A reference to what? I can discuss the science but you will have to ask audiophiles directly about their alternative notions about what is going on.
Sound is defined as a small/linear perturbation about a mean. If the perturbation is large enough for linearity to break down then we become unable to uniquely identify a part of the fluid motion as sound. This doesn't mean engineers can't kludge things a bit to handle distortion in specific limited circumstances but what is to be considered "sound" will be clear.
Boyles law is for an isothermal process but the sound waves in our rooms are much closer to adiabatic.
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I need to think some more when not so tired.
Agree with the andy19191 point, but how significant is it?
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A good question and I think the answer lies with the role played by scientific/engineering knowledge in how one reasons and goes about the hobby. Most posters on the forum don't possess the considerable amount of background technical knowledge that a competent trained engineer would use to reason about how to design speakers. When someone posts how to go about something using reasoning based on fundamental engineering knowledge it will carry significant weight for an engineer that possesses this knowledge but it won't for those without. They will have to check and test the likely truth in other less efficient ways and against other competing ideas that may lack a scientific basis but may be closer to what seems to be true among peers.
My experience has been that most don't welcome scientific/engineering reasoning when it conflicts with what they want from the hobby. It is hard to see much wrong with this if it enables one to have fun and achieve success on what one might perhaps think of as audiophile terms rather than scientific ones. It is a hobby after all and not an engineering job with success being measured by pleasure performing DIY and interacting with peers.
If you are referring to the sound waves inside the box (how the conversation started) then isn't it reasonable to conclude it's totally insignificant? If you are referring to sound waves in a room, then it seems irrelevant. I just wondered if there was something I'd missed about Boyle's law.
True at high variations of compression. But sound propagation is tiny variations in pressure. For these tiny variations in pressure, the process is adiabatic, and the air behaves as if it is linearly elastic.
Atmospheric pressure is 101,000 Pa. A variation of 1 Pa (0.001% variation) equates to about 90 dB.
Perhaps the non-linearities begin to matter at the diaphragm face of a very high output compression driver. But I can't imagine a direct radiator driver producing an SPL high enough for this to be a concern.
To further my point: A pressure variation of 0.1% (i.e. 101 Pa) would equate to an SPL of 130 dB. There is just no way that volumetric non-linearity is of any significance when the pressure is oscillating around 0.1%.
A 0.1% pressure oscillation will produce a 0.1% volume oscillation, for any practical or measurable purposes.
I refreshed my memory with this useful web page - - Sound Intensity and Sound Level | Physics
A 0.1% pressure oscillation will produce a 0.1% volume oscillation, for any practical or measurable purposes.
I refreshed my memory with this useful web page - - Sound Intensity and Sound Level | Physics
While true for most speakers, consider what's going on with a compression driver or inside a small sealed subwoofer.
Chris
As I have shared many times; I am a retired Engineer and Technician and former musician all. I understand the math and science; I also trust my own ears. Sometimes; the minor yet significant differences to me are likely to NOT be measurable to anyone with just home based equipment or technology. The human brain is an amazing thing; can't be outdone by technology IMO when it comes to music and audio (for what it is I'm after anyway). And so it goes; on and on...
That's because...(lean in close and listen intently for the secret wisdom)...THEY ARE NOT IN A BOX
Seriously, as @Zvu and others pointed out through the thread, the unboxed driver has a lot of effects that just won't happen in a box. Phase cancellation, rearward radiation reflected from the room, on and on. The "open baffle" thus is interpreted as an "open sound" that can be very nice. Maybe vaguely like the "open sound" of planar speakers. Speakers in a box just won't sound like that, they will sound different.
Impedance sweeps here, Mark: https://www.diyaudio.com/forums/multi-way/360015-box-sound-7.html#post6338825
Chris
Chris
Instinctually neither seem to be significant to me, but we need some modelling anf maths to verify that, or not.
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