Acoustic Sound Definitions

Absorption - The process of changing sound energy into heat energy with special materials. This will then lower the amount of sound reflected back.

Active - A type of PA speaker that is self powered; meaning that the speaker has a built in amplifier. Opposite to passive speakers.

Acoustical Environment - The features of a given room, influenced by the absorption, refraction and it's dimensions.

Acoustical Material - A fabric like material designed to absorb sound in reflective environments. (ex. gymnasium walls or church sanctuaries…etc.)

Acoustics - The science of sound and its properties/effects on a given environment.

Anechoic - Sound without any echo.

Amplifier - Audio amps (amplifiers) are the units that convert the finished, mixed signals (from the soundboard) into electrically, powerful signals for powering the loudspeakers.

Artificial reverberation - Sound passed through an acoustic or electric process in a common effect known as reverb. This method is used to make a sound/signal more realistic. Effect units may have default settings to simulate the sound in desired places or surfaces like; rooms, plates, concert halls, bathrooms, stadiums…etc.

Attack - The start/beginning of a sound. On a compressor unit, the attack refers to the speed in which the compressor begins to reduce the signal as it passes through the threshold. You will generally see an 'Attack' knob on compressor and gate units.

Attenuate - The reduction of an electrical or acoustical level.

Audible frequency range - Perceptible range of frequencies heard by the human ear. (20Hz to 20,000Hz)

Auditory system - The sensory system in the ear that gives the sense of hearing.

Background noise - Unnecessary noise from sources not pertaining to the object of significance. Structureborne, airborne and instrument noise are forms of unwanted noise. Background noise can be a cause of sound bleeding from other microphones. To help resolve this, the use of gates will be very helpful.

Bandpass filter - A filter that reduces signals under and above the desired passband.

Bandwidth - The entire frequency range of a system.

Bass - The lowest range of perceptible frequencies starting around 20 Hz.

Boomy - A listening term, that refers to an overload of lower end frequencies.

Bidirectional - Known as a type of pick-up pattern in microphones that will capture sound from the front and back of the diaphragm.

Bright - A listening term, that refers to an excess of higher end frequencies.

Channel balance - In a stereo system, the channel balance refers to the symmetry of sound levels between the left and right speakers. This action, on a sound board, is usually called 'panning'.

Clipping - A type of distortion that can occur when an amplifier is driven into overload. Clipping can happen throughout all the stages of your church PA system; starting from an input on a soundboard, to the final output of the amplifiers/speakers.

Cloud - An acoustical panel suspended from the ceiling to reduce the amount of reflections.

Compression - The process of reducing the dynamic range of a signal. Generally used for vocals, instruments and drums. How to set up compressors.

Crossover frequency - The dividing signal in a speaker of different frequencies

Decibel (dB) - A number represented for the loudness of sound to the human ear.

Digital Delay - Effect which controls the input of a signal and then repeats after a period of time. Delay units have controls for decaying of the echo and reverb.

DI Box - Direct Input Boxes are used to change different impedance levels from instruments to the soundboard.

Dynamic headroom - The ability of a sound device to reach musical peaks.

Echo - A sound that has returned from its original source and was delayed multiple times.

Equalization - The process of altering frequency responses of a device to achieve a desired response.

Equalizer - In a system, the equalizer is designed to change the frequency response of a signal.

Feedback - Unwanted interaction between the speakers and microphones of a PA system.

Frequency - The calculation of fast variations of a periodic signal, expressed in cycles per second (Hz).

Frequency Response - Changes in the sensitivity of a circuit or room with regards to frequencies.

Front of House - The area that the audience (or congregation) has access to. Mainly excluding the stage and behind stage. Normally where everyone sits or stands at a service or show.

Fundamental - The lowest frequency of a note.

Fusion Zone - When all sounds (natural, eclectically generated or reflected) are fused together and heard by an observer’s ears; this will result in the apparent increase in sound level. Also called, the Hass Effect.

Gain - An increase in level. On most soundboards, this is a function knob that enables the input level into a channel.

Hard room - An environment which the surfaces have a very low value of sound absorption and are reflective. Opposite from a soft room.

Headphones - A tool (device) for the ability to hear any specific instruments/channels.

Headroom - The capability of an amp to go past its rated power for short durations without distortion.

Hertz (Hz) - The unit of frequency that means the same as cycles per second. (Abbreviated as Hz)

Impedance - The resistance to the flow of electric energy measured in ohms.

KHz - Kilohertz - 1,000Hz.

Live end dead end - A treatment plan for acoustics that at one end of the environment it is reflective and the other end is very absorbent.

Loudspeaker - An electroacoustical transducer that alters electrical energy into acoustic (audible) energy.

Masking - Adding a presence of sound to one source by another.

Microphone - A device that converts sound waves (acoustical energy) into electrical signals.

Midrange - In a speaker, the midrange is created with a tweeter for high frequencies and a sub-woofer for the low end frequencies.

Monitor (Wedge) - A speaker or in-ear monitor system, used on a stage to send sound to the musicians.

Muting - A dramatic reduction in the volume level. On a soundboard this function is called the ‘mute’ button.

Noise - Interference of either an electrical or acoustical signal. Gates are ideal for greatly reducing acoustical noise on stage.

Octave - In interval multiples of two between the frequencies bands 20Hz-40Hz. Each octave you add on the lower end requires that your speakers move four times as much air.

Omnidirectional - Referred to as a type of pick-up pattern in microphones. Omni, meaning ‘all around’; captures sound from all directions (360°).

Patch Cable - Typically an unbalanced quarter inch (1/4) phone jack used to connect instruments and other devices. Not suggested to be used for powering monitors or speakers.

PA system - Public address system; its purpose to amplify any given source used for communication in public areas.

Passive - A type of PA speaker that is unpowered, so that the speaker needs an external amplifier source, like a powered mixer or a power amplifier, in order to operate. Opposite to active speakers.

Phantom Power (+48V) - A function on most soundboards used to send 48 votts of electrical currents through audio cables. Mostly all condenser microphones require phantom power to work.

Phon - Unit of the audible loudness level of a tone.

Pick-up Pattern - For every microphone there is a property know as directionality. Directionality is described as the microphone’s sensitivity to sound from numerous directions.

Pitch - The perspective frequency of tones.

Psychoacoustics - The science of sound and its interaction on the auditory system.

PowerCon - Used for connecting the amplifiers and speakers in a PA system. The end of the cable has a twist lock feature, to ensure the connectivity of the cable. Has a very similar design to the speakon cable.

PZM Microphone - A special type of condenser microphone that has a plate (flat surface) that vibrates to all sound locations near it. Also called a Pressure Zone or Boundary microphone.

Refraction - Sound that is redirected by a process of bending sound waves through material with different sound velocities.

Returns - A process used with effect units. A signal must be sent to an effect unit and then 'returned' back to the soundboard.

Reverberation - The persistence of sound when enclosed in a space, which has reflective properties, after the source of the sound, has stopped.

Reverberation time - The falling off of a sound in a closed environment because of reflections.

Slap back - A distinct reflection from a nearby surface.

Snakes - Audio snakes are used for carry many signals in a single cable, great for long distances.

Soft room - An environment with highly absorbent surfaces. Opposite from a hard room.

Sone - The unit of measurement used for the subjective loudness on the auditory system.

Sound insulation - The ability of a given environment’s, physical composition, to stop sound from leaving the wanted origin. Different types of insulation have numerous effects on the sound. This sound energy is not necessarily absorbed; however the sound maybe reflected back or the impedance may become mismatched.

Sound isolation - The degree of acoustical separation between two environments. Like a control room to the live recording room. Some headphones are also sound isolating.

(SPL) Sound pressure level - Expressed in decibels as the loudness or volume of a level.

Sound spectrograph - A device used to measure the level, frequency and time of a signal.

Sound waves - Frequency determines the length of waves and the amplitude (loudness) determines the height of the waves. 

Speakon cable - Used to connect amplifiers to speakers, generally used in pro audio systems. This connector has a twist lock feature, to ensure the connectivity of the cable. (Similar to the PowerCon connector)

Spectral balance - The balance across the whole frequency spectrum of the system.

Splaying - A physical attribute to an environment where the walls are purposefully constructed off square. This is done to imperfect the flow of returning sound waves. Another method used for reducing echoes.

Stereo - Artificial simulation of natural human hearing by creating a 3-D image through a system of supplying two different sources with slightly singular mixes and sounds. In the case pertaining to a PA system, this would be called the Left and Right channels. For true stereo to be achieved; the soundboard, processing amplifiers and two separate speakers must be available.

Subwoofer - A speaker cabinet created for low-frequency reproduction. The best ability that a subwoofer should reach is into the bottom octave (20-40Hz).

Tangential mode - A physical room atmospheric mode produced by reflections from four of the six surfaces.

Threshold of feeling - Sound pressure that can cause discomfort and pain. Situated around 120 dB above the threshold of hearing.

Threshold of hearing - The lowest sound level that can be heard by the auditory system. (around 20uPA)

Timbre - The superiority of a sound that can be notable from other sounds of similar pitch and level.

Tip-Ring-Sleeve (TRS) - Audio cable ends, generally used for connecting instruments through to the soundboard. Called TRS for its physical features. Tip is the left channel signal the Ring is the right channel signal and the Sleeve is normally the ground.

Tone - Is the result of an auditory sensation of the given pitch.

Treble - The highest of all frequencies in the audio spectrum.

Unidirectional - Referred to as the type of pick-up pattern in microphones that will only capture sound from one direction.

Watt - A unit of electricity and acoustical power. The energy is expressed in intervals of seconds.

White noise (ANS) - An audible noise with a constant frequency spectrum. This is used to calculate and equalize the response of a system.

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