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Can air pressure/elevation/air temperature affect driver performance?

post #1 of 16
Thread Starter 
I guess the above question would apply to speakers and open-type headphones specifically, but what are your theories?
post #2 of 16
This has been answered in the "Does temperature affect detail" thread.
post #3 of 16
Thread Starter 
I felt that my question was different enough, in that the thread you mentioned deals with temperature alone, but not specifically the temperature of the air, or headphone driver, or amp.. Just listening in general.

I'm asking specifically whether the characteristics of the air (such as pressure, temperature) can affect a driver's ability to put sound out (for example, an elevated location could have air that is less dense, and hence allows the driver to move air with greater ease). This could be especially significant with larger drivers that need to move more air, such as subs and large woofers.. I haven't tested this theory but I imagine it could make a much greater difference than, say, cables.

Sorry if that was not clear in the original question..
post #4 of 16
Of course it does. Air density, temperature, humidity, and even electromagnetic conditions affect performance somewhat.

The type of driver you use will react differently, too. Not everything is dynamic - an electrostat uses the air itself as a dielectric. As the air changes the behavior of an electrostat changes, too. For an interesting discussion of the effects, read the Stereophile review of the Quad ESL-63. They experienced problems operating it at a high altitude.

Don't forget your physiologic variables, too. The time of day, your frame of mind, blood pressure, and much else change how you hear things. You also get minute changes depending on how close you are to a radio station or cell tower, solar flares and even cosmic background radiation from the Universe itself. There's an unending list of things that make a difference.

Which is also a big part of the reason I dismiss cables and tweaks. Not to start a flame war, but there's a multitude of stuff that affects the final result, much of which we have zero control over. You could build a setup inside a Faraday cage in a salt mine, but even then what you ate for lunch might change your blood pressure and throw off what you're hearing. Or just being a month or two older will slightly change your hearing.

There are so many variables that, to me, it isn't worth splitting hairs over the geometry of a cable. The only way to keep from obsessing over infinitesimal differences is to accept that there are differences and there's nothing you can do to correct all of them. And, most importantly, that it doesn't really matter anyway.
post #5 of 16
Of course it does!
Temperature, humidity, air pressure, .. effect the transducer. In cold weather most materials get stiffer, in warm weather metal expand, ...
post #6 of 16
Sure it does, but will you be able to notice the difference? probably not
post #7 of 16
Quote:
Originally Posted by taso89 View Post
I felt that my question was different enough, in that the thread you mentioned deals with temperature alone, but not specifically the temperature of the air, or headphone driver, or amp.. Just listening in general.

I'm asking specifically whether the characteristics of the air (such as pressure, temperature) can affect a driver's ability to put sound out (for example, an elevated location could have air that is less dense, and hence allows the driver to move air with greater ease). This could be especially significant with larger drivers that need to move more air, such as subs and large woofers.. I haven't tested this theory but I imagine it could make a much greater difference than, say, cables.

Sorry if that was not clear in the original question..
Ah I see what you mean. Interesting question. I'm certain there would be an effect, but I've never seen actual data about how big the effect would be though. I suspect mechanically damped dynamics would be more affected than electrically damped ones.
post #8 of 16
Quote:
Originally Posted by Uncle Erik View Post
Interesting post
Interesting. OT, but what does putting it in a salt mine do?
post #9 of 16
Quote:
Originally Posted by cegras View Post
Interesting. OT, but what does putting it in a salt mine do?
It doesn't have to be a salt mine; any place far underground will do. Those are the few places almost entirely immune to cosmic background radiation. Some scientific tests are run far below to ensure that the particles they're detecting come only from what they're testing. Deep mines also have very consistent temperature and humidity, too.

For those who don't think there's a difference from temperarure, have you played an instrument? I've spent many years in marching bands and orchestras. We always had to retune when going inside or outside, as well as during football games when the sun would set and the temperature would drop. Voicecoils, frames, etc. change size just like an instrument will.

It's always struck me as strange that some will spends hundreds, if not thousands, on cables, power conditioners and tweaks while letting the temperature vary in their listening rooms. A ten degree difference should make a measurable difference. The logical thing to do would be to heavily insulate the room while equipping a thermostat to keep the room at an exact temperature.

I think it's better just to accept the small variables (including the sound difference between copper and silver if, indeed, there is one) as ones you cannot control, then put your time and money to more productive use. That would include listening to music.
post #10 of 16
Have you ever taken your dynamic headphones on the airplane?

They sound thin at that pressure and it is the reason why I only use IEM's up there. I put them in near the beginning of the flight and keep them in the whole way through. Maintains the same air pressure and the sound doesn't thin out as much. Plus, you forgo the whole popping of the ears problem. Popping ears for some of us is extremely painful.

You will also fine that you need much more volume, even when you have some attenuation from closed headphones. It is just harder for the diaphragm to move with more pressure.
post #11 of 16
Quote:
Originally Posted by -=Germania=- View Post
Have you ever taken your dynamic headphones on the airplane?

They sound thin at that pressure and it is the reason why I only use IEM's up there. I put them in near the beginning of the flight and keep them in the whole way through. Maintains the same air pressure and the sound doesn't thin out as much. Plus, you forgo the whole popping of the ears problem. Popping ears for some of us is extremely painful.

You will also fine that you need much more volume, even when you have some attenuation from closed headphones. It is just harder for the diaphragm to move with more pressure.

I don't even know where to begin explaining how factually vacuous this is.

The airspaces in your head are interconnected, it's the reason, for example, why you can purposefully increase interior pressure by blowing through your nose while its pegged. If you push an IEM into your ear, then for a brief period that airspace between the IEM and your eardrum is going to be marginally higher in pressure than the outside. Very quickly, equalibrium is achieved though, leaving that airspace the same as the current atmospheric pressure. If this were not the case then your music with IEMs would always have that funky odd sound that you get when you decrease your airspaces pressure and cause your eardram to bend inwards. It's no different if you're on or off an aircraft at altitude, equalibrium is still achieved, so your psudoscientific preservation of ground air pressure by putting your earphone in before you take off in order to keep a little pocket of ground level pressure for optimal conditions for the transducer is nonsense.

You'll need more volume if you've got some attenuation in a noisy environment like an aircraft certainly, but this is no different than walking along the street past roadworks, relative sound pressure has to be increased in order to maintain the same percieved different over ambient noise. If the aircraft ran silently, you wouldn't need that extra volume irrespective of the cabin pressure difference to ground level. The issue here is ambient noise, not atmospheric pressure.

It is harder for a diaphram to move against something denser certainly, its why we can swim in water but not through aluminium. This being the case, why do you want to preserve that imaginary higher density air pocket in your ear canal? Surely this would make it harder for the driver to move? I also fail to see why low frequency sound energy would be more affected by a slightly thinner atmospheric pressure than other frequencies.
post #12 of 16
For me - it is not just the sound, but the fact that my ears do not pop.
I have had ear surgeries and it makes me very sensitive to airplane flights. It is also something which I have to be extremely careful because these surgeries do make your eardrum more likely to tear than a normal person (scar tissue and all)
If I put my Customs in it is very hard for them to squeeze in more. Maybe it just slows the equalization process, but my ears never pop when I have them in. They also sound much fuller than my other headphones in the air (keep in mind that this was tested many times around Christmas time when I had 4 flights where the CD1000 and ESW9 were used in addition). My dad's ANC7's on ground sound bassy to my ears on the ground, but up in the skies sound more neutral.

What would be the reason that the bass goes down substantially up in the skies other than the pressure?

I know that the science doesn't make sense, but I would be interested in hearing other people's experience and some scientific evidence.

This article might allude to there being something with the SPL because of the relative difference in the pressure while up in the air. Potentially needing more power to get the same perceived sound level and it would interact like someone listening to things in lower volume and only hearing the middle frequencies. But I can't find anything in my 5 min long search directly relating anything with freq. response and pressure levels.
SOUND LEVELS
post #13 of 16
Quote:
Originally Posted by -=Germania=- View Post
For me - it is not just the sound, but the fact that my ears do not pop.
/snip
Yah, was just about to say the same thing. Ears are the main things affected by pressure etc.
My ears dont pop anymore either (and I suspect that one has mroe pressure than the other) so I'm planning on seeing an ENT. I know how you feel man
edit: Btw, if you see the GP you can tell him your ears dont pop and he'll probably recomend a spray like rhinocort (sp). I was on it for a bit and my ears dont pop, but the "fullness" of ear feeling is gone. There are other medicines like demazin (sp) which open the vessels around the ear and allow the drum to relax a little (and the sinus) and allow passing of mucus/air through the ear drum easier. Both are safe to use even if you have no other conditions.
Anyway, as for the science, i'll have a stab.
Your ear has a locked pressure inside it (that will dissipate over time, but not quickly such as ascending in a plane). The ear drum will stretch outwards (hence the pain) because the opposing pressures must approach equilibrium via tension in the drum. "Bass" requires a lot of movement by air/objects/etc because of its low frequency and thus large wavelength, and is produced in the outside frequency environment (meaning that it will be produced at a lower pressure than inside your ear) and will not be able to make the drum fluctuate as much - reducing the impact etc of the bass as it ventures into the inner ear. As for other sounds, I think theyre all quieter, but the higher pitches require less air movement for the same "volume" of sound.
as for other sounds being quieter, sound sends vibrations through particles which are tranferred through contact and/or emition (often both). Since theres a longer time between contact in low pressure areas theres a much larger amount of time (relatively speaking) for the sound to dissipate (or emit to decay) before contact (the main cause of transferrance) occurs.
Anyway, My 2 cents. 90% sure its correct, but soemone can correct me if they have the authority on the matter
bit lazy to explain better, but I'm quite sure thats it.
edit:: as for drivers being affected, I think they would probably be the least affected part of the sound chain from phone to brain. Second most would be the sound produced by the driver (which is due to the air around it), not the driver itself being affected. However, IMO headphone drivers will be affected by temperature because of thermodynamics, which would decrease the efficiency of the whole phone (as temperature increases). Energy lost would probably be through noise, so I dont really pay much attention to SNT values


EDIT: rethinking this doesnt sound all that right (more imperfect collisions would decrease volume as well, but probably not as much).
post #14 of 16
May I bump an old thread? Currently I'm up in the mountains of Japan Alps for a little stargazing for 2 nights. I've got a hybrid IEM with me. In Tokyo which is pretty much sea pressure the IEM has quite extended highs and decently tight bass, etc. Up here in the mountains (I'm only 1450m high but enough to make my bag of crisps & Ritz bloat like balloons), I felt the IEMs sounded somewhat more sibilant & the bass a little thinner but not as great a change as the trebles.

Alternatively I could be having 2 consecutive bad ear days?

I have general science knowledge but not enough to know its application in the audiophile world. Any comments are welcome.
post #15 of 16

Very interesting....
 

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