Active Noise Cancellation (ANC) is a technique that involves a speaker and a microphone. The waveform picked up by the microphone is inverted and sent to the speaker, and through destructive interference you end up with (hopefully) nothing left. It works particularly well with regular, consistent sounds like hums and machine noise.

Proposed is to fit an ANC system around the brakes of all motor vehicles in London. Thus, no matter how badly toed-in or rusted these brakes are, there would be no more banshee shrieks of death at every bloody red light.
-- mitxela, Oct 06 2016

Doesn't work except at localized points if I recall.
-- RayfordSteele, Oct 06 2016


Why not?

Tyrell: Because by the second day of incubation, any cells that have undergone reversion mutations give rise to revertant colonies like rats leaving a sinking ship. Then the ship sinks.

Roy: What about EMS recombination.

Tyrell: We've already tried it. Ethyl methane sulfonate as an alkylating agent - a potent mutagen. It created a virus so lethal the subject was dead before he left the table.

Roy: Then a repressive protein that blocks the operating cells.

Tyrell: Wouldn't obstruct replication, but it does give rise to an error in replication so that the newly formed DNA strand carries the mutation and you've got a virus again. But, uh, this - all of this is academic. You were made as well as we could make you.
-- normzone, Oct 06 2016


If only the brake that screeched twice as loud screeched half as long.
-- mitxela, Oct 06 2016


Thought these might be brake pads with Nelson Mandella's face print on them.
-- xenzag, Oct 06 2016



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