Augmentative and alternative communication ( AAC ) is an umbrella term that encompasses methods of communication for those with impairments or restrictions on the production or comprehension of spoken or written language.

AAC is now used for a wide variety of speech impairments.

Clearly, an evaluation of a user's abilities and requirements is necessary to match a user with the most appropriate AAC method, input approach, and vocabulary.

The popular MP3 format is probably the best-known example, but the AAC format found on the iTunes Music Store is also common.

This is similar in many respects to how raw. AAC files are tagged ( but this is less supported nowadays, e. g. iTunes ).

Part 7 is referred to as MPEG-2 AAC.

AAC is more efficient than the previous MPEG audio standards, and is in some ways less complicated than its predecessor, MPEG-1 Audio, Layer 3, in that it does not have the hybrid filter bank.

The audio stream is compressed using an audio codec such as MP3, Vorbis or AAC.

* AAC support is provided by the faad2 library, supporting m4a files

A related transform, the modified discrete cosine transform, or MDCT ( based on the DCT-IV ), is used in AAC, Vorbis, WMA, and MP3 audio compression.

There is also an add-on package for Helix DNA Producer SDK with AAC or aacPlus encoding support.

Dolby is part of a group of organizations involved in the development of AAC ( Advanced Audio Coding ), part of MPEG specifications, and considered the successor to MP3.

Support for VBR in AAC and MP3 files is found in most modern digital audio players, including those released by Microsoft, Apple, Creative Technology, and SanDisk.

Serving as the focal point for all Air Force armaments, the AAC is the center responsible for the development, acquisition, testing, deployment and sustainment of all air-delivered weapons.

AAC or Dolby Digital Plus audio is transmitted at 320 kb / s for 5. 1 surround sound, with stereo audio at 128 kbit / s ; audio description takes up 64 kbit / s, subtitles 200 kbit / s and the data stream, for interactive applications, just 50 kbit / s.

The abbreviation MP2 is also sometimes erroneously applied to MPEG-2 video or MPEG-2 AAC audio.

* The Amateur Athletics Club ( AAC ) is founded and becomes the governing body of athletics in the United Kingdom, hosting the first national championships and introducing a definition of " amateur " that will determine eligibility for athletics competitions until the late 20th century.

As a result of these advantages, the MDCT is employed in most modern lossy audio formats, including MP3, AC-3, Vorbis, Windows Media Audio, ATRAC, Cook, and AAC.

is available, in selected languages, on audio compact disc and via download in MP3, AAC, PDF and EPUB formats.

Livingston is also home to ; two competitive swimming clubs, the Livingston & District Dolphins and the Aquanauts of Livingston ; Livingston and West Lothian Hockey Club, which has several men's and women's teams and provides junior coaching ; and two track and field athletics clubs Livingston & District AAC, and Lothian RC.

While it is not backwardly compatible with existing FM receiver equipment, with broadcasts digitally encoded using AAC, this ability to operate within the internationally agreed FM spectrum of 88-108 MHz makes DRM + a viable candidate for future adoption when countries begin to switch off their analogue broadcasts.

Modern use of AAC began in the 1950s with systems for users who had lost the use of speech following surgical procedures.

AAC interventions are highly individualized, taking into account specific abilities of language comprehension, social-relational characteristics, learning strengths and weaknesses, and developmental patterns for specific types of intellectual disabilities.

Aided AAC makes great use of symbols, particularly for non-literate users, as well as a large variety of input methods.

* m4p – A version of AAC with proprietary Digital Rights Management developed by Apple for use in music downloaded from their iTunes Music Store.

For example, uncompressed songs in CD format have a data rate of 16 bits / channel x 2 channels x 44. 1 kHz ≅ 1. 4 Mbit / s, whereas AAC files on an iPod are typically compressed to 128 kbit / s, yielding a compression ratio of 0. 09, for a data-rate savings of 0. 91, or 91 %.

Windows Media Player 12 adds native support for H. 264 and MPEG-4 Part 2 video formats, AAC audio and 3GP, MP4 and MOV container formats.

* Icecast – a free and open source streaming server for internet radio stations, supports formats AAC, MP3, Ogg Vorbis, Theora, and NSV

* SHOUTcast – a freeware server for internet radio stations, supports AAC, MP3, and NSV

It also allows the creation of elementary MP4 data streams and provides an audio codec for creation of AAC audio streams.

Prior to March 2009 digital music files with digital rights management were available for purchase from the iTunes Store encoded in a proprietary derivative of the AAC format that used Apple's FairPlay DRM system.

Transcoding from AAC to Dolby Digital or DTS and multi-channel output via HDMI was not originally necessary for Freeview HD certification.

for MP3 and MPEG-2 AAC, and

From 2004 until 2009, The Watchtower was released on CD in MP3 format ; digital files are now available for download in MP3 and AAC / M4B formats.

AAC is a perceptual coder suited for voice and music and the High Efficiency is an optional extension for reconstruction of high frequencies ( SBR: spectral bandwidth replication ) and stereo image ( PS: Parametric Stereo ).

Assistive technology ( also Alternative and Augmentative Communication devices ; AAC ) can be used to overcome physical barriers to manipulating books, and to augment speech motor and language difficulties ( e. g., type, or select symbols to identify rhyming words ), and cognitive impairments ( to provide needed support required for target skill acquisition ) ( Copeland & Keef, 2007, see chapter 9 ).

Neither AAC nor Dolby Digital Plus codecs are supported by most home AV equipment, which typically accept Dolby Digital or DTS, leaving owners with stereo, rather than surround sound, output.

Although these resulting raw AAC files were unplayable by most media players at the time of release, they represent the first attempt at circumventing Apple's encryption.

The research results of his dissertation are the basis of MPEG-1 Layer 3 ( mp3 ), MPEG-2 Advanced Audio Coding ( AAC ) and most other modern audio compression schemes.

It focuses on the Ogg family of formats, the most successful of which has been Vorbis, an open and freely licensed audio format and codec designed to compete with the patented MP3 and AAC.

The most commonly used mode is HE-AAC ( also called AAC +) that offers an acceptable audio quality somewhat comparable to FM broadcast.

Although these resulting raw AAC files were unplayable by most media players at the time of release, they represented the first attempt at circumventing Apple's encryption.

A technically better compression technique, MPEG4 ( more commonly known as AAC ) was subsequently developed and found favor with most commercial music distributors.

* AAC-LC ( the most widely used AAC profile defined in MPEG-4 Part 3 )

Affirming Catholicism is a movement operating in several provinces of the Anglican Communion, most notably in the UK, Ireland, the United States ( where it is known as Affirming Anglican Catholicism or AAC ) and Canada.

It is based on psychoacoustic lossy compression, the same principle being used in most modern lossy audio encoders such as MP3 and Advanced Audio Coding ( AAC ), and it allowed both broadcast automation and recording to hard drives.

* All U. S. Sony Ericsson phones – most Sony Ericsson phones should show up in SonicStage for MP3 / AAC transfer

From the time of its founding until the mid-1980s, candidates for membership in the AAC were required to submit a list of notable ascents at high altitude or other “ significant alpine accomplishments ” The phrase “… or the equivalent ” appeared at the end of this bylaw, allowing the Board to elect artists and writers with little tangible experience, but for the most part, membership in the Club meant that a person had already achieved a great deal in the world of mountaineering.

High-tech AAC aids permit the storage and retrieval of electronic messages, with most allowing the user to communicate using speech output.

Sensitivity to and respect of cultural diversity contributes to ongoing family involvement and to the selection of the most appropriate AAC system.

AAC has been produced for more than 70 years, and it offers advantages over other cementitious construction materials, one of the most important being its lower environmental impact.

Unlike most other concrete applications, AAC is produced using no aggregate larger than sand.