bad whether using those speakers or linked to the rink speakers.

Not quite the worst possible scenario, but pretty bad. If it is an Olympic size rink, that is still 1/2 second delay to the far corners of the rink! Plus, the sound probably bounces off the walls, creating a very muddy sound. Must drive both the skaters and the judges crazy.

You could create rink acoustics "right" without fancy electronics. Use sound absorbing material in the walls, ceiling, non-ice flooring and bleachers, to cut bounces. Have an array of many highly directional speakers mounted high above the skaters, all facing straight down. Mounted same distance above all parts of the ice and the judge's stand. Put the same signal into all speakers, so the music is essentially simultaneous everywhere.

If you want the audience to hear it simultaneous too, you could mount similar speakers over them at the same height distance. However, most ice rinks are lower at the edges, so it might be easier to use a different height there, and use delay lines or other time-shift electronics to make up the difference.

There are a lot of things in the design of an ice skating facility or other public facility that architects don't usually do that they could. I'll put some suggestions in another thread.

[Skittl1321]

There are a lot of things in the design of an ice skating facility or other public facility that architects don't usually do that they could. I'll put some suggestions in another thread.

You might want to outline the cost (including time) of these things they 'could' do.  I bet I can guess why they don't!!!

[Query]

Here is the thread I'm putting this somewhat separate topic in.