Audioden

1. A-B Test

A test between two components. For example, a test between two different loud speakers.

2. A-Weighting

Measurement based roughly on the uneven frequency sensitivity of the human ear. The influences of low and high frequencies are reduced in comparison to midrange frequencies because people are most sensitive to midrange sounds.

3. AAD

An acronym found on CD cases to indicate that the music was recorded and mastered on in analog (AA) and then stored digitally (D). (See also ADD) (See also DDD)

4. AC

Alternating Current. An electrical current that periodically changes in magnitude and direction.

5. AC3

Audio Codec 3. This was the original and more technical name for Dolby Digital. Replaced by marketing mavens when they realized that Dolby's name was not in the title. Some RF modulated, 5.1-encoded laser discs were labeled as AC3. Later versions were labeled as Dolby Digital. (See also Dolby Digital)

6. Academy Curve

An intentional roll-off in a theatrical system's playback response above ~2kHz (to -18dB at 8kHz) to minimize noise in mono optical tracks. Some (many) transfers to home video of mono movies have neglected to add the Academy filter during transfer, giving many old movies a screechy sound they were never intended to have. A few home processors have an Academy filter option, making them a must for old-movie buffs. Has been used since 1938.

7. Acoustic Suspension

A sealed or closed box speaker enclosure.

8. Acoustically Voice Matched

Ensuring that the many different loudspeakers used in a Home Theater system have a sufficiently similar timbre match, such that when a sound is panned between them there is no change in character of the sound.

9. Acoustics

The area of study which deals with the behaviour of sound. Also the effect a given environment has on sound.

10. Active

Powered. An active cross-over is electrically powered and divides the line-level signal prior to amplification. An active speaker includes an active crossover and built-in amplifier.

11. ADD

An acronym found on CD cases to indicate that the music was recorded in analog (A) and mastered or remastered digitally (D) and then stored digitally (D). (See also AAD) (See also DDD)

12. AES/EBU

AES/EBU (Audio Engineering Society/European Broadcasting Union) is the name of a digital audio transfer standard. The AES and EBU developed the specifications for the standard. The AES/EBU digital interface is usually implemented using 3-PIN XLR connector.

13. Alignment

A class of enclosure parameters that provides optimum performance for a woofer with a given value of Q.

14. Alpha

In sealed enclosure designs, the ratio of Vas to Vb, where Vb is the volume of the box you will build. See also: Sealed Enclosure

15. Ambience

The acoustic characteristics of a space with regard to reverberation. A room with a lot of reverb is referred to as being live; whereas a room with little or no reverb is considered to be dead.