Audibility of distortion in horns!

[dewardh]

the lowest mode in my home theater is 30 Hz. How can a car be lower than a room?

That's as silly as the "you can't have low bass in a small room" argument, and wrong for the same reason.

Anyway, it's not a "mode", it's a cavity (Helmholtz) resonance. Entirely different things.

 

[myhrrhleine]

Hey Earl (and others). Do you remember how cars from 40 years ago and earlier didn't buffet? For years I drive a 1960's Buick and an old Dodge they never had that horrible oscillation. Why?

1. Bad aerodynamics. The wind didn't cling to the body.
2. Vent windows! How I loved vent windows. Drive down the road at 70 mph with no turbulence inside the car. Just a cool breeze.

It took me years to figure out why people would drive around with the car windows up, even on a beautiful day. No vent windows, that's why. A great loss to the automobile.

Oh yeah, and no way it's 0.01Hz. 300x that high, maybe. A horrible sound or sensation. Yuck.

As far as .01 Hz I was referring to the change in pressure as an airplane climbs or descends. The change in pressure is very slow as the plane goes up and down and I can sense this with my ears. Also a car going up or down a hill or even an elevator going up or down.
I imagine not everyone notices this or even is able to sense this.

As far as car buffeting, I would think it is the difference in mass.
the heavy cars of yesteryear did not get buffeted very much, but modern light weight cars do.

 

[Pano]

Ah, OK, Thanks. I descend 1600 feet every morning to go to work, then back up 1600 feet to come home. I certainly feel that in my ears. 🙂 Takes about 5-10 minutes to change level, depending on which road I choose.

 

[myhrrhleine]

Ah, then you "hear" it also.
That is a good example, 5-10 minutes is a very low frequency
But as I said there is virtually no meaningful information there.

 

[FrankWW]

That's as silly as the "you can't have low bass in a small room" argument, and wrong for the same reason.

Anyway, it's not a "mode", it's a cavity (Helmholtz) resonance. Entirely different things.

It's what Earl told you: you hear the modulation of the cavity resonance.

Roughness - fluctuation strength | Sound Quality | Acoustics Research Centre | School of Computing, Science & Engineering | University of Salford, Manchester

 

[whgeiger]

Answer

Yes, that is a correct application of the term.

PS. for those who think that the resonance of a car is very low consider that the lowest mode in my home theater is 30 Hz. How can a car be lower than a room?

The pulsations generated by say a 70 MPH air flow that is entering and leaving the 0occupant cavity of a moving vehicle with open window(s) bears little resemblance to the conditions present in your home theater. WHG

 

[turk 182]

well this thread has gone off the rails.(and is wandering through the forest)

at least the question has been somewhat discussed and some areas for reducing the audibility of distortion in horns has been covered.