Catch a Wave: Understanding How Sound Works

Posted by PinPoint Mounts on 10/2/2014 to General

When we sit down in our comfy chairs to watch a movie, or listen to our favorite music, we usually don't put a lot of thought into the mechanical process that creates the pictures we see or the sounds we hear. We simply kick back, relax, and let those glorious waves wash over us. Well, in the interests of furthering our appreciation of the things we enjoy, PinPoint Mounts is pleased to present a two-part blog series on understanding what goes into creating the audio and video we all know and love, and how our bodies and minds process that information. We'll take a look at the audio side today, with the video segment slated for next week.

How Sound is Produced

Every sound you hear, from the ticking of the clock on your wall to Mozart's most complex symphony, starts with vibration. The tick of the clock creates a single vibration, while the symphony is comprised of literally thousands of vibrations. The way that those vibrations travel from the material creating the vibration to your ears for processing is called a sound wave. The sound waves travel through the air, and are affected by everything in their path, until they reach our ears.

All Sound Waves Are Not Created Equal

Every sound wave that reaches your ears is a type of mechanical wave known as a longitudinal wave. They have peaks or crests at the top end, and troughs or valleys at the low end. The height of the peaks and the depths of the troughs is what determines amplitude, which basically equates to the volume we hear. The distance between the peaks or troughs is known as the frequency, and that is what determines the type of sound that we hear. Sound wave frequencies are measured in hertz, with one hertz being equal to a sound wave making one cycle through both peak and trough in one second. The higher the frequency, the higher the hertz. Sound waves are usually broken down into three groups:

Subsonic - All frequencies under 25 hertz fall into this category. In most cases, these frequencies are too low for the human ear to capture and process.

Audible - Frequencies ranging between 25 hertz to 18 kilohertz, this group contains all of the sound waves that fall into our auditory perception range.

Ultrasonic - Any frequency above 18 kilohertz is considered ultrasonic, and humans can't hear them. Dogs and some other animals can however. When you blow on a dog whistle and hear nothing, but your dog starts freaking out? Yep, those are ultrasonic sound waves at work.

Welcome to the Ear

When you look at the human ear, it is a nearly perfect example of a wave-funneling system. The sound wave hits the ear, travels through the ear canal and strikes our eardrum, which is a thin, tightly stretched membrane that is hyper-sensitive to vibrations. The eardrum processes those vibrations, converting them to electrical signals for the brain, which converts interprets those electrical signals into sound.

Simple, right? The next time you crank up your favorite CD, think about how all of those waves are traveling from your speakers to your ears and marvel at the engineering feat involved. Or, better yet, just sit back, relax and enjoy the music!