Let's Talk Shop

Sound better, look better

Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Navigating the world of acoustic foam can be overwhelming, with many technical terms to consider. To simplify your search for the right sound treatment solutions, Soundbox Depot has compiled this glossary of commonly used terms in the industry. Whether you're improving your studio's acoustics or exploring soundproofing options, this guide will help you understand the concepts and products better.

A

Acoustical Foam

Foam that is designed to attenuate or dampen vibrations and sound waves.

Acoustics

The branch of physics that studies the properties of sound such as mechanical waves, including vibration, sound, ultrasound, and infrasound.

Airborne Noise

Any sound that is transmitted through air, like music or speech.

Airflow

Amount of air that goes through a foam expressed in cubic feet per minute. Usually measured by drawing air through a 2”x2”x1” sample. Relevant because airflow influences the effectiveness of open-cell acoustic foam in sound absorption.

Attenuation

Attenuation is a damping of sound or more specifically, the gradual loss of intensity through a medium. When discussing acoustics, attenuation refers to a structure’s ability to limit sound transmission.

B

Baffle

An acoustic baffle is a device that reduces the strength of airborne sound. Usually hung from the ceiling, baffles will help to absorb sound, reducing echo and lowering reverberation time.

Bass Traps

An acoustic bass trap is a device that is designed to absorb low end frequencies that is often found in the corners of a given space.

C

Cell

You’ll see this used to describe both closed-cell or open-cell foam, which is crucial for acoustics. Known as a bubble, or pore. This word refers to the cavities left in a foam structure after the bubble walls have completely polymerized as well as solidified, or, in some cases of foam, curled back and fused into the boundary joints, forming the skeletal structure.

Closed-Cell

Closed cell is a property of foam where each cell or bubble is sealed off completely and has no connection to any of its neighboring cells. Since the cells are sealed, water and gas cannot be exchanged between cells.

Cloud

Similar to acoustic baffles, acoustic clouds are free-hanging absorption panels that are suspended from a ceiling. This allows them to absorb sound waves at two points.

Cross-Linking

This is the process of tying molecules together to form certain foam types. Useful for understanding the manufacturing process behind specific foam types.

D

Decibel

A unit of measurement used to describe how loud something is.

Density

The weight of foam; typically expressed as lbs/cubic foot. A key characteristic affecting sound absorption and foam performance.

Diffuse

To spread out over a large area and when it comes to acoustics, the scattering of sound waves, reducing the sense of localization.

Durability

How well and how long the foam retains its comfort, support, and shape over time or the longevity of acoustic foam panels.

E

Echo

An echo is created when sound reflects off a surface and back into a listener’s ear, noticeably with delay after the initial creation of sound. Echo is one of the most common acoustical problem that can be exacerbated by hard surfaces or large, open spaces.

F

Flame Retardant

Foam that has additives that allow it to be fire resistant, or burn slower than other materials. Relevant to safety concerns for acoustic foam used in studios or public spaces.

Flanking Sound

Sound that travels between two spaces indirectly. This can be sound traveling through vents to reach another room or even sound coming from down the hallway.

Flutter Echo

A flutter echo is an when sound is reflected off parallel surfaces, creating a rapid series of sound that reaches the listener. This is observed as “fluttering”.

Footfall

A form of impact noise that is created by walking. Footfall occurs when feet come in contact with a floor. Many people call this sound “footsteps”. This can be a common issue in many multi-floor apartment complexes, gymnasiums, and open spaced rooms.

Frequency

When discussing sound waves, frequency is the number of waves that occur in a selected duration or period. In terms of sound, generally frequency correlates to the pitch of a sound; low frequency sounds are usually lower in pitch while high frequency sounds are higher.

H

High Frequency

High frequency waves begin at around 2,000 Hz and go up into the kHz. These sounds come in variety of ways and are usually higher pitched sounds that can be described as “sheeny”.

I

IIC (Impact Isolation Class)

IIC ratings measure a floor’s ability to limit impact noise and vibration transfer. Like STC, the higher an IIC rating, the better a structure is at sound. Traditionally, an IIC of above 50 is required in many commercial spaces to limit footfall and impact noise.

Impact Noise

Impact noise occurs when one object hits another, generating sound that travels through a building. The impact of these two objects will create a structural vibration, which can travel through walls, floors, ceilings, doors, and windows.

Infrasound

Sound frequencies below 20 Hz that are a too low for humans to perceive.

K

K-Weighting

A frequency-weighting curve used in audio measurements to approximate human hearing sensitivity, particularly in loudness measurements. K-weighting is commonly used in broadcasting to measure perceived loudness and ensure consistent audio levels.

L

Low Frequency

Low frequency sound waves are waves around 500 Hz or lower. Of course, these are sounds are perceived as “lower” to the human ear. These frequencies are often felt as a “rumbling” sound as much as they are heard. Typically, these waves are heard in bass, 808s, and even some lower baritone voices.

M

Mid Frequency

Mid frequency sound waves are around 500 – 2,000 Hz. This frequency range can be described as having a tinny or horn like quality to it.

N

NRC (Noise Reduction Coefficient) Rating

NRC is an acronym for Nosie Reduction Coefficient and measures frequencies ranging between 250 – 2,000 Hz. It is a rating system that describes the average amount a material can absorb sound.

Ranging from 0.0 – 1, 0.0 being perfectly reflective, and 1 being perfectly absorptive, the formula used to determine NRC does not provide a percentage, however, so values can be greater than 1 (more attenuation).

Regardless, NRC ratings can roughly translate to the percentage of sound absorbed by an item. For example, a product with an NRC rating of 0.85 would absorb roughly 85% of the sound it encounters.

O

Open-Cell

A specific process that creates a foam that expands during the manufacturing phase. Open-cell foam is defined by cells that are not fully closed by walls, and are open to the surface. The primary characteristic is that water, air, or gas can pass through, much like a sponge. This type of foam is excellent for padding, cushioning, outdoor furniture, and applications where low compression is desired. Defines a primary foam type used in sound treatment for its air permeability and sound-absorbing qualities.

P

Peak Sound Pressure

The maximum instantaneous sound pressure level (SPL) experienced in a given sound wave. It is a critical measure in audio engineering and acoustics, especially when assessing the intensity of loud or impactful sounds.

Q

Q Factor (Quality Factor)

A measure of how selective a system is in amplifying or attenuating certain frequencies. In acoustics, the Q factor is often used to describe the sharpness of resonance in speakers, equalizers, or soundproofing materials. A higher Q indicates a narrower and more precise frequency range.

R

Resilience

Describes how foam regains its shape, relevant for long-term acoustic panel performance. An indicator of the surface elasticity or “springiness” of foam. See also, durability.

Resonance

The normal or natural mode of vibration of air through a foam or similar material. Relates to the behavior of sound waves through foam, a key concept in acoustics.

Reverberation

Defined as the persistence of a sound following its initial creation. Reverberation is created as sound reflects off surfaces and decays. Reverberation can be particularly bothersome when the initial source of sound stops, but the sound continues to build up and then decay over time as the sound is absorbed by objects within the space.

Reverberation Time

A measurement, in seconds, of the time it takes for a sound to “fade away” or decay in a closed space. For smaller rooms, reverberation time should typically be under a second, while larger rooms, such as auditoriums, should typically have a reverberation time up to 2 seconds.

S

Sound Absorption

The process by which sound waves are taken in (or absorbed) by an item or structure, as opposed to reflecting off that item. There is a loss of sound energy when sound waves encounter an absorbent material.

Sound Barrier

It is also known as noise barrier. It’s a material that can be placed on structures such as a walls, ceilings, or floors that will increase the STC rating of the structure. They are designed to limit the amount of sound transmission.

Sound Pressure

Occurs when pressure is created in a space in the presence of sound.

Soundproofing

Soundproofing is the process of preventing sound from traveling from a space to another. This is typically achieved by either blocking noise from entering a room or blocking sound from leaving the room. Simply put, making a room resistant to the passage of sound.

Sound Treatment

Sound treatment is the term used to refer to the application of absorption and diffusion technology in a space. Every room is different and how you approach treating the sound energy will depend on the space and the needs thereof.

STC (Sound Transmission Class) Rating

STC Rating is a numerical value indicating how well a structure is at reducing airborne sound transmission. STC is commonly used to rate walls, doors, windows, ceilings, and floors. For STC ratings, the higher the value, the better a structure is at reducing airborne sound. On average, a well soundproofed wall has an STC rating over 50.

U

Ultrasound

Sound frequencies above 20,000 Hz that are a too high for humans to perceive.

What Customers Are Sayin About Our Acoustics

⭐⭐⭐⭐⭐

I am converting a small bedroom in my basement to a voice over recording studio. I am putting these acoustic panels on the walls and they are of good quality and density I need.

Vern Ray Beachy

HAPPY CUSTOMER

⭐⭐⭐⭐⭐

Just what the doctor ordered. Best quality foam on the market.

Darian

HAPPY CUSTOMER

⭐⭐⭐⭐⭐

Very nice acoustic foam. It’s dense and did a great job absorbing sound in my studio. Great company!

JB

HAPPY CUSTOMER

⭐⭐⭐⭐⭐

I am converting a small bedroom in my basement to a voice over recording studio. I am putting these acoustic panels on the walls and they are of good quality and density I need.