Sounds travel through waves, and these waves are made by vibrating an object, whether vocal cords or drums, according to the University of Rhode Island. Moving the object in one direction compresses the air in front of it. The pressure differences in the air move away from the object, creating sound waves.
The movement of these air molecules creates a series of compressions and expansions that make up the sound waves. Sound waves travel in straight lines similar to light. But also in the same manner as light, sound can be affected by reflection, deflection of the path of a wave by a boundary, refraction and bending and scattering, when the path of the wave is broken. An easy test to see how sound waves are created is performed by placing one's index and middle fingers on the middle of the neck. The person should vary the way he says words in terms of volume. The vocal cords are vibrating as the sounds are produced. The unit to measure sound is a decibel, or dB. Decibels are measured exponentially. For example, total silence is about 0 dB; a sound 10 times more powerful is 10 dB, 100 times is 20 dB, 1,000 is 30 dB and so forth. Sounds above 85 dB could cause hearing loss.