The Acoustical Design of UCSD's Conrad Prebys Concert Hall
A new music venue opens this weekend on the campus of UC San Diego. The Conrad Prebys Music Center includes a state-of-the-art, 400-seat concert hall designed for chamber ensembles. The design is ideal for experimental music, which is a strong focus of UCSD's music department. Arts producer Angela Carone found out what it takes to design a building that showcases music.
I'm sitting in the first row of the new Prebys Concert Hall at UCSD where a chamber orchestra is rehearsing composer Rand Steiger's latest work. The piece is dedicated to Cyril Harris, the renowned acoustical engineer, now in his 90s who designed the acoustics for this concert hall.
Steve Schick is standing on the stage of the hall. He's a percussionist. He's going to use a gong to demonstrate the journey of a musical note.
Schick begins, "We have the note, it's strike (sound of gong), and as soon as its struck, it starts to travel. And the first thing that happens on a wooden floor like the one I'm standing on, is it bounces off of the floor. Then it bounces against the back wall of the auditorium, and the right angle of those two things presses the sound forward towards the listeners."
Schick traces the note's path with his hands, pointing to the walls and ceilings where triangular panels extend in different directions. He continues, "and so the sound is literally bouncing around like a pinball machine. Bits of the gong are bouncing off the ceiling and off the walls to the point where you can be sitting in the middle of the hall and you have the sensation that the gong could be coming from behind you, or from above, or even from within you because of the way the sound is being diffused and reverberated by the structure."
Diffused and Reverberated? Let's explain these terms, since they are central to proper acoustics in a concert hall.
Architect Mark Reddington says "reverberation is the amount of time it takes a sound to decay from the point it's first made to the point at which you can no longer hear it. "
Reddington and Harris designed the concert hall together. When a room doesn't have good reverberation, the music can sound flat. Musicians refer to it as a dry room.
So how do you create a building for proper reverberation? You start with the right materials. The Prebys Concert hall is made of layers of heavy plaster, topped by bamboo veneer. The material must be dense so sound reflects off of the surfaces. This creates diffusion.
Reddington explains, "Diffusion is the capacity of the room to scatter all of the different wavelengths or sounds created by the instruments."
The notes scatter from the stage, bounce around the room and eventually land in the listener's ear. A room can be designed to create optimal bouncing, which brings us back to all of those triangles jetting out from the walls and ceilings of the Prebys concert hall.
Reddington says, "The triangular geometry by its very nature is an ideal shape for scattering the wide range of sound frequencies that are generated in the music."
The points on a triangle reflect sound in one direction while the sides reflect it in another. All of this bouncing of sound creates density, which makes the music sound rich and full.
The acoustics in UCSD's new concert hall mark the culmination of Cyril Harris' distinguished career designing concert halls all over the world. Harris is now retiring, but Reddington says he's leaving the field on a personal high note. "I think Cyril is very proud of this. I think he sees it as a realization of the ideas he's been exploring in architecture and acoustics for his entire career. "
For KPBS Radio, I'm Angela Carone.
There will be a public concert at the Conrad Prebys Concert Hall on Saturday, May 9, at 8 p.m. There will also be a free Open House on Saturday from noon to 4 p.m.