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Acoustics textile and an anechoic chamber

October 31, 2005

Today I was in charge of the ongoing workshop on acoustics and textiles. I’d prepared for three sessions on different topics but then along came a fourth and really exciting one.

PART I – SELF PRESENTATION

In the morning I gave a self presentation showing documentation from various sound installations I’ve been doing and talking about them. I’ve been doing quite a lot of self presentations over the last two years. At one point I was getting really tired of myself but I now find that it’s quite interesting and worthwhile for myself to do this kind of presentations. My own focus what problems I’m currently concerned with etc. changes with every project I’m doing and doing this kind of presentations becomes a vehicle for seeing earlier projects in a new light. Given the topic of the workshop and my recent experience with the White-out installation at USF I tended to select installations based on if/how they dealt with the acoustics of the space:

  • Texture I – First installation I did apart that it was never properly presented. A turning pojnt for myself towards working on sound instead of written music as well as moving from concert setting to installation/sound in space.
  • Ekkofisk: Last week Tor Halmrast had been talking about formants. We used formants as part of the voice synthesis. I also played them some examples of how the synthesised voices sounded without any reverb to illustrate how important the added reverb was to creating an illution of authentic voice.
  • Motlyd – I mainly talked about how Maia Urstad and Jana Winderen managed to visually transform the room so that the sound was “on display”.
  • Norway Remixed – Mainly focused on the experience when working on sound in public space problems raised our attempted solutions and experience gained as part of the project. This project also gave an example of using parabolic loudspeakers as well as a custom-designed room intended to prevent sound leaking back and forth between the installation and the outside space as well as controlling the acoustic properties of the room used for the main part of the installation.
  • Dialog/Overgang (Dialogue/Transition) – how I wanted to use the space as well as the acoustic properties of the space. For some reason this is the best gallery space I’ve ever worked in acoustically quite surprising considering the dimensions of the room (approx. 60 × 10 × 4 meters). The two possible explanations I can think of are that all of the floor had carpet functioning as an absorber. In addition I believe that the surface areal of floor walls and ceiling is relatively high compared to the total volume of the space. Thus according to the Sabine Absorption Equation the decay time should be shorter than immediately expected for such a large space.
  • Elektropoesia – For this installation a custom room was built at Malmökonsthall. The room had double walls for sound insulation but the surfaces of the room were all hard (wooden floor gypsum board) so it was quite reverbant. I also suspect that it had quite a few resonant frequencies.
  • White-out – Visningsrommet USF is by far the most challenging room I’ve ever worked in acoustically. It is subdivided into two rooms. The outer room is wide open to the rest of the world including the automatic door just outside as well as the café across the corridor. This implies a lot of intruding noise. The inner room is all very hard and non-absorbing surfaces: concrete floor and walls gypsum boards concrete roof. It was more or less impossible to develop sound for the installation out of the room. Anything developed at home or the studio turned out not working in the space and I had to develop all of the sound in the room. I managed to get it working in the ned but I want to avoid a similar situation in the future if I can.

PART II – PRACTICAL DEMONSTRATION

I’d prepared a Max patch that was easy to fiddle around with in order to do a practical demonstration of some of the concepts introduced last week by Tor: Frequency wavelength spectrum harmonic content formants logarithmic perception etc. I also played a sound file with some text and applied reverb (Audio Ease impulse responses) to it while looking at the sonogram. It was quite instructive to see how all transitional sound was smeared out if the reverb got big enough.

PART IIIODDS AND SODS

This section we didn’t get time to do. I’d planned to present some music and sound art that I find interesting and that is dealing with space in one way or another. Also wanted to present some sound art that seems to be tangential to the projects the students are currently working on:

  • Giovanni Gabrielli – Sacrae symphoniae for the Basilica San Marco di Venezia
  • Vivaldi – Concerto RV 522 for Violine – Principale – and Violine – per eco in lontano -
  • Bill Fontana – Acoustical Visions of Venice and Landscape Sculpture With Fog Horns
  • The World Soundscape Project
  • John Cage – 4’33" and his eperience with the anechoic chamber
  • Alvin Lucier – I’m sitting in a room
  • The Philips Pavilion 1958

PART IV – EXCURSION

ANECHOIC_2.JPG

While I was lecturing I received a call from Haukeland confirming that we could come to see the anechoic chamber. Of we went in a maxi-taxi. I’ve posted more photos at Flickr.

Afterwards we continued to “Bygg for basale bilogifag” a university building nearby. Natasha Barret has a permanent sound installation at the building. Her installation has caused some controversy among the users and unfortunately it was shut down today. I don’t know if this was an occational occurence or is now a more or less the permanent state but the staff at the reception desk didn’t exactly appear to be eager to help us getting in touch with whoever is maintaining the installation in order to turn it on…