Understanding the Basics of Sound
This is part 1 of a multipart series of articles that will provide a solid understanding of the principles of sound and acoustics as it relates to design and construction of both public and private spaces.Parts2-5 will cover Decibels, STC Ratings, Soundproofing and Room Acoustics.
A basic understanding of sound is important for the proper planning and design of any room or public space. If you have experienced not being able to clearly understand a speaker at an event or gathering or maybe attending a classical concert only to be distracted by poor sound sonus complete reviews quality you understand what I will be referring to. Sound and acoustics can be a very complex subject to dig into. My intent is not to make you an expert but to give you knowledge that will be useful for the purpose of designing your theater or listening room.
Quick Point # 1
Air is considered an elastic medium. This means that air molecules will expand and contract.
Sound energy radiates from the source and travels through air in waves. A good example would be to throw a rock into a pond and watch the ripples of water expand from the contact point.
Sound Waves travel by causing a chain reaction of the air molecules. The increased air pressure created from the source expands the surrounding air molecules. The air molecules collide with neighboring air molecules transferring the energy much like the old 5-ball pendulum desk ornament.
Visualize a forest. As the wind blows across the tree tops the branches move in the direction of the wind returning to their original position as the wind passes, never moving from their rooted location.
All of this happens with incredible speed and is completely invisible to the human eye. This reaction is repeated until the energy of the sound wave fades. As the waves travel through air they will gradually loose energy / intensity.
An example would be;
2x the distance = 1/4 the intensity
4x the distance = 1/16 the intensity
Sound Waves travel through air at sea level @ 1130 feet per second. Sound will travel faster in water or metal, than through air. The denser a medium the faster it will travel through it.
So that will give you an idea of how sound travels, but how do we hear it, you may ask?
On the receiving side our ears are design like to collect sound waves. The waves are transformed by the inner ear to electrical signals, and then passed to the brain for processing. Our brains do all the tough work transforming the sound waves into the wonderful sounds we hear.