Death of a Dead Room

The late anechoic room of HKU University of the Arts Utrecht

Last Monday I dismantled part of the anechoic chamber in Hilversum that has served me so well for more than 16 years. HKU University of the Arts where I teach moved to Utrecht and unfortunately we could not take the chamber with us so it will be wasted. There are few other spaces where I learned so much about sound, acoustics and psycho-acoustics.

Contrary to popular believe, listening to recordings on a stereo sound system in an anechoic room is extremely interesting. For instance, I let many generations of students enjoy the incredible surround imaging of the Q-Sound effects in the “Ray of Light” album by Madonna. No contemporary immersive sound system will ever beat that. But we also listened to puristic classical music recordings, made with just two omnidirectional microphones, that offered a unique listening experience in this room.

Which brings me to the late Onno Scholtze, my friend and Philips Classics recording engineer, with whom I spent many hours of listening in this anechoic room after he retired. He brought Björk and Madonna, old recordings from his Philips days, and new wonderful recordings made with just two DPA 4060’s in the Concertgebouw and the Berliner Philharmony. But also the fantastic hour long soundscape of a sun rise in the Dutch polder (imagine the birds waking up).

Together with Onno I once worked on a book plus CD’s called “Checkpoint Audio” and in memory of Onno and the Hilversum anechoic room I will offer a track of that as a present. This track was a recording Onno made in the famous Vienna Musikverein with two miniature DPA 4060 microphones in a standard 40cm AB setup. Onno walks around on stage while talking and clapping his hands. The noise level in this recording is noticeable due to the soft voice sound level relative to the airconditioning noise and the self noise of the microphones. But the unusually precise rendering by these small microphones of the width and depth image is exemplary. If your stereo system is of good quality you will be able to follow Onno from step to step on his journey over the stage.

The late anechoic room of HKU University of the Arts Utrecht
The late anechoic room of HKU University of the Arts Utrecht

How is it possible to hear depth perspective in a recording? In real life, your brain localizes a source by the interference of the direct sound with the early reflections. If a source is 0.5m far and 1.5m above the ground, the floor reflection arrives 7.4 milliseconds after the direct sound. If a source is 10m far and 1.5m above the ground, the floor reflection arrives only 1.3 milliseconds after the direct sound. Something similar happens to the other reflections. A good recording captures these cues. If you like to hear the cues at home, your system should not mask them by adding too loud reflections from nearby side walls etc. As you can imagine, in the anechoic room the perception of depth in stereo recordings was phenomenal.

If you are curious about how well your own system renders the width and depth perspective cues of a recording, please collect your present by downloading the track below that Onno Scholtze recorded in the Vienna Musikverein.

Eelco Grimm