Welcome to our Acoustics Glossary

Do you want to understand acoustics? At Studiospares, we understand that the world of acoustics can be very daunting and often hard to comprehend, with complex words that have even more complex meanings, leading to complex headaches… But don’t worry we’re here to help you shed some light on acoustics! 

Our goal is to break down the barrier to entry on acoustics so that anyone can understand these concepts. When you come to acoustically treat your space, you’ll understand what everything is and exactly what it’s doing! 



Absorption is the process by which sound energy is absorbed or taken in by materials, converting the sound energy into heat rather than reflecting it back into the environment.


Absorption coefficient (<)

The absorption coefficient (α) of a material indicates the amount of sound energy that is absorbed by the material when sound waves interact with it. It ranges from 0 (perfect reflection) to 1 (perfect absorption).


Acoustic Design

The intentional shaping of spaces, structures and materials to achieve desired sound characteristics. 


Acoustic Lens

A device or material designed to focus or disperse sound waves. 


Acoustic Panel

An acoustic panel is a specially designed surface that helps control sound reflections and echoes in a space. It is used to improve the acoustic quality of a room by reducing unwanted noise and enhancing clarity.


Acoustic treatment

Acoustic treatment involves the use of various materials and techniques to manage sound within a room or space. The goal is to control echoes, reflections, and other acoustic properties to create a more pleasant and controlled acoustic environment.



Acoustics is the branch of physics that deals with the study of sound, its production, transmission, effects, and behavior in different environments.


Air Gap

The space between a wall and an acoustic treatment material, influencing its effectiveness by allowing sound to be trapped or absorbed. 


A-Weighting (dBA)

A-weighting is a frequency response curve used to measure and show the perceived loudness of sounds, considering the sensitivity of the human ear to different frequencies. The measurement is given in decibels A-weighted (dBA).



Ambience is the overall sound quality and character of a particular environment or space. It concerns the background noise, reverberation, and acoustic properties that contribute to the way a place sounds.


Ambient Noise

Ambient noise is the background sound present in a particular environment. It includes all the normal sounds that are present in any space, such as traffic noise, HVAC systems, and other persistent sounds.



Attenuation is the reduction in the intensity or strength of sound waves as they travel through a medium. It can result from absorption, reflection, or the scattering of sound energy.



An audiogram is a graph that displays someone’s hearing sensitivity across various frequencies (measured in Hertz) and sound intensity levels (measured in decibels). It is used to diagnose hearing loss and assess the severity of impairment.


Anechoic Chamber

A room designed to absorb all sound, creating and environment without echoes or reverberation. 


Background noise

Background noise is the level of sound that is present in an environment even when no sound sources are on. It can include various ambient sounds that contribute to the overall acoustic environment.



A baffle is a physical barrier used to redirect or control the path of sound waves. It is often implemented to reduce echoes, control reflections, or create specific acoustic effects. They are normally hung from the ceiling.



Barriers are structures or materials used to block or reduce the movement of sound from one area to another. They can be physical walls, partitions, or specialized acoustic materials designed to prevent sound from escaping.


Bass Trap

A bass trap is an acoustic treatment aid designed to absorb low-frequency sound waves, particularly in the bass range. It helps to reduce mass bass buildup and improve overall sound quality in a room.


Boundary Effect

Changes in sound properties near room boundaries, influencing sound reflection and absorption. 


Ceiling cloud

A ceiling cloud is an acoustic treatment aid suspended from the ceiling of a room. It helps control sound reflections and echoes in the upper part of the space, improving its acoustic quality.


Cocktail Party Effect

The cocktail party effect refers to the ability to focus on and understand a conversation or hear a sound in a noisy environment, even when there are competing background sounds.



Coloration in acoustics refers to the reshaping of the natural sound characteristics of a space or audio signal because of the room’s acoustics or the equipment used. It can result in unwanted tonal changes or distortions.



Unwanted interference or bleeding of sound between different audio channels or systems. 



When a space is described as “dead” acoustically, it means that the room has very little or no sound reflections or reverberation. Sound energy is absorbed quickly, resulting in a lack of life in the environment.


Decay Rate (dB/sec)

Decay rate is a measure of how quickly sound energy reduces in a space after a sound source has stopped emitting sound. It is measured in decibels per second (dB/sec).


Decibel (dB)

The decibel is a unit used to measure the intensity or level of sound. It’s a logarithmic scale that demonstrates the ratio of a sound’s power to a reference level, normally the quietest sound a human ear can hear.



The scattering of sounds waves, often achieved through specially designed surfaces to create a more balanced acoustic environment. 


Diffuser/Scatter Plate

A panel with irregular surface patterns designed to scatter sound waves in various directions. 


Direct Sound

Sound waves traveling straight from the sound source to the listener without reflections or alterations. 


Exchange Rate

The exchange rate, when measuring noise exposure, tells us how long we’re allowed to be around loud noise before it can start causing harm. It’s like a rule that changes depending on how much louder or quieter the noise gets. People often use exchange rates of 3 decibels (dB) or 5 dB to figure this out.


Early Reflections

The first sound reflections reaching a listener, impacting the perception of sound quality. 



The ability of sound to bounce off surfaces and objects, affecting the perception of space and sound quality. 



Fiberglass is a type of material composed of thin glass fibers. It is often used in acoustic treatments due to its sound-absorbing properties and is found in products like acoustic panels and bass traps.



Flanking refers to the movement of sound around, rather than through, a barrier or acoustic treatment. It occurs when sound waves find paths of lesser resistance, bypassing the intended treatment measures.


Flutter Echo

Rapid, repetitive reflections of sound waves between parallel surfaces, causing an audible fluttering effect.



Frequency refers to the number of cycles or vibrations that a sound wave completes in a unit of time. It is measured in Hertz (Hz) and determines the pitch of sound.


Helmholtz Resonator

A device designed to absorb specific frequencies, consisting of an enclosed volume of air with an opening.


Hearing Conservation Program

A hearing conservation program is a workplace initiative aimed at preventing hearing loss among employees exposed to high noise levels. It typically includes measures such as noise monitoring, hearing protection, and employee education.


Hearing Protection

Hearing protection refers to devices such as earplugs or earmuffs that are worn to reduce the exposure of the ears to loud noises, preventing noise-induced hearing loss.


Hertz (Hz)

Hertz is the unit of measurement for frequency. One Hertz represents one cycle or vibration per second. It is used to calculate the pitch of sound waves and other periodic occurrences.


Impedance Matching

Matching the acoustic impedance between two mediums to minimize sound reflections.



Sound frequencies below the human hearing range, typically felt rather than heard.



Isolation is the prevention of sound traveling between two spaces. It involves using barriers and other methods to reduce the transfer of sound energy from one area to another.


Isolation Booth

A small, enclosed space designed to isolate sound, often used for recording purposes.



Leakage refers to the unintended escape or movement of sound through gaps, openings, or weak points in acoustic barriers or treatments. It can compromise the effectiveness of acoustic treatment.


Leq (Equivalent Noise Level)

Leq is a measurement of the continuous equivalent noise level over a specified period. It considers varying noise levels and provides a single value to represent the overall noise exposure.


Ln Statistical Noise Levels

Ln statistical noise levels represent the levels of noise that are exceeded for a certain percentage of time. For example, L10 represents the noise level exceeded for 10% of the time.



When a space is described as “live” it means that the room has significant sound reflections and longer reverberation times. Sound energy persists in the space for a noticeable duration.



The subjective perception of the intensity of sound.


Microperforated Panel

A panel with micro-sized perforations, enhancing absorption while maintaining aesthetic appearances.


Modal Resonance

Standing waves that form in a room due to specific dimensions, causing peaks and dips in specific frequencies.



Noise is unwanted or undesirable sound that disrupts the intended acoustic environment. It can include sounds from various sources, both natural and human-made.


Noise Criteria (NC)

This is a system used to classify the tolerable noise levels for different types of indoor spaces. It takes into consideration factors such as room usage and desired comfort levels.


Noise Induced Hearing Loss

This is a type of hearing impairment caused by prolonged exposure to high levels of noise. It results in permanent damage to the sensitive structures of the inner ear.


Noise Reduction (NR)

This is the reduction of unwanted noise levels in a space using acoustic treatments, barriers, or soundproofing techniques.


Noise Reduction Coefficient (NRC)

The Noise Reduction Coefficient (NRC) is a measurement of the sound-absorbing effectiveness of a material or surface. It ranges from 0 (no absorption) to 1 (total absorption).



A doubling or halving of a sound frequency.


Octave Band

An octave band is a range of frequencies where the upper limit of each band is twice the frequency of the lower limit. Octave bands are commonly used in acoustic measurements to assess sound across different frequency ranges.


1/3 Octave Band

Like an octave band, a 1/3 octave band divides the frequency range into smaller segments, where the upper limit of each band is approximately 1.26 times the frequency of the lower limit.



A doubling or halving of a sound frequency.



Excessive absorption of sound energy, leading to a deadened, overly dull acoustic environment.



PET is a type of plastic that is used to make things like water bottles, food containers, and even clothing. It’s strong, lightweight, and can be easily shaped into different forms, especially panels that help absorb sound.


Phase Cancellation

When two sound waves of the same frequency and amplitude interfere, resulting in reduced or canceled-out sound.


Porous Absorber

Acoustic material designed to absorb sound energy through friction and air movement within its structure.


Quiet Zone

An area designed to minimize or eliminate unwanted noise, often used in architectural design for specific purposes.


Reflection time

Reflection time, also known as reverberation time, is the time it takes for sound energy to decrease in intensity by 60 decibels after the sound source has stopped emitting sound. It indicates the persistence of sound in a space.



Reflections are sound waves that bounce off surfaces and objects in a room. They add to the overall sound quality of a space and affect its acoustic characteristics.



Reverberation is the continuation of sound in a space due to multiple reflections. It contributes to the overall acoustic character of a room and affects factors like clarity and perceived spaciousness.


Reverberation Time (RT60)

Reverberation time (RT60) is the time it takes for sound energy to decrease in intensity by 60 decibels after the sound source has stopped emitting sound. It’s a measurement of the reverberant characteristics of a space.



Rockwool, also known as mineral wool, is a type of insulation material made from natural or synthetic minerals, primarily basalt or slag. It is used in acoustic treatment due to its sound-absorbing properties.


Room Mode

Resonances caused by the interaction of sound waves in a room due to its dimensions and shape.



The sabin is a unit of sound absorption used to quantify the sound-absorbing characteristics of a surface or material. One sabin is equivalent to one square foot of surface area that absorbs sound perfectly.



The redirection of sound waves in various directions, often achieved through specialized surfaces or structures.



A specific form of sound, in acoustics it refers to the audio content being produced or transmitted.


Signal to Noise Ratio (SNR)

The signal-to-noise ratio (SNR) measures the ratio of the signal’s strength to the level of background noise. A higher SNR indicates better signal clarity.


Sound Absorber

A sound absorber is a material designed to absorb sound energy rather than reflect it. It helps reduce echoes and control the overall acoustic environment.


Sound Dampening

This is the reduction of sound reflections and reverberation in a space. This is achieved by using materials or treatments that absorb sound energy.


Sound Isolation

This involves using barriers and acoustic treatments to prevent sound traveling between different areas or spaces. The goal is to minimize unwanted sound transfer.


Sound Pressure Level (SPL or L)

This is a measure of the intensity or strength of a sound wave. It is expressed in decibels (dB) and indicates how loud a sound is.


Sound Reinforcement

This involves the use of audio equipment and technology to amplify and distribute sound to a live audience, ensuring that the sound is clear and evenly distributed.


Sound Transmission Class (STC)

This is a rating system used to measure the sound insulation properties of building materials, such as walls, doors, and windows. A higher STC indicates better sound isolation.


Sound waves

These are vibrations that travel through the air and carry sound energy from a source to a receiver. They can be characterized by their frequency, amplitude, and wavelength.



Spectrum refers to the distribution of energy across different frequencies in a sound. Spectra provide a visual representation of how the energy of a sound is distributed over the frequency range.


Speech Intelligibility

This is the ability to understand and comprehend spoken words. Good acoustic conditions and clear sound reproduction are essential for maintaining high speech intelligibility.


Speech Transmission Index (STI)

This is a measurement that quantifies the intelligibility of speech in different acoustic conditions. It considers factors such as background noise and reverberation.


Speed of Sound

This is the rate at which sound waves travel through a medium. In dry air at room temperature, the speed of sound is approximately 343 meters per second (about 1,125 feet per second).


Standing waves

Standing waves are patterns of sound wave interference that result in stationary regions of high and low pressure. They can occur in enclosed spaces and contribute to uneven sound distribution.



A speaker designed to reproduce low-frequency sound.


Threshold of Hearing

The lowest level of sound that can be heard by the human ear.


Threshold Shift

This is the change in an individual’s hearing threshold, indicating a temporary or permanent change in their ability to hear certain frequencies. It is often associated with exposure to loud noise.


Time Weighted Average

A measurement of an individual’s noise exposure over a specific period, typically an 8-hour workday. It considers varying noise levels and their durations.


Transmission Loss (TL)

This is the reduction in sound energy when sound waves pass through a barrier or partition. It measures the effectiveness of a material or structure in blocking sound transmission.



In acoustics, this refers to the use of materials, techniques, and modifications to control sound reflections, absorption, and overall acoustic characteristics in a space.



Sound frequencies above the human hearing range.


Vibration Isolation

Techniques used to prevent the transfer of vibrations from one structure to another.



This is the distance between two consecutive points of a sound wave that are in phase, such as two crests or two troughs. It is inversely proportional to frequency and affects the pitch of sound.



The shape and form of a sound wave, determining its characteristics.


White Noise

A random signal with equal intensity at different frequencies, used to mask other sounds.


XLR Connector

A type of electrical connector commonly used in audio equipment for balanced connections.


Yield Point

The threshold at which an acoustic material starts to permanently deform under stress.


Zero-Reflection Room

A space designed to eliminate sound reflections completely.


As we wrap up our journey through the Acoustics Glossary, you’re now armed with the vocabulary to turn any space into a sonic haven.  

Whether you’re revamping a recording studio, creating a cosy home vibe, curating the perfect ambience for a restaurant, fostering productive office spaces, or designing an auditorium, your newfound acoustics knowledge is your secret weapon. 

Think of it as your toolkit to sculpt acoustic environments that resonate with your vision. So, go ahead and play with acoustic treatments—turn your curiosity into creativity!