effect of non-linearities of air on sound reproduction

[tsiros]

Is there any merit in taking into consideration the fact that air is a non linear medium?

 

[DF96]

When designing a high power horn loudspeaker, perhaps yes. Elsewhere, probably not.

 

[tvrgeek]

Air's non-linearity is an issue to understand, but there is nothing to do about it in designing loudspeaker cabinets. If it means anything, it reminds you that we should not spend our time on .1% problems when there are 1% problems we can't do anything about.

 

[PlasticIsGood]

What non-linearity? Pressure v volume?

Other than in loudspeaker design, what problems arise? It's not like we can get rid of it...that wouldn't be hi-fi.

 

[jcx]

the linear/perfectly reversable model of air compresion/expansion in sound wave propagation is violated when thermal energy leaks by diffusion from the compression peaks

this becomes a bigger problem at higher SPL - can account for single digit % distortion in compression drivers - worse with low flare rates so there are more wavelengths in the narrow high pressure peak horn throat

also can be measurable in giant PA arrays for outdoor concerts, stadiums


seldom a 1st order probelm with domestic drivers, home listening SPL

 

[PlasticIsGood]

OK, thanks. Presumably related to peak pressure and frequency. I guess we want adiabatic, not isothermal?

I suppose humidity complicates the issue considerably. Is sound from speakers visible in mist? I don't think I've ever been to an outdoor concert in fog.

 

[kelticwizard]

Didn't Small write something that the volume of the loudspeaker cabinet should be more than 10 times the volume displacement of the loudspeaker, (Vd), or nonlinearities kick in?

Also, I do remember reading of an Infinity loudspeaker-several woofers in a vertical array-where the top SPL was limited by that factor.

 

[tvrgeek]

About that. But proper alignment also is usually much larger, so not an issue. Maybe it helps as I prefer low Q sealed subs. I target .5.

 

[Wavebourn]

Air non-linearities create distortions of low order, and sound as if increased loudness.

Bose speakers always seem to sound louder, right?