Anyone who’s ever witnessed a poker run knows that Harley-Davidson motorcycles are really, really loud. And since not everyone thinks that’s a good thing, in recent years, there have been efforts to stifle them.
Straight off the line today, Harley exhaust systems can emit noise as high as 80 decibels (dBs), give or take depending on the model. For reference, a typical car when idling emits noise at about 35-45 dB and in the high 50s to low 60s decibel levels at freeway speeds. Even something like a 2008 Ford F-450 truck only gets as loud as 51 dB when idling and 68 dB when traveling at 65 mph.
And while you might think 68 dB isn’t that far off 80 dB, it’s important to understand that the decibel system is logarithmic- in this case, an increase in 10 dB means that this sound level is ten times more powerful. So, for instance, 80 dB would be ten times more sound pressure than 70 dB. For further reference, when you’re talking with someone in a normal speaking voice, you’re usually talking at about 60 dB and a lawnmower is usually around 90 dB while a typical military jet engine averages about 120 dB.