The Frontal Cortex

The Sound of Silence

Speaking of the senses, it’s always fascinating what happens when that sensory spigot is turned off, so that the cortex is suddenly filled with silence. Jad Abumrad, the co-host of Radio Lab (download their new season!), recently spent some time in an anechoic chamber, or a room designed to stifle soundwaves and erase echoes. The brain, it turns out, can’t stand the quiet. When confronted with utter silence, it starts to hallucinate:

Deep in the bowels of a nondescript 1950’s era government building is Bell Lab’s very own anechoic chamber, no longer in use. The nice folks at Bell Labs agreed to open it up for me. It’s a frightening room at first glance. The door is a thousand pounds, the walls ten feet thick, and everything – floors, ceilings, all surfaces – is covered in yellow acoustic baffling. Stranger still, the floor is made of a wire mesh grid and suspended ten feet off the ground (to prevent sound reflecting off the floor).

I remember thinking two things as I walked in. One: this place looks like a beehive. Two: I can’t believe how much work it takes to keep out sound. Door closes. Lights off.
Consider: Every room, even the very quietest rooms, have a tone (in fact, in the radio business, we call this “room tone”).

But this room had NO ROOM TONE. No sound at all.

And it’s impossible to describe what true silence does to your ears. The moment the door went thwuck shut, my ear drums started to flutter. As if air was trying to force it’s way out my ears in little puffs. Felt a wee bit nauseous. Crackling. Like shadow static. I think my ears were physically searching for sound.

After about five minutes… A brief, very vivid flash of bees buzzing, like a swarm zooming by my head, doppler style, en route to attack another hive. I’m no idiot. I know my mind invented the bees because ‘bee-hive’ was one of the last thoughts in my head before the lights went out. Regardless, the sound of bees in the dark was disconcerting.

After about twenty minutes, I began to hear a high pitched whine, which persisted. Not a hallucination, I’d later discover. According to the Bell Labbies, this was probably the sound of my circulatory system. I also heard the gentle thud of my heartbeat.


  1. #1 6EQUJ5
    April 21, 2008

    In high school I got a tour of the anechoic chamber at Radioear, maker of hearing aids. I couldn’t hear the silence until I held my breath, which momentarily silenced the racket my shirt was making crinkling while I breathed in and out.

    If you slowly turn your head, you can hear your neck muscles moving.

    Yeah, it was awesome.

  2. #2 ROC
    April 21, 2008

    The sound you speak of is know in the world of meditation as the sound of silence. It is the point where awareness originates, know by yogi’s and monks as the unconditioned. This sound exists at all time, under all conditions, a well trained mind can find the sound at any point intime, under any condition. It is thst sound that exists between out thoughts, in seek its origin one is lead on the path of enlightenment…..

  3. #3 Andrea Grant
    April 22, 2008

    I’ve read that tinnitus might be related to this refusal of the brain to have silence–that somehow that’s gone a bit awry and some of us hear those silence-hallucinations in the absence of silence. Tinnitus sufferers are advised to never be in total silence if at all possible. Aside from that being good practical advice, it also made sense to me in light of the fact (as one site pointed out) that in nature we are really never in total silence, so why would the brain be adapted to coping with that? It also makes me not mind the miniature freeway outside my apartment so much–white noise is white noise, right?

  4. #4 Tom Raworth
    April 23, 2008

    The composer John Cage (from Wikipedia… I no longer have the original Cage book.)
    “In 1948, Cage joined the faculty of Black Mountain College, where he regularly worked on collaborations with Merce Cunningham. Around this time, he visited the anechoic chamber at Harvard University. (An anechoic chamber is a room designed in such a way that the walls, ceiling and floor will absorb all sounds made in the room, rather than bouncing them back as echoes. They are also generally soundproofed.) Cage entered the chamber expecting to hear silence, but as he wrote later, he “heard two sounds, one high and one low. When I described them to the engineer in charge, he informed me that the high one was my nervous system in operation, the low one my blood in circulation.””

    He later said “In the late forties I found out by experiment (I went into the anechoic chamber at Harvard University) that silence is not acoustic. It is a change of mind, a turning around. I devoted my music to it.”

  5. #5 Anonymous
    June 17, 2008

    The little bit of tinnitis everyone has can be described as the neuro equivalent of electronic noise, like the hum of an amplifier. A room like described would probably be too goof for a bedroom.

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