Sound Glossary – Audio technical terms and technical words explained

Here is a list of sound terminology and definitions as complete as possible in 2008 including audio and surround sound formats in alphabetical order.

Audio Formats

AAC: (Advanced Audio Coding) Developed in part by Dolby Laboratories, the AAC is a digital audio encoding format similar to MP3, but offers a number of advantages to improve audio quality. These include higher-efficiency compression, more channels, and better handling of audio frequencies above 16 kHz. The AAC has been popularized by Apple with its music service called iTunes and the famous digital audio player iPod.

MP3: (MPEG-1 Audio Layer-3) Standard technology and format for compressing a sound sequence into a very small file by using a lossy compression algorithm. It’s also the most used sound format over the Internet because of its good compression ratio, up to 1:12. Common bit rates are: 128, 192, 256 and 320 Kbit/s.

WMA: (Windows Media Audio) Audio compression method developed by Microsoft. Previously known as MSAudio, this proprietary format was conceived as a competitor to the popular MP3 and RealAudio codecs. Especially effective at bit rates below 128 Kbit/s, it’s today one of the most popular codecs, together with MP3 and MPEG-4 AAC.

Surround Sound Formats

Dolby 3-D:  Dolby 3D uses a Dolby Digital Cinema projector that can show both 2D and 3D films. For 3D presentations, additional filters are used in the projector. One filter each for the Left Eye and Right Eye. Each filter allows different frequencies of Red, Green, and Blue light to pass through each of them. The filters are able to each produce a common color gamut but transmit light at different wavelengths. Glasses with complementary dichroic filters in the lenses are worn, which filter out either one or the other set of three light wavelengths. In this way, one projector can display the left and right stereoscopic images in an alternating cadence that is not visible to the guest.

Dolby Digital: (aka AC-3) Surround sound technology that delivers digital audio for up to 5.1 discrete channels (Left/Center/Right/Left surround/Right surround/Low-Frequency Effects) with full frequency response in all channels (3Hz — 20kHz).

Dolby Digital EX: (aka Dolby Digital Matrix 6.1) 6.1-channel surround sound format based on Dolby Digital including an additional rear center channel, matrixed into the rear channels.

Dolby Digital Live: Real-time encoding technology that brings surround sound to interactive audio, such as video gaming and PCs. This technology converts any multichannel audio signal to the Dolby Digital format and provides one-cable connectivity between a PC and home theater systems.

Dolby Digital Plus: (aka DD+ or E-AC-3) Surround sound format with eight full-range channels encoded up to 24-bit/96kHz per channel for a bit rate of 6.144 Mbit/s compared to 0.640 Mbit/s for Dolby Digital. This lossy audio compression scheme was developed specifically for HDTV and Blu-ray discs.

Dolby Headphone: Signal processing technology that delivers 5.1-channel surround sound over any stereo headphones.

Dolby Pro Logic: The foundation of the multichannel home theater experience. This technology is based on Dolby Surround and decodes audio sources encoded in two-channel such as videocassettes, DVDs and TV broadcasts, to four-channel playback (front left, front right with center and rear-mono matrixed channels).

Dolby Pro Logic II: Improved version of Dolby Pro Logic with a more intelligent matrix decoder which offers “bass management” as well as “width”, “dimension” and “panorama” controls. The Pro Logic II expands any two-channel source audio to a 5.1-channel full bandwidth playback (Left/Center/Right/Left surround/Right surround/Low-Frequency Effects).

Dolby Pro Logic IIx: Extension of Dolby Pro Logic II, this algorithm processes native stereo and 5.1-channel content to produce 6.1- or 7.1-channel playback with rear-mono.

Dolby True HD: Similar to DD+, the True HD was also developed for high-definition disc-based media. Including eight full-range channels (Left/Center/Right/Left surround/Right surround/Left back/Right back/Low-Frequency Effects), this lossless format delivers sound that is bit-for-bit identical to the studio master (24-bit/192kHz) through a single-cable digital connection for audio and video.

Dolby Virtual Speaker: Advanced signal processing technology that delivers 5.1-channel surround sound effects from just two speakers.

DTS Digital Surround: Surround sound technology similar to Dolby Digital that delivers digital audio for up to 5.1 discrete channels (Left/Center/Right/Left surround/Right surround/Low-Frequency Effects), but it can use higher bit-rate audio encoding which provides improved sound quality in theory.

DTS-ES Discrete 6.1: True 6.1-channel surround sound format where an additional surround back audio channel is discretely encoded into the DTS bit stream.

DTS-ES Matrix 6.1: Surround sound technology that delivers 5.1 discrete channels of standard DTS sound plus a sixth channel (matrixed into the left and right surround channels) of audio information to deliver 6.1-channel sound through one or two back surround speakers.

DTS Express: Previously known as DTS-HD Low Bit Rate, the DTS Express provides low bit rate audio coding for applications with 2- to 5.1-channel audio, focusing primarily on bandwidth constrained audio applications, such as Internet, broadcast audio, and secondary audio on next generation optical disc players. It’s currently used in picture-in-picture, director commentaries and other Blu-ray’s interactive features.

DTS-HD Master Audio: Previously known as DTS++ and DTS-HD, the DTS-HD MA supports up to eight discrete channels encoded in 24-bit/192kHz (Left/Center/Right/Left surround/Right surround/Left back/Right back/Low-Frequency Effects) and was developed especially for the new high-definition disc formats like Blu-ray and HD-DVD.

DTS-HD High Resolution Audio: Similar to the DTS-HD Master Audio, the HRA is encoded at 24-bit/96kHz per channel.

DTS Neo:6: Similar to Dolby Pro Logic II, the DTS neo:6 provides 6.1-channel matrixed surround sound from any stereo source.

DTS Surround Sensation: Down-converts DTS 5.1, 6.1, or 7.1 -channel soundtracks to stereo while processing a realistic simulation of surround sound for two-channel equipment such as headphones and 2.1-channel home theater systems.

THX Neural Surround: Technology that provides multi-channel surround sound (up to 7.1ch) encoded within a two-channel stereo format, developed especially for limited bandwidth such as digital audio,video games, video broadcasting and Internet streaming.

Audio Certifications

THX Select: (Thomlison Holman eXperiment) Created by Lucasfilm, the THX select is a certification for speakers as well as DVD/Blu-ray players which requires a 7.1 speaker configuration with two back-surround speakers engineered and designed to complement a THX Select2 certified A/V receiver. These must be designed to deliver optimal quality audio and video presentations in small to medium-sized residential rooms (overall room volume of circa 2,000 cu. ft.).

THX Select2: Certification for 7.1-channel A/V receivers designed for small to medium-sized residential rooms (overall room volume of circa 2,000 cu. ft.).

Others

Dolby Volume: Technology engineered to deliver consistent volume levels across channels and programs among sources and material.