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« run, baby, run | Main | a walk in the park: part II »


One of the great things about blogs is instant feedback... thanks, Jennifer for the mention! For the sake of completeness I thought I'd add/modify a few things above (it was, after all, 98deg outside and we weren't taking notes... the paper would have simply melted).

Anyway, first off, about the no-right-angle-corners on stage it's actually not so much that it would send too much energy back to the musicians on stage. With a right angle the sound just comes right back to the person who generated it (sound follows law of incidence/reflection for the most part). We have the obtuse/acute angles to make sure that everyone else in the orchestra can hear you as well as you can hear yourself. We have sound-absorptive curtains that get pulled out to cover the walls--and many paths for sound reflections--for heavily amplified concerts.

For the walls with the wood perforations... we weren't trying to absorb sound so much as we were trying to scatter it, and only the high frequency stuff. Yes, the holes are varied in diameter and spacing to maximize the range of the high frequencies that were being scattered. There are a few spots, right behind the timpani position upstage, for example, where there's nothing behind the perforated wood... gives the excess soudn energy somewhere to "bleed" to.

Regarding the reverberation time settings we have "dialed in" to the LARES system... it's not so much that we need to pump more energy into the large volume. Rather, it seems to be a purely perceptual effect. If you walk a person into a concert hall space and let them listen to a 2-second room, then walk them out to the Pritzker Pavilion and through 4-seconds of reverberation at them, they'll probably tell you that they have similar levels of reverberance. We have several ideas for why this is (maybe the background noise is so high outside that you only hear 2-seconds of reverberation before its inaudible? maybe the very large "perceived" volume makes your brain want to hear more reverberation?) but nothing confirmed.

One final note on the delay times set on the delay ring loudspeakers. You quoted me correctly but I explained incorrectly... once there are electronics are in the picture we have other specialists in my office who design this and I quoted them wrong. Here's the real deal: yes, we do have the delay times on the delay ring loudspeakers a touch off of being perfectly time-aligned. And while the possible interference effects are there, the main reason for the offset is the "precedence effect", whereby your brain processess a collection of sound wave as if they were all part of the first wavefront that arrives at your ear. We set the delays such that the the wavefront from the main stagefront loudspeeakers arrives first, followed a few milliseconds later by the delayed sound. This helps keep your perceived "image" as coming from the stage rather than from over your head somewhere. The fun part is, even though there is plenty of science to back up the initial settings, the real fine tuning is done by ear on a subjective basis. That's why you want to make sure your audio designers don't go deaf.

Quick note on Chicago Shakespeare: yes, it's real brick on the inside of the theatre.

Hopefully this reads like the "for further information" addendum it's intended to be rather than any kind of wonky correction. It was great meeting you in person, Jennifer, and hope the rest of the time in Chicago with Future Spouse was fun.

One other note I missed (and I hate to be a repeat commenter like this): the only thing that the risers at Disney and the Pritzker Pavilion have in common is the physical layout... the size of each riser piece is the same (Gehry's office simply copied and pasted it on the drawings and it was an acceptable layout for us). The wood at Disney is a very soft cedar, the wood at Pritzker is a more durable maple, etc.

The MAJOR difference is the resilient support of the risers. The "floating" riser tops, which help transfer vibrational energy from one part of the orchestra to another (so you "feel" the music as well as hear it to keep in good ensemble with one another) has not been done anywhere else before. I personally had no part in their design, but the other folks at my office might get very fussy if the Disney acousticians got credited for it!

What a timely post! I'm going to be visiting Chicago for the first time ever next month, to attend a meeting of the Astronomical Society of the Pacific. I was wondering what was in Millennium Park, and now I know. I'm really looking forward to part 2.

As a longtime Chicago resident, I mostly approve of the Pritzker Pavilion ... except that from any angle except south-and-somewhat-east, it looks like half-built SCAFFOLDING. If nobody ever looked at it except FROM Millenium Park, that'd be fine, but the backside of the pavilion is right up against some seriously busy parts of Chicago, and it's just careless and ugly from that angle.

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    Physics Cocktails

    • Heavy G
      The perfect pick-me-up when gravity gets you down.
      2 oz Tequila
      2 oz Triple sec
      2 oz Rose's sweetened lime juice
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      Mix tequila, triple sec and lime juice in a shaker and pour into a margarita glass. (Salted rim and ice are optional.) Top off with 7-Up/Sprite and let the weight of the world lift off your shoulders.
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      The perfect nightcap after a long day struggling with QED equations.
      1 oz dark rum
      1/2 oz light rum
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      1/8 tsp ground nutmeg
      In a shaker half-filled with ice, combine the dark and light rum, Tia Maria, and cream. Shake well. Strain into an old fashioned glass almost filled with crushed ice. Dust with the nutmeg, and serve. Bongos optional.
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      Electrify your friends with amazing pyrotechnics!
      2 oz brandy
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      1 oz fresh lemon juice
      Combine Campari and lemon juice in shaker filled with cracked ice. Shake and strain into chilled cocktail glass. Heat brandy in chafing dish, then ignite and pour into glass. Cocktail Go BOOM! Plus, Fire = Pretty!
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