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View Full Version : It is the same or is it? Questions about sound, vision and beer [separately]

komolono
12-29-2010, 12:13 PM
We consider 440Hz and 220Hz the same - A4 and A3 notes to be specific about it. I suppose that is because every other peak of the higher "A" resonates with the lower note. Well, I could be wrong because note D3 at 146Hz could be considered the same by multiplying it by three. Who knows? If we could see a little wider spectrum, could we see many greens and reds etc?

Now, if you place a can of beer outside your car and drive very fast, your beer gets cooled nicely. But try it outside a space shuttle. Well, it doesn't work - why?
(a Homer WHYYYYYYYYYYY actually)

ZenBeam
12-29-2010, 01:46 PM
Now, if you place a can of beer outside your car and drive very fast, your beer gets cooled nicely. But try it outside a space shuttle. Well, it doesn't work - why?:dubious: It worked for me....

ETA: Well, you need to be in orbit, not sitting on the launch pad.

12-29-2010, 02:04 PM
nevermind

Chessic Sense
12-29-2010, 02:14 PM
We consider 440Hz and 220Hz the same - A4 and A3 notes to be specific about it. I suppose that is because every other peak of the higher "A" resonates with the lower note. Well, I could be wrong because note D3 at 146Hz could be considered the same by multiplying it by three. Who knows? If we could see a little wider spectrum, could we see many greens and reds etc?

Now, if you place a can of beer outside your car and drive very fast, your beer gets cooled nicely. But try it outside a space shuttle. Well, it doesn't work - why?
(a Homer WHYYYYYYYYYYY actually)

On sound: We don't perceive those sounds as the same. They sound distinctly different. That is, if I played a tone at 440Hz and one at 220Hz, you could tell me which was which, every time without fail. What you mean is that they're harmonious sounds, which is just a result of the periods being simple ratios. The hairs in your cochlea flex at the same time, in rhythm, so it sounds "smooth". With different tones, the hairs flex at different strengths and times, out of rhythm, so it sounds dischordant.

On light: Doubtful. Light frequency is detected by different retinal cells. Those tell our optic nerve what color we're seeing. I see no reason why, if we had more specialized cells, the nerve would encode different frequencies as the same thing.

On beer: Conduction vs. radiation. In the air, heat is swept away quickly. In space, there's nothing to conduct the heat away. You have to wait for it to radiate away. I wonder if there's a pressure difference around the beer can in air that would cause a net drop in pressure and thus lower the average temperature of the air in contact with the can...

Ximenean
12-29-2010, 02:24 PM
We don't consider 440Hz and 220Hz to be the same, exactly. It's just that when one frequency is double that of another the two notes are so consonant, i.e. they sound so pleasing together, that they almost kinda feel like the same note. Your example of 146Hz compared to 440Hz is closely related to the interval known as the perfect fifth, which is considered the next-most consonant interval after the octave. The octave is a ratio of 2:1, the perfect fifth is 3:2. The simpler the ratio (i.e. the smaller the numbers in it), the more often the peaks coincide, and the more consonant the interval is.

komolono
12-29-2010, 02:42 PM
On beer: Conduction vs. radiation. In the air, heat is swept away quickly. In space, there's nothing to conduct the heat away.

I meant a landing shuttle which heats up a little:smack:.

AnalogSignal
12-30-2010, 07:45 PM
We consider 440Hz and 220Hz the same - A4 and A3 notes to be specific about it. I suppose that is because every other peak of the higher "A" resonates with the lower note. Well, I could be wrong because note D3 at 146Hz could be considered the same by multiplying it by three. Who knows? If we could see a little wider spectrum, could we see many greens and reds etc?

When you hit A3 on the piano, it is not a pure sine wave; there are also a series of overtones generated. The strongest overtone is the octave, A4 (220Hz * 2). The next overtone is the fifth (220Hz*3). Then comes the fourth (220Hz * 4). And so on.

Overtones not only explain the harmonic equivalence of A4 and A3 but also why fifths and fourths sound so consonant to the fundamental pitch.