Technology: Audio vocab 101
Technology: Audio vocab 101
Becky Abel explores some of the most common keywords in the world of audio
Ensuring that your audio is at a high standard during worship events is an important role to take. The audio world is always changing, with new products and equipment making it hard to understand or keep up with the ever-evolving terminology. This can be confusing, especially if you’re new to the field, so here are some common keywords that will often come up.
Active/passive: an active device requires power to operate, as opposed to a passive device that doesn’t need power. Examples include ‘active crossovers’ and ‘active monitors’. Active speakers are those with an integrated amplifier, while passive speakers must be powered by an external amplifier.
Amplifier: a device that increases a signal’s power, voltage or current.
Balanced/unbalanced signals: when conductors are used to carry an audio signal, with a balanced signal, three conductors are used. Two of these conductors carry a positive and negative signal, while the third is used for grounding. With an unbalanced signal, only two conductors are used – one carries the positive signal while the other carries the negative and is used for grounding. XLR cables can be used to transmit balanced signals. While unbalanced signals are less complicated, they are more vulnerable to noise problems.
Biamp: a technique that involves feeding a loudspeaker with two separate amplifier channels, one for low frequencies (woofer) and a second for middle and high frequencies (tweeter). In order to biamp a system, the power from the amplifiers must be balanced and the speakers need to be within their frequency and power limits.
Bit depth: also referred to as a word length or bitrate. Used in digital audio, the bitrate is the dynamic range that is taken during recording. The higher the sound’s dynamic range, the higher the bitrate.
Bridged mono: used in audio amplifiers, this is a method in which a two-channel amplifier is bridged into one load, creating twice as much power.
Bus: where many signals in a point of a circuit are connected. With mixers, a bus carries signals from several inputs, mixes them together then transports them to an output. The higher the amount of busses that a mixer has, the more flexible its routing and controlling capabilities will be.
Cardioid: a heart-shaped polar pattern that rejects any sound that comes from the rear.
Compander: improves the signal-to-noise ratio by compressing a signal before it is recorded onto a tape.
Compressor: a signal processor that reduces or ‘evens out’ the dynamic range of an audio signal.
Condenser microphone: a type of microphone that uses a capacitor as a pickup. These are usually from an external source such as a mixing console. They are more sensitive than dynamic mics and are typically used in low-volume applications such as recording studios where background noise isn’t present.
Crossover: a device that creates two or three output signals from a single input signal. There are two types of crossovers: active and passive. An active crossover needs both power and ground connections; on the other hand, passive crossovers don’t require power to filter the signal.
Dante: short for Digital Audio Network Through Ethernet, Dante is a mixture of software, hardware and network protocols that distributes uncompressed, multichannel digital media through standard Ethernet networks.
Damping: an effect that decreases the amplitude of vibrations.
DAW: the abbreviation of Digital Audio Workstation. A DAW is software programme specially designed to record, edit and playback audio from a computer.
Decibel: measures signal volume levels using a logarithmic scale. Abbreviated to dB.
DSP: Short for digital signal processing. DSP is a form of manipulation on a digital audio signal, performing the same functions as an analogue signal processor.
Dynamic microphone: another type of microphone where the sound waves induce a current by causing a moveable wire or coil to generate electrical signals. This does not require external power. They are less sensitive than condenser mics and can handle high SPLs, making them more suited to loud sounds and high SPL environments such as live concerts.
EIN: short for equivalent input noise. This is the overall rating of noise performance from an amplifier that measures its quietness.
EMI: stands for electro-magnetic interference, which occurs where an electronic device is used in range of an electromagnetic field. This is also known as radio frequency interference.
Equalisation: abbreviated to EQ, equalisation is the process of adjusting various audio frequencies to correct or enhance the sound. Common types of EQ include parametric and graphic.
Envelope: defines how a sound will vary over time in terms of four attributes: attack, decay, sustain and release.
Frequency response: a way to measure the frequency range from an audio system that can handle, transmit or receive.
Filter: a frequency-dependent amplifier circuit that is designed to amplify, pass or attenuate ranges of frequency. Common filter types include high-pass, low-pass and bandpass filters. High-pass filters (also known as low-cut filters) attenuate the output of a signal below a specific frequency. Any frequencies higher than the cut-off point are passed through. A low-pass filter or high-cut filter performs the opposite action, while a bandpass filter can pass frequencies between its two cut-off frequencies while attenuating frequencies outside that range.
Gain: the amplification level of an audio signal which is usually expressed in decibels. It can be stated either as an input to an output voltage, a current or power.
Headroom: the difference between the maximum level of the signal being carried and the maximum level the device is capable of before distortion. By having more headroom, quick bursts of loud sounds will be reproduced cleanly and clearly. Headroom can be thought of as a safety zone, allowing transient audio peaks to exceed the nominal level without clipping.
Hertz: a unit of sound frequency that is abbreviated to Hz.
Impedance: resistance in an electrical circuit that is measured in Ω.
Limiter: a type of compressor designed to limit the level of a signal to a certain threshold. While a compressor will begin to smoothly reduce the gain above the threshold, a limiter will almost completely prevent any additional gain above the threshold. A limiter is a compressor with a very high compression ratio.
Line array: a combination of identical loudspeakers that are mounted together in the shape of a vertical line and fed in phase to create a line source output.
Mixing console: used to edit or mix multiple audio signals. Also used to change the volume, frequency content, stereo position, dynamics and effects of these signals. This is also known as a soundboard, mixing board, mixing desk and audio mixer.
Omnidirectional: a microphone that can equally pick up sound from any direction.
Peak: the highest level of strength of an audio signal or the level at which the signal begins to distort.
Phantom power: a +48V DC current sent through audio cables to provide power for devices such as condenser microphones.
Phase: if two or more waveforms are involved in producing a sound, their relative amplitudes can often be different at any one point in time. The relationship between the two signals is known as the phase. If two identical signals are played back 180° out of phase, they will completely cancel each other out.
Plosive: when an air blast goes into the microphone, producing a distorted sound. Typically occurs when a vocalist or presenter uses words that include a ‘per’ sound.
Point source loudspeaker: as the name suggest, this is a single speaker, or multiple speakers placed far apart, broadcasting a full range of sound from a single point.
Processor/effect: a processor is a piece of hardware or software that completely alters the pitch, speed, loudness or tone of a sound, while an effect inserts its own signal to the existing one. These are used in either live or recording situations.
Resonance: when physical substances vibrate at certain frequencies with more energy, for example, certain features of a room may resonate when music is played at a high volume.
Reverberation: the audible effect of the early reflection of sound waves bouncing off walls and other objects.
Quantisation: used in analogue-to-digital conversion, mathematical quantisation changes an analogue signal to a smaller set of steps in a digital quantity.
Sensitivity: the amount of a signal needed from an input in order to create a standard level of output. Both loudspeakers and microphones process sensitivity specifications.
Sibilance: the energy of the vocal sounds of ‘s’ and ‘sh’ that can sometimes cause recording problems. To fix this issue, a de-esser is used without disrupting too much of the vocal recording.
Sound pressure level: the measurement of volume or how loud a sound is, measured in dB. Abbreviated to SPL.
Stereo: a system of recording or reproducing sound that uses two channels, each playing a portion of the original sound in such a way as to create the illusion of locating the sound at a particular position in space.
Subwoofer and woofer: loudspeakers that replicate very low bass frequencies. Typically, woofers are designed to output frequencies between 200Hz to 5kHz, while subwoofers output frequencies below 200Hz.
Timbre: a wave pattern that occurs when overtones are present with the fundamental frequency. A violin playing the same note as a trumpet sounds different because each possesses a different timbre.
Transducer: a device that converts electrical input energy into mechanic output energy or vice versa. Examples of this include a microphone or a loudspeaker.
Tweeter: a transducer created to solely deliver high-frequency sounds.
WAV: stands for Waveform Audio. Created by Microsoft, this is a standard PC audio file format that is used for high-quality digital audio storage.
Wavelength: the distance between two crests or troughs of a waveform. The crest is the highest point of the wave and the trough is the lowest. The closer the crests and troughs are to one another, the shorter the wavelength and the higher the pitch of the sound. The further apart they are, the longer the wavelength and the lower the sound’s tone.
XLR: an electrical connector that is associated with balanced audio interconnection. This is used in professional AV and stage lighting equipment.
There is so much going on in this field; however, with the help of this glossary, you can become a bit more familiar with the world of audio.
This article was first published in the November-December 2019 edition of Worship AVL. Subscribe at www.proavl-central.com/subscribe/worship