Acoustics on the Road: Phase Cancellation and Your Car Muffler

Two things most people don’t care to understand: physics and how the heck your car works. But you’re different. Why, you probably already know that phase cancellation occurs when a sound source is delayed slightly (by a real-world reflection, or in recording and mixing), so that two coherent waveforms of opposite phase are superimposes and cancel each other out. (Er, in plain english: one wave’s crests cancel out the other’s troughs and vice versa.) Now, did you know this principle is what keeps your car’s exhaust from making a racket? How Mufflers Work [Howstuffworks] Basically, the muffler is a chamber …

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Before Radar: Acoustic Locators

Before the invention of radar, you'd need a large dish or horn to track sounds of your enemy. "Acoustic radar" (aka "acoustic locators" or "sound mirrors") captured sound via large dishes or walls, or steerable horns not unlike the cones on early record players. Douglas Self has a reference guide to this curious technology with links as part of his Museum of Retro Technology. (via near near future) Check out the fluidic gramophones, too! I know what you're thinking: could you sample the sounds captured by such a dish? I leave it up to our UK readers to head over …

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