When our red-sensitive nerves in our eyes cannot respond to light properly this will result in color blindness - b.
When either of the three light-sensitive nerves in our nerve tracts; either green, red or blue, we become to color blind for a certain spectrum of light from nature.
Sound waves are both compressional and longitudinal, (although we frequently draw them as transverse waves).
Longitudinal waves are where the particles of matter collide into one another, pushing them into the next and then oscillating back. This is how sound travels. This is also why sound can only travel through a medium, it cannot travel through a vacuum, as is shown here:
