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When I produce a 440hz signal is it in all conditions (air-pressure, medium or compositon of the athmosphere, on a mountain, on alien planets etc.) perceived as the same note? Assuming a human can survive in all those mentioned conditions of course.
I only ask about the frequency, which is the pitch. Not about other parameters of the tone.
The perception of a pitch is due to the frequency of vibration of the hairs in the cochlea (the spiral-shaped organ in the inner ear), which is, in turn, driven by the vibration of the eardrum. Anything that drives the eardrum at a given frequency, say 440 Hz, will be perceived as the same pitch, regardless of medium.
What the medium does affect, however, is the speed of sound (v), which determines the relationship between frequency (f) and wavelength (L) according to the equation v = f * L. The physical mechanisms of many instruments are such that they create a tone of a fixed wavelength rather than a fixed frequency. For example, an organ pipe will create a standing wave with a wavelength determined by the length of the pipe. If the pipe is tuned to produce 440 Hz at room temperature, than changing the temperature of the air -- or its humidity, density, or even completely changing the medium -- will cause the speed of sound to change. As a result, the frequency it produces will be different, and it will be perceived as a different pitch. Organ tuners are always careful to tune organs at room temperature, and if the organ is played at a different temperature, it may sound out of tune.
Incidentally, this is also why breathing helium creates such a funny sounding voice. The shape of the mouth and the tension of the vocal cords fix the wavelengths that are produced, but the lighter medium allows the sound waves to travel faster, so they have a higher frequency. When the waves exit your mouth into the "regular" atmosphere, they retain their frequency, and it is the wavelength that changes to accommodate the slower speed of sound.
If you can cause the tympanic membrane of a normal-hearing human to vibrate 440 times per second, they will "hear" the pitch we call A4. So, there are two ways to go with your question. A device that is designed to produce 440 Hz here on Earth is designed to cause normal earth air at normal air pressure to vibrate 440 times per second. In significantly denser air, that device will not be able to vibrate the medium as quickly as it's designed to do, and thus the pitch perceived will be lower. The opposite is true for lighter air. If there's no medium at all, such as empty space or a planet with no atmosphere or liquid, then there can be no sound.
However, another approach to the question is to assume the device is capable of vibrating any medium 440 times per second. If the device produces 440 Hz with respect to the medium, then the perceiver will hear an A4.
The difference in air pressure on various parts of the earth isn't large enough for major discrepancies, but you can hear how much lower pitch sounds when the medium is water.
It's worth noting that most pitched sound contains way more than a single frequency, so the more noticeable effect would probably be timbral, as higher overtones will be more able to excite a thicker medium.
For the sake on completeness, I will add that the relative speed between the generator of the sound and the observer will change the pitch, due to the Doppler effect.
In short: no. "The same note" is a musical concept, and playing 440Hz in a baroque concert with A=415Hz tuning will not be perceived as an A. As long as your question is about a "note", a musical concept, rather than an acoustical phenomenon, the answer is clearly "no". Even with an A=440Hz tuning, 440Hz might indicate a double-flatted B instead of A, again a different note (as notes have a role in scales).
Now if you are not talking about note but only perceived pitch as an acoustical rather than musical phenomenon, perceived pitch, like perceived color, depends on the backdrop. If you are talking in a helium atmosphere with others, your pitch perception and evaluation will adapt to their speaking voices.
