Ask yourself where the quietest place in Hong Kong might be. The deserted school corridors during a T8? A remote island? When you think about it, there aren’t many silent places in this chaotic city. That’s why researchers studying sound need specially-designed equipment to help them block out all other noises while they work.
Last month, five junior reporters visited the department of mechanical engineering at the University of Hong Kong (HKU). The department's engineering manager, Scott Chan, led them to the school’s anechoic chamber, a lab built to minimise sound and mimic the acoustic effects of outer space.
Built in the ’80s, this fascinating, alien-looking chamber was the first of its kind in Hong Kong. The walls, ceiling and floor are covered in large, metal, triangular prisms, which absorb sound waves instead of letting them bounce back, while the door is double-sealed to prevent noise leaking in. These ultra-soundproof conditions are ideal for Rocky Fan and Kevin Woo, two PhD students who need to isolate noise for their acoustic experiments.
Earlier this year, a journalist claimed that spending more than 40 minutes in the absolute silence of an anechoic chamber would make you lose your mind due to being able to hear all your internal organs gurgling around. We weren’t able to test this theory due to the sound of breathing, rustling clothes, and a constant stream of questions directed at Fan and Woo. However, even a two-minute-long period of silence was eerie and even physically uncomfortable: the lack of echo made it feel like someone could be stood behind you without you knowing it.
We stepped out of the chamber feeling dizzy, and sounds we would not usually notice – like the air con – suddenly seemed loud and intrusive. It became clear how noise is just another unavoidable source of pollution in the city.
The junior reporters explain how they felt during and after being in the chamber:
Being inside the chamber completely redefines your perception of silence – even the floor absorbs sound. I felt slightly lightheaded and extremely uncomfortable when we stood silent for a few minutes, because it was just so different.
An ear-ie experience
The anechoic chamber was quite surreal. In this rare pocket of quiet amid the cacophony of one of the busiest cities in the world, we could hear our own heartbeats. There was an uncomfortable amount of pressure on my ears; I almost felt like I was on a plane.
Super soundproof, at least
Though the chamber might not be home to a giant basilisk, it does a very good job of confining sound to just one room.
The room is small, and when all the doors are closed, it is stuffy, hot, and a little claustrophobic.
If you stay in there long enough, any tinnitus, or a ringing in your ears, becomes obvious. The room is so quiet that you can hear a creepy mid-frequency ringing – the sound of electricity running through the computers in the room. Could you go crazy in these rooms? Probably.
A little bit frightening
I went to HKU with close to no clue what an anechoic chamber was. It certainly has a useful and interesting purpose, but once you’re inside, it’s actually quite scary, and even more so if you have claustrophobia.
I enjoyed the uniqueness of the chamber a lot. My ears didn’t feel uncomfortable at all, but that doesn’t mean it felt normal, either. It was really interesting to learn about the triangular spikes on the walls, floor and ceiling, which absorbed all the sound waves. Any air conditioners in the room would have affected the experiments by causing noise interference, so it was very hot inside. It was definitely the experience of a lifetime – if you get the chance to try it for yourself, don’t miss it!