Dolby Atmos
An object-based surround sound format that adds a height dimension to channel-based mixes. A 5.1.2 system has five ear-level channels, one subwoofer channel and two height channels.
Also: Atmos, Dolby Atmos height channels Key terms
Glossary
Every definition is a self-contained, quotable paragraph with a permanent URL. Articles link here to ground their entities.
Height channels
Speakers or upward-firing drivers assigned to reproduce the vertical component of an object-based soundtrack. Dolby recommends a 30 to 55 degree elevation angle from the main listening position.
Also: Atmos modules, elevation speakersFrequency response
The measured output level of a speaker across the audible spectrum, normally stated in dB with a tolerance such as ±3 dB. A tighter tolerance over a stated range is more informative than the range alone.
Also: FR, bandwidthRoom modes
Standing-wave resonances determined by a room's dimensions. Axial modes below about 300 Hz are the main cause of uneven bass between seats, and are best treated with placement and multiple subwoofers.
Also: standing waves, axial modesBipolar speaker
A loudspeaker with driver arrays on opposing baffles radiating in phase, producing a wider, more diffuse sound field than a direct-radiating design. One of several available dispersion strategies, not a mark of quality.
Also: bipoleBass management
The processor rules that redirect low-frequency content from small channels to the subwoofer. An 80 Hz crossover is a starting point; the useful value depends on measured in-room response and subwoofer placement.
Also: crossover setting, small/large speaker settingCrossover frequency
The boundary where a signal is split between drivers or between a speaker and a subwoofer. In a passive loudspeaker it is fixed by the crossover network; in an AV processor it is a configurable setting verified by measurement.
Also: crossover point, XOSpeaker sensitivity
Sound pressure level produced at one metre from a 2.83 V input, stated in dB. It predicts how much amplifier voltage a speaker needs, but says nothing about impedance dips or how much current the amplifier must deliver.
Also: efficiency, dB/2.83V/1mSignal chain
The complete path from source to room: source, DAC or phono stage, preamplifier, power amplifier, loudspeakers and cables. A system is limited by its weakest stage and by the room, never by the most expensive box in the chain.
Also: system chain, reproduction chainLFE channel
The low-frequency effects channel, the '.1' in 5.1 or 7.1. It carries a dedicated effects track and is not the same as bass redirected from other channels by bass management.
Also: .1 channel, subwoofer channelStereo imaging
The perceived position and size of sounds between two loudspeakers. It depends on level and time differences at the listening seat, so symmetry and first reflections usually matter more than cable or amplifier branding.
Also: soundstage, phantom centre