Why do engine exhaust sounds get louder and higher pitched as RPM’s increase?



Also, does exhaust pitch stay the same, given the same RPM but in different gears? I ask because it sounds like pitch decreases as you go into higher gears.

In: Other

In a given gear, the pitch will increase as the RPM increases. After the shift to the next gear, though, rpm _decreases_after the shift because the ratio changes downward(to a lesser gear ratio)

Your second question would depend on the design of a given gearbox — there should be overlapping regions where the geartrain speed would be the same, but the exhaust note is determined by several factors — acceleration, RPM, muffler type, the grade the vehicle was traveling — so it’d be hard to say.

Louder and higher pitched are two different things. One is frequency the other is amplitude. So for example the human ear can hear frequencies from 20-20k Hz. Where frequency just means how often something is happening in a given time and Hz denotes that his time is a second. So idk 26400 rpm (revolutions per minute) would be 440 Hz or an “a” in musical pitch. If it goes faster it gets higher if it runs slower it goes lower.

So if you’d picture your ear drum, the pitch is how often it gets pushed around in a second, while the amplitude (the loudness) is how far it’s pushed. So a loud signal can be slow moving an low pitched while a high pitched signal can be very quite.

“Higher pitch” means higher frequency: The air moves back and forth with a higher frequency. Higher rpm means engine parts move back and forth with a higher frequency, and correspondingly the air does the same. If you shift to a higher gear the rpm goes down (at the same car speed), so the pitch goes down again.

As a general guideline, more engine power makes the engine louder. And higher rpm means more engine power.

To the different gear question, a lot of it has to do with engine load. An engine free spinning requires a lesser air fuel ratio in the combustion chamber than an engine starting out in first gear. Likewise, the engine load changes when the gear ratio does