Similarities
1. They are the basis of the two most important human senses
2. Each frequency is associated with a unique sensation (red or green, C or E)
3. There is a range outside which humans are not able to detect them (infrared and ultraviolet, infrasound and ultrasound)
Differences
1.-Sound is a longitudinal wave, light is a transversal wave (sound has no polarization, light do have it)
2.-Sound is a pressure wave, sound is a electromagnetic wave (sound needs matter to propagate, light can propagate in a vacuum)
3. From the human point of view, wavelength of sound is relatively large while wavelength of light is relatively small (diffraction of sound is stronger than diffraction of light, so sound can get around obstacles while light seems to travel in a straight line).
4. Two frequencies of sound are heard as separate components of a chord. Two frequencies of light are confused in a sensation similar to a third non-existent frequency (C,E and G are heard as the C major chord, red and green are seen as yellow)
5.-We are able to perceive the direction from which a sound come only in an unidimensional (horizontal) dimension. We are able to perceive the direction from which a light come in a bidimensional map (an image).
