I have always been curious no one has really been able to tell me what type of muffler would sound deeper and louder a 2 inch pipe that is say 16 to 19 inches long or a 3 inch pipe that is 27 to 30 inches long ?

I'd think exhaust pipes would behave like other open-closed standing wave pipes. Length of the pipe would be 1/2 the wavelength of the fundamental and the diameter would be the amplitude.

In a perfect world with a smooth bore cylindrical pipe and all other things being equal, longer=deeper and wider=louder.

When I was bulding my exhaust I experimented with length, but not diameter. I can tell you that longer definately = deeper, but not sure how much the diameter does.

I actually took two shopvac extensions and sliped them onto the header, and it sounded like a helicopter was about 50 feet above my head , but only for about a minute though cause i didn't want to melt them.

JakeB

I would think (though I'm just guessing) that the reason larger instruments have a larger diameter is that lower notes don't "cut" as well. Something about the way the ear works makes us pick up on high notes much better than low notes. I think the reason that choir melodies are always written for the soprano part is that everything else sortof blends together; the soprano voice really stands out, despite not being any louder than anyone else, decibel-wise. So in order to sortof "equalize" the sound your hearing, I'm guessing they open up the diameter of the larger instruments, though its not always the case (trombone).

Then again, most of those large diameter instruments (sax, tuba, cornet) have a conical shape (so you can fit your mouth on one end), rather than a cylindrical shape (flute) so  i think that really messes things up too.

Acoustically, the vowell sounds fall somewhere between 700 and 1200 Hz (cps) while consonants fall above 1500 going up to around 7000 Hz (cps).  In most languages, the consonants carry the distinctive information Kats compared to Hats.  Also, the lower frequencies bend more (you can hear drums in a marching band before they come around the corner, the fifes are more line of sight.  Other aspects are the upwards spread of masking, due to the wave formed in the cochlea and the basel first part is high frequencies and the higher up the cochlea 9or deeper into it, the lower the pitch.  For some reason, the wave formed gets more before the highpoint, or specific frquency stimulated, then drops off fast not exciting hair cell beyond..OH, SW, I think Hawiian is one of the few languages that has more vowells than consonants.  I expect the diameter has much to do with tone (base =wider tube/ treble = narrow tube all of which I think may be due to harmonics and which waves (Hz/cps)flow best through a given tube.

Trippah, appreciate you post on frequency, I am very hard of hearing from diesel engines turbochargers in my misspent youth and even with digital aids, I have a spot at 2K hz that is flat. The hearing aid tech can crank up the volume but it doesn't help just distorts it in that area. No one explained it quite like you do, I'm going to copy it and share it with my Automotive teacher friends who are starting to notice problems in noisy classrooms and understanding students questions. We have talked about it and one class I sub in for them on occasion has the HVAC blower  running all the time in the front of the classroom. If I was going to be there permanently I would at the least turn the classroom around, and see if they couldn't change the blower from blast to coast.  It really helps to know about it and utilize good classroom management techniques to help everyone do better. I get some help on my insurance with the aids so haven't gone after the U.S. Navy and Alaska Marine Highway System for $. Thanks, Max

i have a 27 inch long by 3 inch diameter turned out muff on my savage now and it's loud and kinda deep but i went and ordered a 16 inch long by 2 inch diameter tapered cut muff to put on it and i will see what sounds better i have heard that those 2 inch tapered muff's are pretty similar to the sportster mufflers and will make the savage sound pretty good but we will soon find out .

Love my supertrapp too!
And who gives a crap about High Dollar sound?
It's that old Gold Star sound