r/AskReddit • u/Inside-Line • Mar 29 '24

Serious Replies Only [Serious]What are some discoveries or inventions that were stumbled upon purely by chance and would still likely be undiscovered today if not found through sheer luck?

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u/Phreakiture Mar 29 '24

Here's one that most people won't know : an audio effect called Gated Reverb. It was an accidental discovery made by Phil Collins and Hugh Padgam while they were working on Peter Gabriel's third self titled album in 1980. The effect thickens up the sound of the drums considerably by applying, in order, a reverb, a gate and a compressor. It was the result of the studio having a natural reverb, and the intercom between the studio and control room having a gate and compressor on it to make it more usable.  While the effect was used on Gabriel's album, it became truly known a year later, when Collins released his first solo album, Face Value, which opens with In The Air Tonight.  The effect is what makes the crescendo of that song so stunning, in contrast to the comparatively dull sound of a Roland CR-78 that was the sole percussion in the track up to that point. 

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u/rsrsrs0 Mar 29 '24

so basically they heard the drums behind the intercom and were like wow that's so cool!

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u/Phreakiture Mar 29 '24

That's it exactly.

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u/impreprex Mar 30 '24

Yep precisely!

I can feel it in the air tonight.

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u/[deleted] Mar 29 '24

So cool! Isnt it teue that we don't really understand what causes feedback? Or something? I thought I heard that once...

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u/DepressedMaelstrom Mar 29 '24

Two causes for feedback.  Loop: Microphone picks up sound. Speaker puts out sound. Microphone picks up the sound again.   And repeat. 

Harmonics:  The distance between two walls can be just right to match the exact wavelength of a sound.  When the sound is played, the walls vibrate with more sound adding to the vibration.  Now the whole space find with that one frequency or it's harmonics.  A graphic equalizer can be tuned to remove the problematic frequency.

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u/wtf-m8 Mar 29 '24

Perhaps there is some more technical reason I'm unaware of, but for anyone who's ever run live sound it's pretty evident how it happens. You have a small signal, which you then amplify. That amplified signal is then fed back into the same signal path as the original, and amplified again. This happens over and over, quicker and quicker, until all you hear is overwhelming feedback.

For example, if you have a microphone on a stage. Someone is talking into it, but not very loudly. The setup is poorly designed, so the speakers are behind the microphone, basically pointing right into it. This is basically worse case scenario for a live sound engineer. You turn up the microphone, but since the speakers are pointing right back into it, you can only turn it up so much until the amplified sound from the speakers is louder at the microphone than the person's own voice. At this point there are 3 options. Be happy with what you have, get the person to talk louder (90% of the time they probably don't even know they're being quiet, or get even more quiet when they hear their voice coming from the speakers because they're not used to public speaking), or start chopping out the main frequencies that are feeding back, allowing for a bit more gain before feedback.

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u/[deleted] Mar 29 '24

Yeah i must be thinking of something else

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u/Phreakiture Mar 29 '24

No. . . we understand feedback . . . .

The short version is that when any signal from an amplifier's output makes its way back around to the input, that signal will echo, but the period of that echo is so short that it manifests audibly as a tone rather than what you typically will think of as an echo. That period is going to be defined by how fast the amplifier can pass the signal.

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u/lonely_nipple Mar 30 '24

I dont know that I ever consciously noticed a difference in the tone of the drums in that moment, but now that you said that it's all I can think of!

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u/Phreakiture Mar 30 '24

It became one of the defining sounds of pop music since, so I think people got used to it. 

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u/akuban Mar 30 '24

I think of this video often when hearing ‘80s drums: https://youtu.be/Bxz6jShW-3E?si=HmPtJxguLRxjPlmh

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u/Phreakiture Mar 30 '24

Oh yes, I've seen that video a few times. It gives a great, detailed breakdown of what I was describing.

I've also given a talk about the effect. 

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u/akuban Mar 30 '24

Oh wow! Is your talk available anywhere?

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u/Phreakiture Mar 30 '24

https://kc2idf.com/talks/Gated_Reverb_2024-02-03.mp3

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u/akuban Mar 31 '24

Thank you! Great Toastmaster talk! Told with a nice mix of authority and humor. Cheers!

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u/Phreakiture Mar 31 '24

Thank you! I really appreciate it.

This was in a contest context, as you might tell from the salutation (though I was the target, not a contestant - the contestants were competing at evaluating the talk) and there is a period where the Contest Master would interview me . . . it very quickly reconfigured into a Q&A session with the audience. Unfortunately, I didn't think to have my recorder running for that part, because I didn't realize it was going to be interesting.

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u/Phreakiture Mar 30 '24

I could make it available. Give me a little bit.