Steve PMHMusic was a big part of my life growing up. When I was younger, I joined the school orchestra and was the first-chair cellist. It was a time filled with great memories.
Out of all those great memories, one thing in particular always stuck with me; our instruments sounded different depending on what room we were playing in.
In the classroom, our instruments projected sound well. At home, however, my cello sounded weak and hollow
I convinced myself that the reason was that I was practicing solo as opposed to being in a group. Now, I know it was all about the acoustics.
If sound theory piques your interest and you’re wondering about acoustics in music, this is one post you don’t want to miss!
Short answer: Acoustics in music deals with the production of sound by musical instruments. Likewise, it deals with how musical sounds are conveyed to the listener.
General Acoustics
Acoustics is the science of studying various types of sounds and their laws in nature. It’s why many experts consider acoustics to be a branch of physics.
In the past, acoustics used to be divided into two branches. The first is diacoustics, which is the study of refracted sounds and the medium through which they pass.
The second is called catacoustics. It’s the study of how sounds bounce off various surfaces, also known as the echo effect.
Nowadays, these two branches fall under the main study of acoustics in general. They’re studied side-by-side.
What Is Acoustics in Music?
The term acoustics comes from the Greek word akoustos, which means ‘heard.’ Acoustics in music studies both the perception and performance of music.
This branch of music theory takes the methods used in general acoustics and applies them to music.
Also referred to as musical acoustics, it consists of various attributes. Each of these attributes has certain parameters that we can calculate and analyze.
Here are just a few examples of musical acoustic attributes:
Sound Waves
Sound waves move through a medium via vibrations. These vibrations, or waves, start at ‘zero line,’ or silence. The wave rises above the zero line to show an increase in air pressure and sound is heard and you get a positive phase.
When the curve of the wave dips below the zero line, we feel a decrease of pressure and sound diminishes. This is called the negative phase.
Waves can combine and create ‘in phase,’ where sound waves increase dramatically. They can also merge and create what’s known as ‘out of phase.’ When this happens, it means that one phase is positive and the other is negative, causing the pressure to drop.
When sound waves interact with each other, they form a complex wave. Musical instruments are constantly creating complex waves, which is how they’re able to produce such distinctive and pleasing sounds.
Frequency
Frequency measures the speed of sound waves in Hertz (Hz). On average, a piano can create soundwaves ranging in frequency between 27.5 Hz up to 4186 Hz. The audible spectrum of the average human hearing is from about 20 Hz to 20 kHz.
Anything below 20 Hz is called subsonic. We can’t hear anything subsonic, but we can feel the sound waves within this range.
Ultrasonic is any sound wave that goes past 20 kHz. Our ears aren’t able to register anything over 20 kHz. Yet, there are certain animals and sound test equipment that can pick up on these frequencies.
Sound Pressure Level
Our ears are amazing instruments in and of themselves. They can register sounds that can fluctuate from highly soft to excruciatingly loud.
To measure sound pressure level (SPL), we use a sound level meter. It expresses the readings on a decibel scale (dB), named after Alexander Graham Bell.
The human ear can detect sounds as soft as 1 dB. Although, 3dB is the common level at which sound is discerned by the average listener.
Appropriate sound levels for normal conversation ranges between 60 and 65 dB. On a busy street, sound pressure levels can reach up to 85 dB.
Amplitude
Sounds can range from extremely loud to barely audible. This depends on the amount of energy being used to create vibration waves.
The bigger the energy, the greater the amplitude, and the louder the sound.
Amplitude is “the distance moved by a point on a vibrating body measured from its equilibrium.” Equilibrium is the ‘zero line’ on the sound wave scale and refers to complete silence.
Then, force is exerted on the vibrator. If the force is minimal, the amplitude will be minimal and the loudness of the sound itself will decrease.
The opposite is true as well. The greater the force exerted on any type of vibrator, the greater the amplitude.
How Room Design Impacts Acoustics in Music
The main feature of acoustics in music is how musical instruments generate sounds. A common way to classify these instruments is the way they vibrate.
Musical instruments are divided into three major categories: string, wind, and percussion. For each type of instrument, the player delivers a force to the primary vibrator. It can be a string, a plate, a bar, or a membrane, depending on which instrument is being played.
Yet, what many people tend to overlook is the acoustics of a room plays a large part in how these vibrations are heard. Different rooms create different acoustics. This is where acoustics in music intermingles with architectural acoustics.
While there may be multiple types of rooms that can go on our list, we decided to pick the three most common rooms. Each one of these rooms has a unique floor plan for optimal acoustics.
Even though their architectural design is different, they share some common characteristics. For one, they all need to be able to distribute sound equally.
Another thing they have in common is they should be equipped with suitable furnishings. These additions help limit background noises while enhancing the main sound source.
Open-Plan Rooms
Open-plan rooms are created with an extended design. They have open-plan corridors and general areas where sound moves freely.
The planning of an open-plan room depends on the following:
- Ceilings must have high absorption rates
- The design of furnishings
- The choice of floor surface
- The location of workstations
Hard Rooms
Hard rooms have little absorption qualities. They consist of walls and ceilings that reflect much of the sounds played in the room. As a result, hard rooms provide greater amplification and better acoustics.
Rooms with Absorbent Ceilings
One of the more common types of acoustic rooms is those with sound-absorbing ceilings. Many factors go into a room with a sound-absorbing ceiling.
These rooms depend on the location and type of the various furnishings. The shape of the room also plays a key role in the level of sound absorption and amplification.
How Is the Human Ear Affected By Acoustics?
Acoustics is all about sound waves, which only count if they’re able to reach the human ear. Our ears are made up of four basic parts. Each part allows us to hear a wide range of sounds as we go about our daily lives.
Read ahead to learn about how the shape of our ears manages acoustics and helps boost our perception of sound waves.
The Pinna
Known as the pinna, or the auricle, the outer ear is shaped like a funnel. It’s the first part of the ear that receives sound waves.
The pinna gathers sound energy in the form of waves. Then, it amplifies them and sends them inward to the next section of the ear.
This method of amplification localizes the sound source. It helps us determine the direction, frequency, and pitch of each sound.
The Auditory Canal
The auditory canal is a passageway that’s about one inch long. Even though it’s separate from the other parts of the ear, many experts still consider it as part of the outer ear.
The main function of the ear canal is to guide sound waves to the eardrum located in the middle ear.
The auditory canal also boosts the loudness of the sound waves for a clearer, more defined sound.
The Middle Ear
The middle ear traps in airwaves and controls their movements via the eardrum. Next, the eardrum takes the trapped air and moves it into the eustachian tube.
This tube is located behind the nasal cavity and connects the middle ear to the back of the throat. Its main job is to drain fluids from the ears. It also works to control the internal air pressure and equalize it with the atmospheric pressure outside the ear cavity.
The Inner Ear
The inner ear receives the airborne sound waves sent to it via the middle ear. It consists of water-like fluids encased in a tiny piece of solid bone called the cochlea.
The cochlea is coiled up like a seashell lined with millions of tiny hairs. These transmitters convert sound pressure patterns into electrochemical signals.
After that, the signals are sent to the brain via the auditory nerve. The brain, then, interprets these signals as sounds that we can recognize and perceive.
