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Q & A: Can we ever see sound?

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Most recent answer: 03/24/2014
Q:
What is the relationship between sound and light? Theoretically (impractically) if the frequency of a sound were to be indefinitely increased would it eventually become visible? Thank you
- TRON
A:

Dear TRON,

First of all, cool name. Second of all, cool question!

Your thinking is clever and you are right that light and sound are both manifestations of waves. However, "sound" is what we perceive when our ears detect differences in the pressure of a medium surrounding us (air, water, etc.). A "sound" wave in air is exactly the same thing as a "pressure" wave. A light wave, on the other hand, is a completely different kind of wave-like phenomenon. Light waves are more precisely termed as "electromagnetic waves" which are actually oscillating electric and magnetic fields. See the diagram below:


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The way we "see" light--(a very small portion of the electromagnetic spectrum [see below])--is with the cone and rod cells in our eyes. These cells can react to the electromagnetic radiation of the visible spectrum and tell our brain what frequency the detected light is. The cumulative signals from these cells give our brain enough information to create the incredible sense of vision.

Electromagnetic spectrum:

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Thus, because sound waves have nothing to do with the electromagnetic radiation which our eyes are equipped to detect, we will never be able to "see" sound directly.

Having said all of that, there are certain people who do have a fascinating condition called which causes different senses to intermingle with each other. For instance, some people taste certain things upon hearing certain words and other people might see numbers as having different colors or personalities. A person with synaesthesia might see the number 9 as being menacing or red. Someone else might taste cheesecake upon hearing the word "taxi". Someone with synaesthesia might "see sound" but only because of weird neural crossovers in their brain. Each person with synaesthesia experiences this phenomenon in their own unique way.

I hope this answer helps!

Sincerely,
STAR WARS

Ok, I mean John.

p.s. In solids, you can have different types of sound, including transverse optical modes, which do have something in common with light, since they include an oscillating electrical field. However, their frequencies are all much less than the visible range. That's because in solids the sound waves describe the displacements of atoms. They can't have wavelengths less than the spacing between the atoms, so that rules out very high frequencies. Mike W.
 


(published on 02/14/2011)

Follow-Up #1: reader help

Q:
Hey guys, Whats goin on? I hope everyone is doing alright. I just wanted to let you know that The link pointing to the Electromagnetic spectrum : http://www.antonine-education.co.uk/physics_gcse/Unit_1/Topic_5/em_spectrum.jpg is no longer available. I have found the image in question by using the Wayback Machine. The link to the picture is http://web.archive.org/web/20120113145709/http://www.antonine-education.co.uk/physics_gcse/Unit_1/Topic_5/em_spectrum.jpg Just thought I would let you guys know. Have a wonderful day.
- Chris Laughlin (age 28)
Foxfire NC, USA
A:

Thanks, I put in the working link you sent.

Mike W.


(published on 03/24/2014)

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