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A Sound Education

Hidden Messages

Pasted Graphic
Buzz Aldrin subliminally making the flag fly straight.
"Fly straight, you beep flag."

Hidden Messages


When astronauts first walked on the moon, everyone was glued to the television. I was eight-years-old and can remember it like yesterday.

Beep. Beep.

We copy you down, Eagle.

Beep. Beep.

Engine arm is off. (Pause) Houston, Tranquility Base here. The Eagle has landed.

Beep. Beep.

What the beep? All those old NASA transmissions seem to have that beeping in the recording. What the beep is it? It's actually two, and they're called Quindar tones.

They were named after the manufacturer, but I think it sounds very '60's Sci-Fi:

"I am from the planet Quindar in the Crouton system. We think your planet is just groovy, baby!"

In a nutshell, the tones signaled remote transmitters to turn on or off. Installing two separate lines of communications, one voice and one data, between Cap Com (Capsule Communications on earth) and the transmitters around the globe would have been extremely costly. So they went with a single channel, and that's why we hear them in the recordings.

This wasn't a new idea. All of us who had to endure a film strip in school remember the tones that told the teacher to advance the film strip. Radio networks used it to signal its affiliates, like the "N - B - C" chimes.

Later, radio networks adopted a different method to cue automatic playback systems at their affiliates with "sub-audible" tones. In reality, they were just low tones like 25. 35, 50 or 75 Hz that were filtered out of the on-air stream and redirected to playback equipment.

An announcer's voice can also be a cue for radio stations. In sports broadcasting for instance, how an announcer goes to a commercial break can cue the broadcast engineer at the local radio station whether or not to play local commercials. If a block of commercials will be all network spots, the announcer might say:

"We'll be back after this on SRN."

If the upcoming break should include local commercials, the announcer might say:

"We'll be back after this. You're listening to the Sports Radio Network."

But the ultimate in hidden sounds has to be subliminal messages in advertising, public address systems, and music. Remember "Paul is dead" from The White Album? How about rumors of hidden messages in department store music, factory brown noise, or even advertising? It's easy enough to do, but is it effective? Studies have found that visual stimuli are more effective than audible stimuli. But it doesn't stop people from trying. I think I'll try. Say the following aloud:

Isn't it a nice day. use You should really go to the country. dynamix Take a picnic basket along. for Enjoy the breeze. all Marvel at all the green. your Smell the blooming flowers. audio Enjoy yourself!

Did You Know?


"That's one small step for man, one giant leap for mankind"


Neil Armstrong meant to say "That's one small step for a man," but flubbed his line in the excitement. The one word, or lack thereof, changes the whole meaning. NASA said that static obscured the one little word, but ground recordings are clear and audible. Armstrong hesitated after he said "man," probably realizing his mistake. Having been awake for 24-hours and being the first person on the moon, I would have probably messed up as well...and fell off the ladder landing face up and helpless like a beetle.

Tech Notes


When NASA Cap Com would initiate the conversation with a spacecraft, they would press and hold a button that would produce two tones. This simulated the push-to-talk (PTT) action on a walkie-talkie. The first tone was the "intro" or a "ready" tone for the automatic systems that controlled the transmitters. The next tone, slightly different, told the transmitters to un-mute the audio.

CapCom would then initiate conversation. When everything needed to be said, they would release the button. Once again, a ready tone would sound followed by a slightly different tone. This told the transmitters to mute the audio.

The spacecraft usually didn't hear the tones because a filter was applied that tuned most of the tones out. Unlike a walkie-talkie that mutes incoming audio while transmitting, Cap Com could always hear the spacecraft if they transmitted while Cap Com was also transmitting.

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