| Absorption | The process of reducing the sound energy that is reflected from a surface by converting it into another form of energy, such as heat, through the use of sound-absorbing materials. |
| Acoustic | Relating to sound or the sense of hearing. |
| Acoustic analysis | The process of measuring and analyzing sound waves in order to understand their properties and characteristics. |
| Acoustic impedance | A measure of the resistance of a material to the passage of sound waves, which depends on the material’s density and elasticity. |
| Acoustic isolation | The process of preventing sound from traveling between two spaces by using materials that block or absorb sound waves. |
| Acoustic pressure | The force exerted by sound waves on a surface, typically measured in units of pascals (Pa). |
| Acoustic reflex | The involuntary contraction of muscles in the middle ear in response to loud sounds, which helps to protect the ear from damage. |
| Acoustic resonance | The phenomenon of amplification of sound waves that occurs when the frequency of an external sound wave matches the natural frequency of a resonant object, such as a guitar string or a tuning fork. |
| Acoustic treatment | The use of materials and techniques to modify the acoustic properties of a space in order to improve its sound quality or reduce unwanted noise. |
| Ambience | The overall quality or character of the sound environment in a space, including factors such as reverberation, reflection, and background noise. |
| Background noise | Unwanted sound that is present in a particular environment, such as traffic noise or the hum of machinery, which can interfere with communication or cause distraction. |
| Baffles | Large, flat objects used to reflect or absorb sound waves and to reduce echoes and reverberation in a room. |
| Bandwidth | The range of frequencies within which a particular device or system can operate or respond to. |
| Bass | The lower range of audible frequencies, typically between 20 and 250 Hz. |
| Bi-amping | The practice of using two separate amplifiers to power the low and high frequency drivers of a speaker system, in order to achieve greater accuracy and control over the sound output. |
| Binaural recording | A technique for capturing sound using two microphones that are placed at a distance similar to that between the human ears, in order to create a stereo image that closely resembles the original sound source. |
| Boundary effect | The phenomenon of increased sound pressure near boundaries, such as walls, ceilings, and floors, which can cause distortion and uneven sound distribution. |
| Box resonance | The phenomenon of a resonant frequency being produced by the air volume inside an enclosed space, such as a speaker cabinet or a musical instrument. |
| Brownian noise | A type of random noise that is caused by the random movement of particles, such as air molecules or electrons. |
| Burn-in | The process of subjecting an audio device, such as a speaker or amplifier, to a continuous period of use in order to stabilize its performance and reduce the effects of any initial manufacturing defects. |
| Cancellation | The phenomenon of two sound waves of equal amplitude and opposite phase meeting and canceling each other out, resulting in a decrease in overall sound level. |
| Ceiling attenuation | The reduction in sound transmission between adjacent floors in a building due to the absorption and reflection of sound waves by the ceiling structure. |
| Coherence | The degree to which two or more sound waves are in phase with each other, resulting in a more focused and clear sound. |
| Comb filtering | The interference pattern that results when two sound waves with similar frequencies and different arrival times combine, causing peaks and troughs in the frequency response. |
| Compression | The process of reducing the dynamic range of an audio signal by amplifying the lower-level signals and attenuating the higher-level signals. |
| Constant directivity | The characteristic of a loudspeaker or microphone that maintains a consistent sound pattern across a range of frequencies and angles. |
| Critical band | The frequency range over which the human ear is most sensitive to changes in sound level and frequency. |
| Critical distance | The distance at which the direct sound from a source is equal in level to the reverberant sound in a room, resulting in a loss of sound clarity and intelligibility. |
| Crossover | The circuit or electronic component used to divide an audio signal into separate frequency bands, which are then sent to different speakers or amplifiers. |
| Crosstalk | The phenomenon of sound leakage between channels in a stereo or multi-channel audio system, resulting in a loss of clarity and stereo separation. |
| Damping | The process of reducing the amplitude of sound waves by absorbing or dissipating their energy through the use of materials or devices. |
| Decibel (dB) | The unit of measurement used to express the relative loudness of a sound, with 0 dB corresponding to the threshold of human hearing and 120 dB corresponding to the threshold of pain. |
| Diaphragm | The thin, flexible membrane in a microphone or loudspeaker that vibrates in response to sound waves and converts them into electrical signals or air pressure waves. |
| Diffraction | The bending or spreading of sound waves as they pass through an opening or around an obstacle, which can result in interference patterns and changes in sound level. |
| Direct sound | The sound waves that travel directly from the sound source to the listener without any reflections or other interactions with the environment. |
| Directivity | The characteristic of a loudspeaker or microphone that determines the directionality of its sound output or reception. |
| Distortion | Any change or alteration of a sound wave that results in a departure from the original waveform, typically due to nonlinearities in the signal path or system components. |
| Doppler effect | The apparent change in frequency of a sound wave as the source or listener moves relative to each other, resulting in a perceived change in pitch. |
| Double bass | A large stringed musical instrument with a deep, resonant sound, typically used in classical, jazz, and popular music. |
| Duodecimo | A type of book format that is approximately 7 inches by 5 inches in size, typically used for small, portable books and publications. |
| Earmuffs | Protective headphones that cover the entire ear and provide noise reduction or attenuation for workers in noisy environments. |
| Echo | The reflection of sound waves off of a hard surface, resulting in a delayed and slightly distorted version of the original sound. |
| Echo chamber | A specially designed room or enclosure that is highly reflective and used to create artificial echoes and reverberation for music or other sound effects. |
| Echoic memory | The sensory memory system responsible for briefly retaining auditory information, such as an echo or other sound, for a few seconds after it has ended. |
| Elasticity | The property of a material that allows it to deform under stress and return to its original shape when the stress is removed. |
| Electric guitar | A type of guitar that uses electromagnetic pickups to convert string vibrations into electrical signals, which can then be amplified and processed to produce a variety of sounds. |
| Electroacoustics | The branch of acoustics that deals with the generation, transmission, and reception of sound using electrical or electronic devices, such as microphones, loudspeakers, and amplifiers. |
| Envelope | The overall shape and duration of a sound wave, which includes the attack, sustain, decay, and release phases. |
| Equalization (EQ) | The process of adjusting the frequency response of an audio signal using an equalizer, which can boost or cut certain frequency bands to enhance or remove specific elements of the sound. |
| Exciter | A type of audio processing device that enhances the high-frequency content of an audio signal, typically used to add brightness or presence to vocals, guitars, or other instruments. |
| Far field | The region of space far away from a sound source, where the sound waves are considered to be essentially planar and have a consistent directionality. |
| Feedback | The phenomenon of sound waves from a loudspeaker or other sound source being picked up by a microphone and re-amplified, resulting in a high-pitched squealing or ringing noise. |
| FFT (Fast Fourier Transform) | A mathematical algorithm used to analyze the frequency content of a time-varying signal, such as an audio waveform. |
| Filter | An electronic circuit or device that selectively attenuates or amplifies certain frequency bands of an audio signal. |
| Flat response | The characteristic of an audio system or device that has a uniform frequency response, meaning that it reproduces all frequencies with equal accuracy and without any significant emphasis or attenuation. |
| Flutter echo | A rapid succession of echoes caused by sound waves reflecting back and forth between two parallel surfaces, resulting in a distinct fluttering sound. |
| Fourier analysis | The process of decomposing a complex waveform into its individual frequency components using Fourier series or Fourier transforms. |
| Frequency | The number of complete cycles or vibrations per unit time of a sound wave, measured in Hertz (Hz). |
| Frequency response | The range of frequencies that an audio system or device can accurately reproduce, typically expressed as a graph of amplitude versus frequency. |
| Fundamental frequency | The lowest frequency component of a complex sound wave, which determines its perceived pitch. |
| Gain | The amount of amplification applied to an audio signal by an electronic device, such as a microphone preamp or guitar amplifier. |
| Gamelan | A traditional ensemble of Indonesian musical instruments, typically consisting of metallophones, drums, and gongs, and known for its intricate and melodic compositions. |
| Glottal stop | A speech sound made by briefly closing the vocal cords in the throat, creating a momentary pause or gap in the flow of air. |
| Gradient microphone | A type of directional microphone that uses sound wave phase differences to selectively capture sound from a specific direction. |
| Graphic equalizer | An equalizer that uses a series of sliders or graphic representations to adjust the amplitude of specific frequency bands in an audio signal. |
| Ground loop | A type of electrical interference that can occur in audio systems when multiple devices are connected to a common ground, resulting in hum or noise. |
| Guitar | A stringed musical instrument with a flat back, curved top, and long fretted neck, typically played by strumming or plucking the strings with the fingers or a pick. |
| Gustation | The sense of taste, which detects and interprets the flavors and textures of food and other substances. |
| Gyroscopic effect | The tendency of a rotating object, such as a spinning loudspeaker, to resist changes in its orientation or direction of motion. |
| Haas effect | The psychoacoustic phenomenon whereby a sound is perceived as being located in the direction of the first arrival of the sound, even if there are subsequent reflections or echoes. |
| Harmonic | A component of a complex sound wave that is an integer multiple of the fundamental frequency, and which contributes to the overall timbre or tone quality of the sound. |
| Headphone | A type of audio transducer that is worn over the ears and produces sound directly into the ear canal, typically used for personal listening or monitoring. |
| Helmholtz resonator | A type of acoustic resonator consisting of a small cavity connected to a narrow neck or aperture, which amplifies certain frequencies of sound due to the resonance of the air inside the cavity. |
| Hertz (Hz) | The unit of measurement for frequency, defined as one cycle per second. |
| High-pass filter | A type of filter that selectively allows high-frequency components of an audio signal to pass through while attenuating or blocking lower frequencies. |
| Horn | A type of acoustic transducer that uses a flaring or conical shape to amplify and direct sound waves, typically used in loudspeakers, musical instruments, or communication systems. |
| Humidity | The amount of water vapor present in the air, which can affect the speed of sound propagation and the resonance of acoustic spaces. |
| Hybrid sound reinforcement | A technique of combining live acoustic instruments or voices with electronic amplification and processing, typically used in concerts or other live performances. |
| Hypercardioid | A directional microphone pattern that has a more narrow and focused pickup angle than a cardioid microphone, typically used for isolating a specific sound source in a noisy environment. |
| Impedance | The measure of resistance that an electrical circuit or device presents to the flow of alternating current (AC), often used in relation to audio equipment such as speakers, amplifiers, and microphones. |
| Impulse response | The acoustic response of a space or system to a short, transient sound impulse, typically used to measure and analyze the frequency response, reverberation time, and other acoustic characteristics of a space. |
| Infrasound | Sound waves with frequencies below the lower limit of human hearing, typically less than 20 Hz, that can be felt as vibrations rather than heard as audible sound. |
| Intensity | The amount of sound energy per unit area that is transmitted through a medium, typically measured in decibels (dB) and used to describe the loudness or volume of sound. |
| Interference | The phenomenon of two or more sound waves interacting with each other, resulting in constructive or destructive interference patterns that can affect the overall sound quality. |
| Inverse square law | A physical law that describes the reduction in sound intensity that occurs as the distance from a sound source increases, with sound intensity decreasing by a factor of four for each doubling of distance. |
| Inversion | A type of acoustic phase interference that occurs when the phase relationship between two sound waves is reversed, resulting in cancellation or reinforcement of certain frequencies. |
| Isochronous | A term used to describe sound waves that have a constant or uniform period or frequency, resulting in a regular or rhythmic sound pattern. |
| Isolation | The process of preventing unwanted sound from entering or leaving a space, typically through the use of acoustic barriers or materials. |
| Jitter | In digital audio, jitter refers to the small variations in the timing of a digital audio signal, which can result in distortion or artifacts in the sound. Jitter can be caused by imperfections in the clocking system of a digital audio device, as well as by electrical or electromagnetic interference. Jitter can be minimized through the use of high-quality clocking systems, signal processing algorithms, and shielding techniques. |
| K-weighting | A type of frequency weighting used in sound level meters to simulate the frequency response of the human ear. K-weighting applies a correction factor to sound levels at different frequencies to account for the varying sensitivity of the human ear to different frequencies. K-weighting is often used in noise measurements to provide a more accurate representation of the perceived loudness of the sound. |
| Leakage | The amount of sound that escapes from a space or system, typically measured in decibels (dB) and used to evaluate the effectiveness of acoustic isolation. |
| Level | A measure of the intensity of sound, typically expressed in decibels (dB), which compares the sound pressure level to a reference level. |
| Line array | A type of loudspeaker system that uses multiple identical speaker elements arranged in a vertical line, which can provide greater control over the directivity and dispersion of sound. |
| Linear phase | A type of filter or equalizer that maintains a constant delay across all frequencies, which can help preserve the time coherence and transient response of audio signals. |
| Live sound | The production and reproduction of sound in real-time for live events, such as concerts, theater performances, and sporting events. |
| Longitudinal waves | A type of sound wave in which the particles of the medium vibrate parallel to the direction of wave propagation, which is the opposite of transverse waves. |
| Loudness | The subjective perception of sound intensity, which can vary based on the frequency, duration, and other characteristics of the sound. |
| Loudspeaker | An electromechanical device that converts electrical signals into sound waves, typically by vibrating a diaphragm or cone. |
| Low-pass filter | A type of filter that passes signals with frequencies below a certain cutoff frequency while attenuating signals with frequencies above the cutoff frequency. Low-pass filters are often used in audio processing to remove high-frequency noise or to limit the bandwidth of audio signals. |
| Magnetic field | A field of magnetic force that surrounds a current-carrying conductor or a permanent magnet, which can induce an electrical signal in a nearby conductor or magnetizable material, such as a microphone or loudspeaker. |
| Magnitude response | The amplitude or gain of an acoustic or electrical system as a function of frequency, typically represented by a frequency response curve. |
| Masking | The phenomenon by which a loud sound can make a quieter sound inaudible or less noticeable, typically due to the frequency overlap and temporal masking of the two sounds. |
| Max SPL | The maximum sound pressure level that a loudspeaker, microphone, or other acoustic device can produce or tolerate before reaching its distortion or damage limits. |
| Microphone | An acoustic transducer that converts sound waves into electrical signals, typically by using a diaphragm that vibrates in response to the sound pressure. |
| Mid-range | The frequency range in the middle of the audible spectrum, typically between 200 Hz and 5 kHz, which is important for speech intelligibility and musical balance. |
| Modal analysis | A technique for characterizing the resonant frequencies, modes, and damping properties of structures or spaces, typically using vibration or acoustic measurements. |
| Modal density | The number of resonant modes per unit frequency range in a given space or structure, which can affect the sound field and acoustic response of the space. |
| Music production | The process of creating and recording music using various techniques and tools, including digital audio workstations, mixing consoles, and signal processing. |
| Natural frequency | The frequency at which a system or structure will vibrate freely when excited or perturbed, typically determined by its physical properties and boundary conditions. |
| Near-field | The region of sound field in the immediate vicinity of a source or listener, where the sound pressure and other acoustic parameters may differ significantly from those in the far field. |
| Node | A point or region in a standing wave or vibration pattern where the displacement of the medium is zero or minimal, which can result in reduced sound pressure or cancellation. |
| Noise | Any unwanted sound, typically characterized by its random or non-periodic nature, that can interfere with communication, cause annoyance, or have adverse effects on health and well-being. |
| Noise cancelling | A technique for reducing unwanted noise by generating an anti-phase sound wave that cancels out the original sound wave, typically used in active noise control systems or noise-cancelling headphones. |
| Noise floor | The level of background noise or interference in a measurement or recording system, which can limit the dynamic range or sensitivity of the system. |
| Nonlinear distortion | Any type of distortion or alteration of a signal that is not linear or proportional to the input, typically caused by nonlinearities in a system or component, such as clipping, saturation, or intermodulation. |
| NRR | Abbreviation for Noise Reduction Rating, a measure of the effectiveness of hearing protectors in reducing the sound level that reaches the ears, typically expressed in decibels. |
| Nyquist frequency | The maximum frequency that can be sampled or represented accurately in a digital signal processing system, typically half of the sampling rate according to the Nyquist-Shannon sampling theorem. |
| Occlusion effect | The increase in perceived loudness or bass response that can occur when wearing earplugs or in-ear headphones that block the ear canal, resulting in a change in the acoustic impedance and resonance of the ear canal. |
| Octave | A musical interval or frequency ratio of 2:1, representing a doubling or halving of the frequency, which is commonly used in music theory, acoustics, and signal processing. |
| Octave band | A frequency band that spans one octave, typically defined by its center frequency and its upper and lower limits, which is commonly used in noise measurement, analysis, and control. |
| Omnidirectional | A term used to describe microphones or loudspeakers that have a uniform or equal response in all directions, typically used for capturing or reproducing ambient or diffuse sound fields. |
| Open-back | A type of headphone or loudspeaker design that allows sound waves to escape from the back of the driver or diaphragm, creating a more natural or spacious sound stage, but with less isolation and more leakage. |
| Organic design | A design approach that emphasizes natural or biological forms, materials, and processes, typically used in architectural acoustics, product design, and environmental design. |
| Outdoor acoustics | The study and practice of acoustics in open or outdoor environments, typically involving the propagation, reflection, and attenuation of sound waves in the atmosphere, as well as their interaction with surfaces and sources. |
| Overload | The condition in which an acoustic device, such as a microphone, amplifier, or speaker, is subjected to a signal or power level that exceeds its maximum capacity or rated performance, resulting in distortion, clipping, or damage. |
| Overtone | A higher frequency component of a complex sound or vibration pattern that is a multiple of the fundamental frequency, typically responsible for the timbre or tonal quality of the sound. |
| Phase | The relative timing or alignment of two or more sound waves or signals, typically measured in degrees or radians, which can affect their interference, reinforcement, or cancellation. |
| Phon | A unit of loudness or subjective loudness level, which is based on the equal-loudness contours of the human ear and is defined as the loudness of a 1 kHz tone at 40 dB sound pressure level. |
| Pink noise | A type of random noise that has equal energy per octave or per frequency band, resulting in a flat or constant spectral density, which is commonly used in acoustic testing and calibration. |
| Pitch | The perceptual attribute of a sound that corresponds to its frequency, typically measured in hertz, which determines its perceived musical or tonal quality. |
| Power amplifier | An electronic amplifier that amplifies the power or voltage of an audio signal to drive loudspeakers or other loads, typically used in sound reinforcement, recording, and playback systems. |
| Pressure | The physical quantity that represents the force per unit area exerted by sound waves or other phenomena on a surface or medium, typically measured in pascals. |
| Proximity effect | The increase in bass or low-frequency response that can occur when a directional microphone or loudspeaker is placed close to a sound source, resulting from the boundary effect and the reduction of the sound field dimension. |
| Psychoacoustics | The branch of acoustics that deals with the study of the perception and cognition of sound by humans and animals, including the psycho-physical, physiological, and cognitive aspects of auditory processing. |
| Q factor | A dimensionless parameter that describes the shape or bandwidth of a resonance or filter, defined as the center frequency divided by the bandwidth at the half-power or -3 dB points, which is a useful metric for designing and characterizing acoustic and electronic systems. |
| Quadratic residue diffuser | A type of diffuser that uses a series of wells or cavities of different depths and shapes to scatter sound waves in multiple directions while preserving their energy and coherence, which can improve the diffusion and spatial quality of sound fields in rooms and halls. |
| Reflection | The bouncing back of sound waves from a surface or boundary, resulting in changes of direction, amplitude, phase, and timbre of the sound field, which can affect the clarity, intelligibility, and spatial perception of sound. |
| Reflection coefficient | The ratio of the reflected sound pressure to the incident sound pressure at a surface or boundary, which depends on the acoustic impedance of the surface and the angle of incidence of the sound wave. |
| Resonance | The natural frequency or vibration mode of a mechanical or acoustic system, resulting from the balance between its stiffness and mass or its acoustic impedance and admittance, which can amplify or dampen specific frequencies or harmonics in sound. |
| Reverberation | The persistence or decay of sound in an enclosed or reflective space, resulting from multiple reflections and interactions between sound waves and surfaces, which can create a sense of spaciousness, envelopment, and sustain in music and speech. |
| Reverberation time (RT) | The time it takes for the sound pressure level to decay by 60 dB or one millionth of its original intensity after the sound source has stopped, which is a key parameter for characterizing and designing the acoustic properties of rooms and halls. |
| Room acoustics | The study and design of the acoustic properties and behavior of enclosed or semi-enclosed spaces, including the measurement, analysis, and control of sound transmission, absorption, reflection, diffusion, and reverberation, which can affect the intelligibility, quality, and comfort of speech, music, and noise. |
| Room modes | The resonant frequencies or standing waves that exist in a room or enclosed space, resulting from the reflections and interactions between sound waves and boundaries, which can affect the frequency response, decay time, and spatial distribution of sound. |
| Room-in-room construction | A building technique that uses double walls, floors, and ceilings with air gaps or insulation between them to reduce the transmission of sound and vibration between adjacent rooms or between inside and outside of a building, which is commonly used in recording studios, cinemas, and concert halls. |
| Sound | A physical phenomenon that involves the vibration of air molecules or other media, which creates a pressure wave that can be detected by the human ear or other sensors and perceived as auditory sensations of pitch, loudness, and timbre. |
| Sound absorption | The reduction of the sound pressure level caused by the conversion of sound energy into other forms of energy, such as heat, due to the interaction between sound waves and porous or fibrous materials with low acoustic impedance and high flow resistivity, which can improve the acoustic comfort, clarity, and speech intelligibility in rooms and buildings. |
| Sound barrier | A structure or material that blocks or reduces the transmission of sound energy between two spaces or environments, typically by having high mass or stiffness, which can mitigate the impact of noise pollution on human health and well-being. |
| Sound diffraction | The bending or spreading of sound waves around obstacles or edges, which can create shadow zones, interference patterns, and diffraction patterns in the sound field, and affect the spatial perception and intelligibility of sound. |
| Sound field | The distribution and properties of sound waves in a given space or volume, which can be characterized by the sound pressure level, frequency response, directionality, and coherence of the sound. |
| Sound insulation | The reduction of the sound transmission through a barrier or partition between two spaces, typically by using materials with high acoustic impedance or mass, or by increasing the distance between the sound source and the receiver, which can improve the privacy, comfort, and acoustics of buildings. |
| Sound power | The rate at which a sound source emits acoustic energy, measured in watts or decibels, which is a key parameter for predicting the sound pressure level and noise exposure in a given space or distance. |
| Sound pressure level (SPL) | The logarithmic measure of the sound pressure in a given space or distance, relative to a reference pressure of 20 micropascals, expressed in decibels, which is a common metric for characterizing and regulating the intensity and annoyance of noise. |
| Sound quality | The subjective impression of the tonal balance, clarity, richness, and naturalness of a sound or music, which can be influenced by various factors such as the frequency response, dynamic range, distortion, and spatial properties of the sound. |
| Sound reinforcement | The use of electronic or acoustic systems to amplify, process, and distribute sound signals in a given space or venue, such as public address systems, concert sound systems, and studio monitoring systems, which can enhance the audibility, intelligibility, and impact of music, speech, and other sounds. |
| T60 | The time required for a sound in a room to decay by 60 dB, commonly used to measure the reverberation time and the acoustic quality of concert halls, recording studios, and other performance spaces. |
| Threshold of hearing | The minimum sound pressure level that can be detected by the human ear at a given frequency, typically around 0 dB SPL at 1 kHz for normal hearing. |
| Threshold of pain | The sound pressure level that causes physical pain and discomfort in the human ear, typically around 120 dB SPL or higher. |
| Timbre | The characteristic quality of a sound that distinguishes it from other sounds of the same pitch and loudness, and is determined by the relative amplitudes of its harmonics and overtones. |
| Transfer function | The mathematical relationship between the input and output signals of a system or process, which can be used to analyze and design filters, amplifiers, and other signal processing devices. |
| Transient response | The ability of a system or device to respond quickly and accurately to sudden changes in the input signal, often characterized by the rise time, settling time, and overshoot of the output response. |
| Transmission loss | The reduction of sound energy when it passes through a barrier or partition, commonly expressed in decibels as the difference between the sound pressure level on one side of the barrier and the other side. |
| Traveling wave | A wave that propagates through a medium or structure without changing its shape or amplitude, typically associated with the behavior of sound waves in pipes, strings, and other resonant systems. |
| Tuning fork | A small metal instrument that produces a pure tone of known frequency when struck, often used as a reference standard for tuning musical instruments and testing hearing acuity. |
| Two-point discrimination threshold | The minimum distance between two points of contact on the skin that can be perceived as separate sensations, which is a measure of the spatial acuity of touch and related to the density of mechanoreceptors in the skin. |
| Ultrasonic cleaning | A cleaning process that uses ultrasound to generate high-frequency sound waves in a liquid or solvent, which creates cavitation bubbles that remove dirt and contaminants from surfaces. |
| Ultrasonic testing | A non-destructive testing technique that uses ultrasound to detect flaws or defects in materials, such as welds, pipes, or metal parts. |
| Ultrasound | Sound waves with frequencies higher than the upper limit of human hearing, typically above 20 kHz. |
| Underdamped | A system or device that exhibits a response with a slow decay rate after being disturbed, resulting in oscillations or ringing. |
| Uniform sound field | A sound field in which the sound pressure level is constant at every point in space, typically achieved by using a large number of sound sources distributed evenly around a room or space. |
| Unit of measurement | A standard quantity used to measure acoustic parameters, such as the decibel (dB) for sound pressure level, the hertz (Hz) for frequency, and the meter (m) for wavelength. |
| Unity gain | A condition where the output signal of an amplifier or signal processing device is equal in amplitude to the input signal, resulting in a gain of 1 or 0 dB. |
| Unoccupied space | An area that is not occupied by people, such as a storage room, closet, or mechanical room, and typically has lower acoustic requirements than occupied spaces. |
| Unwanted noise | Any sound that is considered unwanted or annoying, such as traffic noise, HVAC noise, or background noise in a recording. |
| Upper cutoff frequency | The highest frequency that can be transmitted by a filter or amplifier without significant attenuation, typically specified by the -3 dB point of the frequency response curve. |
| Velocity | The rate at which a sound wave travels through a medium, typically measured in meters per second (m/s). |
| Vent | An opening or channel in a loudspeaker enclosure or other acoustic device that allows air to move in or out, typically used to tune the bass response or reduce distortion. |
| Vibration | A rapid back-and-forth motion or oscillation of an object or structure, typically caused by a force or disturbance. |
| Vibrato | A musical effect produced by a slight and rapid variation in pitch, typically used in vocal or instrumental music to add expression or emotion. |
| Virtual acoustics | The simulation or modeling of acoustic environments using computer software, typically used in architectural acoustics and audio engineering. |
| Vocal range | The range of pitches that a singer or speaker can produce with their voice, typically measured in octaves or specific frequency ranges. |
| Vocoder | A device or software program that analyzes the spectral characteristics of a sound and applies them to a synthesizer or other sound source, typically used in electronic music and voice processing. |
| Voice coil | A coil of wire that is suspended in a magnetic field and used to convert electrical signals into mechanical vibrations in a loudspeaker or other transducer. |
| Void | A space or area within a structure or room that is not filled with sound-absorbing materials or other acoustical treatments, leading to echoes or excessive reverberation. |
| Volume | The perceived loudness or amplitude of a sound, typically measured in decibels (dB). |
| Waveform | A graphical representation of a sound wave that shows the amplitude, frequency, and phase of the wave over time. |
| Waveguide | A structure in a loudspeaker or other acoustic device that directs sound waves in a specific direction or pattern, typically using reflections and diffraction. |
| Wavelength | The distance between two consecutive points on a sound wave that are in phase, typically measured in meters or feet. |
| Whisper room | A soundproofed room designed for recording or other activities that require a high level of acoustic isolation and low background noise. |
| White noise | A random signal that contains equal power at all frequencies within a specified bandwidth, typically used for masking unwanted sounds or as a test signal in acoustical measurements. |
| Wind noise | The noise produced by wind blowing across a microphone or other acoustic device, typically reduced by using a windscreen or windjammer. |
| Wing | A structure in a concert hall or other large space that extends from the stage or platform and helps to distribute sound evenly throughout the audience area. |
| Wireless microphone | A microphone that transmits audio signals wirelessly to a receiver or other device, typically used for live performances or public speaking. |
| Woofer | A loudspeaker driver designed to reproduce low-frequency sounds, typically with a diameter of 8 inches or more. |
| Work environment noise | Noise that is present in a workplace and may affect workers’ health, safety, or performance, typically regulated by occupational health and safety standards. |
