Audio and Sound Design Glossary

Ambience

The background sound that establishes the atmosphere of a location. Can include traffic, wind, birds, people talking, air conditioning, or distant machinery. It helps make a scene feel as though it exists in a particular environment. For example, a scene in a busy city might contain car horns, footsteps, and distant conversations even when the characters are not speaking.

Amplitude

The size or strength of a sound wave, which relates to how loud a sound is perceived to be. Greater __ generally produces a louder sound, while smaller __ produces a quieter sound. A character whispering has a relatively small __ compared with a character shouting. __ is not the same as frequency, which relates to pitch.

Attenuate

To reduce the strength, level, or intensity of a signal. In sound production, __ often means lowering a sound's volume or reducing a signal as it travels through a medium. A sound editor might __ background music so dialogue is easier to understand. In lighting, __ can also refer to reducing light intensity, such as with a neutral-density filter.

Balanced audio

Audio in which the electrical signal is transmitted in a way that helps reject unwanted interference, usually through a balanced connection with two signal conductors and a shield. In practical recording, a balanced XLR cable helps preserve a clean microphone signal, particularly over long cable runs. The term can also describe a mix in which dialogue, music, and effects have appropriate relative levels, so context matters.

Bidirectional

A microphone pickup pattern that is most sensitive to sound coming from the front and rear, while rejecting much of the sound arriving from the sides. It is often called a figure-eight pattern. This can be useful when recording two people facing each other across a microphone, such as an interview, although room noise from the front and rear can also be captured.

Binaural hearing

The ability to hear with both ears and use the differences in sound arrival time and loudness between the ears to determine where a sound is coming from. __ helps us perceive the direction and location of sound in three-dimensional space. Filmmakers and sound designers can use spatial audio techniques to create a similar sense of immersion, such as making footsteps seem to approach from behind the listener.

Frequency

The number of complete cycles of a sound wave that occur each second. __ is measured in hertz (Hz) and is closely associated with perceived pitch: higher __ generally sound higher, while lower __ generally sound lower. A bass drum produces substantial low-__ energy, while a whistle produces higher-__ energy.

Harmonics

Frequencies that occur at whole-number multiples of a fundamental frequency. When a musical instrument or voice produces a note, the sound often contains the fundamental frequency plus harmonics. The relative strength of these components helps determine the sound's timbre. This is why a piano and a trumpet can play the same note but sound different.

Hertz (Hz)

The unit used to measure frequency, meaning cycles per second. A sound at 100 Hz completes 100 cycles each second; a sound at 1,000 Hz completes 1,000. In audio work, hertz is used to describe sound frequencies and sampling rates are commonly expressed in kilohertz (kHz). A higher number of hertz does not automatically mean a louder sound.

Pitch

The perceptual quality that allows us to describe a sound as high or low. __ is strongly related to the sound's fundamental frequency. A high-pitched alarm can create urgency or anxiety, while a low-pitched rumble can suggest weight, danger, or tension. __ is different from volume: a sound can be high-pitched and quiet or low-pitched and loud.

Sound timbre

The quality or character that makes one sound distinguishable from another even when both have the same pitch and approximate loudness. __ is shaped by harmonics, the sound's envelope, and other acoustic characteristics. A person's voice, a violin, and a synthesizer may all play the same note, but their different _ allow listeners to identify them.

Sound envelope

The way a sound's amplitude changes over time. A common model describes four stages: attack (how quickly the sound begins), decay (the initial drop after the attack), sustain (the continuing level), and release (how the sound fades after it ends or is released). A drum hit has a sharp attack and quick decay, while a sustained violin note may develop more gradually.

Wavelength

The physical distance between corresponding points on successive waves, such as one peak and the next. For sound traveling through the same medium, higher-frequency waves have shorter wavelengths, while lower-frequency waves have longer wavelengths. __ is related to frequency and wave speed, rather than being another name for pitch or loudness.

Waves

Repeating changes in pressure that travel through a medium, such as air, and carry sound energy. __ can be described by their amplitude, frequency, wavelength, and shape. A microphone converts sound pressure variations into an electrical signal, allowing the sound to be recorded, processed, and reproduced.

Crest

The highest point of a wave in a waveform representation. The __ represents a maximum positive displacement relative to the wave's reference level. In a simple wave, its height is part of the wave's amplitude.

Trough

The lowest point of a wave in a waveform representation. It is the point of greatest negative displacement relative to the reference level. The crest and trough together help describe a wave's amplitude, although digital audio meters typically show signal level rather than requiring you to identify individual wave cycles.

Capacitor microphones

Microphones that detect sound using a capacitor whose electrical properties change as a thin diaphragm vibrates in response to sound pressure. This design is commonly associated with condenser microphones. __ microphones can capture detailed sound and are widely used for dialogue, vocals, and studio recording. Many require power to operate their electronics.

Condenser microphone

A microphone that uses a diaphragm and backplate to form a capacitor. Sound moves the diaphragm, changing capacitance and creating an electrical signal. _ microphones are often sensitive and detailed, making them useful for studio dialogue, voice-over, and environmental recording. Many professional models use phantom power, although some designs use batteries or other power arrangements.

Electret

A material that retains a permanent electrical polarization, allowing it to provide the fixed charge needed in many condenser microphone designs. __ microphones are common in compact microphones, lavalier microphones, and consumer devices. The __ material reduces the need for an external polarization voltage, but the microphone's electronics may still require power.

Ribbon microphone

A microphone that uses a thin conductive ribbon suspended in a magnetic field. Sound makes the ribbon vibrate, generating an electrical signal. Traditional __ microphones often have a bidirectional pickup pattern and are known for a smooth, natural sound. They can be more delicate than some other microphone types, so handling and compatibility with power supplies matter.

Dynamic microphone

A microphone that commonly uses a moving coil attached to a diaphragm within a magnetic field. Sound causes the diaphragm and coil to move, producing an electrical signal. __ are often rugged and can handle loud sound sources, making them useful for interviews, performances, and location recording. Many do not need phantom power.

Handheld microphone

A microphone designed to be held in the hand, often by an interviewer, reporter, or performer. It can be dynamic or condenser and can have different pickup patterns. Its placement can be adjusted quickly, but changes in distance, hand movement, and handling noise may affect the recording.

Lavalier (lavaliere) microphone

A small microphone clipped to clothing, usually near the speaker's chest or collar. It allows dialogue to be recorded while leaving the speaker's hands free and keeping the microphone relatively unobtrusive. It is common in interviews and film production. Clothing rustle, jewelry, and distance from the mouth can affect the recording, so placement is important.

Shotgun microphone

A highly directional microphone, often designed with an interference tube to increase directionality at many frequencies. It is frequently mounted on a boom and aimed toward an actor from just outside the frame. It helps emphasize sound from the direction it is pointed, but it does not magically eliminate all surrounding noise, especially in reflective environments.

Cardioid microphone

A microphone with a heart-shaped pickup pattern when viewed from above. It is most sensitive at the front and less sensitive at the rear. It is useful for isolating a speaker from some background noise, provided the microphone is aimed correctly. Sound arriving from the sides or reflecting off nearby surfaces may still be captured.

Omnidirectional microphone

A microphone that picks up sound from all directions relatively evenly. It is useful for capturing natural ambience, group conversations, or a speaker whose position may change. It is less selective about the direction of sound, so it may record more surrounding noise than a directional microphone.

Unidirectional microphone

A microphone designed to be more sensitive to sound arriving from one direction than from others. Cardioid and shotgun microphones are common examples of __ designs. In filmmaking, a _ microphone is often aimed toward an actor to emphasize dialogue and reduce unwanted sounds from other directions.

Pickup pattern

The way a microphone's sensitivity varies according to the direction from which sound arrives. Common patterns include omnidirectional, cardioid, and bidirectional. The __ __ helps determine where to place the microphone and which sounds it will emphasize or reduce. A __ __ is not the same as frequency response, which describes sensitivity across different frequencies.

On-axis

A sound source positioned along the main direction of a directional microphone's intended pickup. A microphone generally captures sound most strongly and consistently when the source is … although the exact response depends on the microphone. Turning a microphone away from the speaker may change the sound's level and tonal quality.

Where should the microphone be directed?

For clear dialogue, aim the microphone's most sensitive area toward the speaker's mouth, while keeping it as close as practical without entering the frame. A boom operator may place it just above or below the frame. The best position depends on the microphone's pickup pattern, the actor's movement, and the room. Avoid pointing a directional microphone toward a loud unwanted source.

Phantom power

A method of supplying electrical power through a balanced microphone cable, commonly using 48 volts, to operate condenser microphone electronics. It is usually provided by a mixer, recorder, or audio interface. Many condenser microphones need it, while most dynamic microphones do not. Whether __ power is appropriate depends on the specific microphone and equipment.

Transducer

A device that converts one form of energy into another. A microphone is a transducer because it converts acoustic energy into an electrical signal. A loudspeaker is also a transducer because it converts an electrical signal back into sound. Transducers are essential to recording and playback systems.

Transduction

The process of converting energy from one form into another. In sound recording, a microphone performs acoustic-to-electrical transduction. During playback, a loudspeaker performs electrical-to-acoustic __. This conversion allows sound to be captured, stored, manipulated, transmitted, and reproduced.

Impedance

The opposition a circuit presents to alternating electrical current, measured in ohms. In audio, the impedance of a microphone, cable, input, or output can affect how equipment interacts. Microphone inputs are typically designed to accept the output impedance of the microphone. __ matching and proper connections help maintain reliable signal transfer.

Voltage

The electrical potential difference that helps drive current through a circuit. In an audio signal, __ changes represent variations in the recorded signal. Microphones produce relatively small __, which may need preamplification before recording. Phantom power is a separate DC supply delivered through a cable to power compatible equipment.

XLR

A type of connector commonly used for professional microphones and balanced audio connections. __ cables are robust and commonly have three pins for a balanced mono audio signal. They are widely used on film sets because they provide secure connections and help reduce interference over long cable runs when used in a balanced system.

Analog sound

In a recording context, __ audio represents changes in sound as a continuously varying electrical signal. It is not divided into discrete digital samples. Traditional tape records a physical representation of the signal, whereas digital recording measures the signal at intervals and stores numerical values. _ systems can still introduce noise and distortion.

Sampled sound

Digital audio created by measuring an analog signal at regular intervals. Each measurement is a sample, and the sequence of sample values represents how the sound changes over time. The sampling rate determines how many measurements are taken each second. For example, digital audio sampled at 48 kHz takes 48,000 samples per second.

Sampling rate

The number of samples taken per second when converting analog audio into digital audio. It is measured in hertz, commonly kilohertz. A higher __ __ can represent a wider frequency range, subject to the Nyquist limit and practical filtering. Common production rates include 44.1 kHz and 48 kHz, with 48 kHz widely used in film and video.

Bit depth

The number of bits used to represent each digital audio sample's amplitude. Greater __ allows more possible amplitude values and generally provides a wider theoretical dynamic range. For example, 16-bit and 24-bit recordings differ in the precision available for representing signal levels. __ is different from sampling rate: one concerns amplitude resolution, the other sampling frequency.

Quantized

Describes a signal whose measured amplitudes have been mapped to a finite set of numerical levels. During digital audio conversion, quantization assigns each sample to one of the available amplitude values. More bits provide more available levels. Quantization can introduce a small error, called quantization error, which is generally reduced by using greater bit depth and appropriate recording practices.

Flash memory

A type of nonvolatile electronic storage that retains data without continuous power. SD cards and many solid-state storage devices use __. In film production, __ can store recorded audio and video files, allowing crews to capture media digitally and transfer it for editing.

Compression

A process that reduces the size or dynamic range of information, depending on the context. Data compression makes files smaller for storage or transmission. Audio dynamic-range compression reduces the difference between louder and quieter portions of a signal. These are different uses of the same word, so identify whether a question concerns file size or sound dynamics.

Lossless compression

A method of reducing file size while preserving all of the original digital information, allowing the original data to be reconstructed exactly. Lossless audio formats are useful for archiving and editing because they avoid permanent information loss from the compression process. The resulting file is generally larger than a comparable lossy file.

Lossy compression

A method of reducing file size by permanently discarding some information, often based on assumptions about what listeners are less likely to notice. It is used in many streaming and distribution formats. __ __ can make files much smaller, but aggressive compression may introduce audible artifacts or reduce detail.

Frequency response

A description of how strongly a microphone or other audio device reproduces different frequencies. A flat frequency response reproduces frequencies relatively evenly across its specified range. Other microphones emphasize certain frequencies, potentially making voices sound brighter, warmer, or thinner. __ __ influences sound character but does not by itself determine overall recording quality.

Signal-to-noise ratio (SNR)

A comparison between the desired signal and unwanted background noise, commonly expressed in decibels. A higher __ means the wanted sound is stronger relative to the noise. On a film set, placing a microphone closer to an actor can improve the ratio by capturing more dialogue relative to distant room noise.

Decibel (dB)

A logarithmic unit used to express a ratio between quantities, including sound pressure levels and audio signal levels. In sound, __ help describe level differences because the range of audible sound is enormous. A change of 6 _ in the same voltage-based signal represents approximately a doubling or halving of voltage amplitude. _ must be interpreted according to the reference being used.

Dynamic range

The span between the quietest and loudest signals a system can represent or reproduce, or the difference between quiet and loud sounds in a recording. A film scene with a large __ may move from a whisper to a sudden explosion. Recording with sufficient headroom preserves loud peaks without clipping while keeping quieter sounds audible.

Sound presence

The sense that a voice or sound is immediate, clear, and close to the listener. __ can be affected by microphone distance, frequency balance, reverberation, and relative loudness. A close-miked voice with little room reflection may feel intimate, while a distant, reverberant voice may seem detached from the listener.

Sound perspective

The perceived distance and spatial relationship between a sound source and the listener. __ is created through relative loudness, frequency detail, reverberation, ambience, and stereo placement. A close voice often sounds clear and prominent, while a distant voice may sound quieter and more blended with the environment.

Stereo

An audio format using two channels, typically left and right, to create a sense of width and spatial position. By changing the relative level and timing of sounds between the channels, a mix can suggest that a source is to one side of the listener. __ is common in film and music, but it provides less fully directional placement than a properly configured surround system.

Surround sound

An audio system that uses multiple channels and speakers arranged around the audience to create a more immersive spatial experience. It can place sound sources in front of, beside, or behind the listener. In film, surround sound can make an audience feel surrounded by a crowd, a battlefield, a storm, or a moving vehicle.

Radio frequency (RF)

The range of electromagnetic frequencies used for wireless communication, including wireless microphones. An __ system transmits audio information from a transmitter to a receiver without a physical audio cable between them. Interference, obstacles, distance, and competing transmitters can disrupt the signal, so wireless systems require careful frequency coordination.

Broadcasting

Distributing audio or audiovisual content to an audience through a transmission system, such as radio, television, or digital platforms. Broadcast audio must meet technical requirements for signal level and quality. The term can also refer more broadly to the public distribution of a program or recording.

Streaming

Delivering audio or video over a network so that it can begin playing while data continues to arrive, rather than requiring the entire file to be downloaded first. __ platforms often use compression and adaptive bitrates to accommodate different network conditions. This makes media accessible quickly, though quality may vary with bandwidth.

Podcast

An episodic audio program, or an audio-centered program sometimes accompanied by video, distributed digitally for on-demand listening. __ commonly feature narration, interviews, conversations, music, and sound effects. Recording requires clear dialogue, consistent microphone technique, and control of background noise.

LED meter

A level meter that uses light-emitting diodes to display an audio signal's level. It helps a recordist monitor whether audio is too quiet, within the desired range, or approaching clipping. During production, an __ allows the sound recordist to adjust gain before a loud sound distorts.

VU meter

A meter designed to display an approximation of the average perceived level of an audio signal, with a relatively slow response to brief peaks. __ are useful for monitoring consistent loudness, particularly in speech and music. Because they do not respond quickly to every transient, a signal can peak too high even when the reading appears safe.

Peak

The highest level reached by an audio signal over a particular period. __ meters are useful for detecting sudden loud sounds that could overload a recording system. For example, a shout might have a brief _ much higher than the average level of the surrounding dialogue. Digital recording requires keeping peaks below the clipping limit.

Overmodulation

A condition in which a signal exceeds the level that a transmission or recording system can handle accurately. In radio transmission, excessive __ can cause distortion and interference; in digital audio, an overloaded signal may clip. A recordist prevents this by setting appropriate input gain and leaving headroom for unexpectedly loud sounds.

Ride the gain

To adjust recording input gain during a recording to keep the signal at a useful level as the sound source changes in loudness. For example, a sound recordist might lower the gain when an actor begins shouting. Gain adjustments must be made carefully to avoid abrupt level changes or added noise. In some situations, microphone placement and a fixed gain setting are preferable.

Monitoring

Listening to and checking audio while it is being recorded, edited, or played back. __ helps a filmmaker detect problems such as clipping, wind noise, interference, clothing rustle, or dialogue that is too quiet. Headphones are particularly important on set because a meter alone cannot reveal every audible problem.

Phase cancellation

A reduction in sound level that occurs when two versions of a signal combine with a timing or phase difference that causes them to partially or completely cancel one another. This can happen when two microphones record the same sound from different distances. The result may sound thin, hollow, or unusually quiet. Proper microphone placement and phase checks help prevent this problem.

Reverberation

The persistence of sound in a space after the original sound source stops, caused by many reflections arriving close together. A large hall often has longer __ than a small room with sound-absorbing materials. __ helps establish the acoustic character of a location, but too much can make dialogue difficult to understand.

Room tone

A recording of the quiet background sound present in a location, captured when no one is speaking and no deliberate action is taking place. __ might contain ventilation, distant traffic, or the subtle sound of the room itself. Editors use it to fill gaps between dialogue takes and prevent unnatural shifts into absolute silence.

Unbalanced audio

Audio carried by a connection that does not use the noise-rejection method of a balanced signal. Common connections include TS instrument cables and certain RCA connections. They can be suitable for short cable runs, but are generally more vulnerable to interference over longer distances connections.

Balanced vs. unbalanced audio

Balanced audio uses two signal conductors carrying opposite-polarity versions of the signal, plus a shield, so a compatible input can reject noise picked up along the cable. Unbalanced audio uses one signal conductor and a ground or return path. On a film set, a balanced XLR connection is generally preferred for professional microphones and longer cable runs.

Unidirectional velocity

Unidirectional means operating or pointing in one direction, while velocity describes the speed and direction of motion. In a microphone context, the likely related concept is a unidirectional pickup pattern, which emphasizes sound arriving from a particular direction.

High pitch / low pitch

High pitch refers to a sound perceived as relatively high, commonly associated with higher fundamental frequency. Low pitch refers to a sound perceived as relatively low, commonly associated with lower fundamental frequency. Filmmakers use pitch creatively: high-pitched sounds may suggest excitement, fear, or fragility, while low-pitched sounds can suggest heaviness, menace, or power. These are common associations, not universal rules.

Sampled sound vs. analog sound

Analog sound represents continuous changes in an electrical signal corresponding to the original sound. Sampled digital sound represents that signal through measurements taken at regular intervals and stored as numerical values. Digital sound can be copied without the generation loss associated with repeated analog copying, but its fidelity depends on sampling, bit depth, recording quality, and subsequent processing.

Projected sound

Sound that appears to come directly from a source and is perceived as being directed outward into the surrounding space. In a theatrical or cinematic context, __ sound can refer to a voice or other sound deliberately sent into the room or toward the audience.

Direct sound

Sound that travels from its source to the listener or microphone without first reflecting off a surface. __ generally provides clear information about the original source. In film production, a microphone close to an actor captures a greater proportion of dialogue relative to room reflections, often making the voice sound clearer and closer.

Reflected sound

Sound that reaches the listener after bouncing off surfaces such as walls, floors, ceilings, or furniture. __ sound can reveal the size, shape, and materials of a space. A voice in a tiled bathroom may have strong reflections, while a voice in a room with carpets and curtains may sound more controlled.

Reverberation (reverb)

The continuing sound created by many closely spaced reflections after the original source stops. __ can make a room feel large, hollow, intimate, or enclosed, depending on its character. Sound designers may preserve natural __, record in a different space, or add artificial __ to create a desired acoustic environment.

Echo

A distinct repetition of a sound caused by a reflection arriving late enough to be heard separately from the original sound. For example, a character shouting in a canyon might hear the word repeated. Unlike ordinary reverberation, where reflections blend into a continuous decay, an __ is perceived as a separate repeat.

Dolby 5.1

A surround-sound format using five main audio channels plus a low-frequency effects channel, commonly called the LFE channel. The five main channels are front left, center, front right, surround left, and surround right. The ".1" refers to the limited-bandwidth low-frequency effects channel, often reproduced through a subwoofer. In a film, dialogue can be anchored to the center channel while environmental effects surround the audience.

Placement of sound in a theater

The deliberate positioning of sound within a theater's speaker system to shape the audience's spatial experience. Dialogue may appear to come from the screen, while footsteps, music, or environmental effects can seem to come from the sides or behind the audience. Placement helps establish where an event occurs and guides attention. The effect depends on the theater's sound system and the film's mix.

Layers of sound

The different sound elements combined to form a film's soundtrack. These may include dialogue, narration, ambience, sound effects, music, and silence or near-silence. A filmmaker can layer distant traffic beneath dialogue and music to establish a city setting without showing every source. Layers also shape emotion, pace, realism, and audience attention.

Sound motif

A recurring sound, musical phrase, or sound pattern associated with a character, place, idea, or event. When the sound returns, it can remind the audience of an earlier moment or suggest that a particular theme is becoming important. For example, a recurring ticking sound might be associated with a character's anxiety about time. A sound motif is an audiovisual storytelling device, not merely any repeated noise.

Synchronous (sync) sound

Sound that corresponds in time to the action or image shown on screen. For example, when a character closes a door, the sound of the door closing occurs at the same moment. __ sound strengthens the apparent connection between what the audience sees and hears, making an event feel immediate and coherent.

Non-synchronous sound

Sound that does not occur at the same time as the visible action, or whose source is not directly matched to what is shown. A film might show a character walking while the sound of a later conversation plays over the image. This can create a connection between different moments, establish memory, or provide contrast between image and sound. Non-synchronous sound is not necessarily non-diegetic.

Diegetic sound

Sound that belongs to the world of the story and could, in principle, be heard by characters in that world. Examples include dialogue, a ringing phone, a radio playing in a room, and footsteps. __ sound helps create the sense that the story world exists beyond the camera's view.

Non-diegetic sound

Sound that is presented for the audience but does not originate within the story world as a sound the characters can hear. A dramatic orchestral score accompanying a chase is a common example. Non-diegetic sound can guide emotional interpretation, build suspense, or provide commentary on the action without requiring a visible or implied source inside the scene.

Narration

Spoken commentary that provides information, interpretation, or a perspective on the story. __ can be delivered by a character within the story, a character recalling past events, or an outsider. It may be diegetic or non-diegetic depending on its relationship to the story world. __ can clarify events, reveal subjective thoughts, or deliberately contradict the images.

Sound effect

A recorded, created, or manipulated sound used to represent an action, object, environment, or expressive idea. Examples include a door slam, thunder, footsteps, a futuristic machine, or an exaggerated heartbeat. Sound effects may be realistic, stylized, or symbolic. Their timing, volume, and texture can influence how the audience interprets an image.

Alvin Lucier

An experimental composer and sound artist known for exploring the physical behavior of sound and the relationship between sound, space, and perception. His work often demonstrates how acoustic environments transform what we hear. His piece I Am Sitting in a Room is particularly relevant to film and sound studies: a voice recording is played back into a room and rerecorded repeatedly, allowing the room's resonant frequencies to increasingly shape the sound.

Slate

A board or electronic device used to identify a take and synchronize picture and sound during production. A traditional clapperboard displays details such as the scene and take number and creates a sharp clap visible on camera and audible in the audio recording. Editors can align the visual closing of the sticks with the recorded clap to synchronize separate picture and sound recordings.

ADR (Automated Dialogue Replacement)

The process of rerecording dialogue in a controlled environment after the original scene has been filmed. An actor watches the scene and performs the dialogue again so that the new recording matches the timing, emotion, and mouth movements of the original performance. __ may be needed when location audio is noisy or a line must be changed. It requires careful editing and sound mixing to blend the replacement voice with the scene.