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Temperature affecting detail level

post #1 of 24
Thread Starter 
Last night, I decided to go out for a walk. Stuck my DAP in my pocket and my headphones on my head and walked out into the frozen night. Temperature was about 24 deg F. Turned the player to Beethoven's Ninth Symphony, one of my favorite musical pieces.

As the second movement came on, I started to notice a change in the detail level of my headphones. It seems the cold made them more detailed. I could hear members of the orchestra shifting their weight, tapping their feet, and turning the pages of their music. I could hear what sounded like a percussionist keeping time with the music by tapping his drumsticks on his hands. I could hear the woodwind section breathing.

As I returned home, the third movement was coming on. As my headphones and DAP defrosted, I heard the sound return to its normal detail, still crystal clear, but lacking all the definition I had heard outside.

Has anyone else experienced such a phenomenon? I'm hoping this wasn't just in my head, if it was real, it could be very useful knowledge.

I'll try again tomorrow with a different piece and report my findings.
If anyone else wants to try it and report their findings, I would appreciate it
post #2 of 24
It might not be entirely your gear - your body changes with the temperature, too.

Also reminds me of the years I spent in various marching bands. We always had to retune our instruments with temperature changes. I don't know how much effect there is on hi-fi gear, but a few degrees north or south will send an instrument sharp or flat.
post #3 of 24
yes Uncle, I was going to say it might be the fresh air on your brain, well I guess I just did. Must be the fresh air.
post #4 of 24
Room temperature affect home systems
(the heating factor).
It should be the same with portable system, in a lesser way.
post #5 of 24
One possible explanation is that the electrical properties of silicon vary considerably with temperature. As the temperature lowers, the level of background or leak current present in a transistor decreases. This is why the very sensitive CCDs used in microscopy or astronomy are usually cooled to very low temperatures, so that they can detect even single photons striking the sensor.

It is possible that the cold temperatures was decreasing the level of background noise in the system thus allowing you to hear more detail.

More likely though is that it was just psychological and you just thought you heard more sound. Going for a walk in the evening maybe put you in a different mood and you thought you were hearing more. You could try freezing your equipment and seeing if it made the same difference (keep the equipment in the freezer and just run the headphone wire outside or something like that).

Ruahrc
post #6 of 24
o_O Interesting post...

I may have to try this with my whole room. As long as I keep the snow out, the winter in Ann Arbor should do the job... The only thing I'm worried about is the condensation that may happen.

So hmm....
post #7 of 24
Wow a fellow ann-arborer! You're right about this MI winter being cold enough...

In the case of small equipment like a portable amp, you could freeze it and while its cold put it in a zip-tight plastic bag (preferrably do this in the freezer so you get a bag ful of cold air too). The cold air inside the bag does not hold much moisture and thus when it warms up there will not be any condensation inside the bag. It will form on the outside of the bag though as the warm, moist room air has enough moisture on it to condense on the bag.

This same technique is used when bringing camera gear in and out of the cold as condensation on the lens elements is generally not preferred.

Alternatively when warming up the equipment, wrap it in a cloth so there is little air-equipment contact and let it return to room temp slowly.

Ruahrc
post #8 of 24
Could it be better hp performance with less humidity and cooler air?
post #9 of 24
Thread Starter 
Well, the temperature here tonight is above freezing, so I am not able to recreate the conditions.

However, in the name of science, I put my headphones in the freezer for about 1/2 hour. When I took them out and listened to them, I seemed to notice an increase in detail over room temperature, though not as great as last night.
I'm a little afraid of freezing my DAP because it has a permanent battery, and it needs to last a little longer than originally planned.
If someone has a player powered by AA or AAA batteries and wouldn't mind tossing it in the freezer for a while, the results of such an experiment would be most helpful in isolating the variables
post #10 of 24
Sound gets 0,6m/s slower per one degree celcius drop. At 0 degree celcius the sound has a speed of 331,3m/s, compared to 343m/s at 20 degree celcius.

In terms of frequency-range, this will effect the sinewaves, especially those with high periodic-swings (upper freqs). A sinewave with 15 000hz will do 15 000 swings per second. Ergo, it will swing 150 periods per millisecond. Frequencies around 1000hz will swing 10 times per millisecond.

Now, the fact that temperature will affect how FAST the sound travel, you will be able to distinguish (I think) each periodic swing with more precision due to the fact that your cochlea gets less sound-information per millisecond. The same amount of detail is provided, but the temperature allows the brain to process it slower.

If you're using earbuds or plugs, this will have no effect, becasue the temperature will remain quite warm anyway due to isolation. Open headphones will leak more warmth and therefore reduce speed of sound.

In orchestras, there are many different instruments with chambers, tubes and such. This will affect pitch drastically when the temperature drops, because all instruments has different tuning-needs. So, it's very common that orchestras sound out of tune when the weather is cold.

Back to the actual driver, though, I don't know anything about that, but I believe the cold weather will affect its efficiency at some point. Interesting thread btw!!
post #11 of 24
Let me chime in here... keep in mind that an instrument's pitch and tuning is affected by temperature because the instrument will overall expand or contract, raising or lowering its pitch respectively. Stringed instruments go out of tune because the different parts expand and contract and different rates and in different proportions. Headphones, however, do not resonate to produce sound like instruments do, in fact, most headphones are designed so that the parts don't resonate at all so that no frequencies are unpleasantly amplified.

Anyway, I'm willing to go along with it being a combination of various factors... change in body temperature (therefore a change in various biological processes within the body), change in driver qualities due to the cold. I'm not sure the solid state (MP3 player) aspect of the equation changes, though, although I do notice that my car radio really sounds bassless and weak when I first turn it on on a really cold morning and once the amp warms up, it sounds normal.
post #12 of 24
Would the wires be a few degrees cooler? If so, that should mean less impedance. Would less impedance have any effect?

What you said is interesting, alexpea, but I can't see how the speed of the air's sound can possibly affect what you hear, even if the speed were reduced to 1 mile an hour. Maybe i'm imagining it wrong, but this is what i imagine:

You have a device in the headphone that vibrates to create a vibration in the air. Say this vibrates at a rate of F times per second. For every 1 vibration, 1 pulse of air pressure is sent. The pulse (Pulse A) begins at spot X1 with a speed V. The next pulse (Pulse B) is sent when Pulse A reaches a spot X2.

Situation 1: V = 343.

Distance between Pulse A and Pulse B = 343 * (1/F) = 343 / F.
Suppose F = 10.
D = 34.3

Situation 2: V = 331.
D = 331 / 10 = 33.1


In both cases, the distance between Pulse A and Pulse B will remain constant as the two waves travel, because their speeds will be equal.

And in BOTH cases, the TIME it takes for a pulse to travel the distance D is equal. The time is simply:

1/F = 1/10 = 0.1 s

Alternate:
T = D / V = 33.1 / 331 = 0.1
T = D / V = 34.3 / 343 = 0.1

In other words, when velocity decreases, wavelength increases and the two cancel each other out so that frequency remains the same.

I think what matters is the TIME separation between each pulse, not the speed nor the distance between the pulses. The FIRST pulse will reach your ear slower, but every pulse after that will reach your ear the same number of times per second (frequency) as it would if the speed of the pulses were higher. So your ears would hear no difference no matter HOW much slower the waves were. Your brain wouldn't have any extra time to process each wave, because the time would be the same.

(i was a physics major for a couple years so i enjoy stuff like this lol)
post #13 of 24
Interesting discussion. I'm gonna throw my 2c at audio_noob, although not in that way. If the air was infinite temperature, it would translate air displacement on one side instantly to the other side (ie infinite speed of sound). Such a region of air could be modelled equally by removing it altogether (ie, no seperation of space exists between headphone and ear). Therefore the frequency at the ear would not be changed. Thus, in colder temperature, the frequency of sound arriving at the ear would be the same. It would just take longer to arrive.
post #14 of 24
audio_n00b: I think you're wrong. In your example, the speed of sound will not be affected bu temperature in any cases. I agree that the membran of the speaker isn't affected, but once the vibrations reach the air, it's not affected by the membran anymore. So, if the air is cool, then it will reduce the speed of sound. Simple as that! But at what degree is this noticeable at such short distance? I don't know, but it's certainly interesting to discuss

Take this for example:

15 000hz @ 20 degree celcius = 4,37 wave-pulses pr 1cm
15 000hz @ 0 degree celcius = 4,52 wave-pulses pr 1cm

What I don't really understand is whether the air affect the wave-lenght or not. If it does, this means that at 20 degree the wave-lenght is 22,80mm and at 0 degree it's 22,12mm. I think that the wave-lenghts are the same, but moving slower. If not, the speed of sound would be the same for both examples, and wave-lenghts separated them from each other.

As I said I don't know if it will be noticeable for the human ear, but the numbers are certainly speaking for themselves.
post #15 of 24
"Frozen night"

Perhaps you were walking in an extremely quiet neighborhood with no extraneous noise? Even a quiet household has it's own little bubble and squeaks.
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