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Academy Curve: An equalization method standardized by the Academy of Motion Picture Arts and Sciences in 1938 and applied to the standard monaural track then used for sound in film, also known as the N (normal) curve. The response is flat between 100Hz and 1.6kHz. Response is reduced 7dB at 40Hz, 10dB at 5kHz and 18dB at 8 kHz. The severe reduction of the high end of the spectrum was specifically designed to conceal the high frequency crackling noise inherent in early film sound production. The intent of this specification was to ensure that the sound quality of motion pictures was consistent from theater to theater. Prior to the establishment of the Academy curve specification, thousands of movie houses had limited amplification and loudspeaker configurations and relied on custom equalization to shape their sound projection, which was less expensive. An expert engineer sat in the auditorium with a set of variable tone controls rather like a graphic equalizer. When he was satisfied that the best results were being obtained from the samples, the frequency correction was measured and built into the amplifier system. This method was not entirely satisfactory since many theaters contained acoustic defects, which could not be corrected by equalization. The Academy of Motion Picture Arts and Sciences set up a committee to study the standardization of theatre sound equipment. A test reel was prepared containing samples of dialogue and music from the major studios, and after repeated running in several theatres the final characteristics were established. Amazingly, despite consistent improvements in amplification and loudspeaker technology, the Academy Curve remained in effect almost 50 years.

A & R	A-B Stereo	A-Time
A-weighted	A440	AAC - Advanced Audio Coding (also MPEG-2 AAC)
AAF	Abalone	ABS
Absolute Phase	Absorption	Absorption Coefficient
Alternating Current (AC)	AC-1	AC-2
AC-3	Academy Curve	A cappella
Accent	Access Time	Accidental
Accompaniment	Accumulator	Acetate
Acoustic Lens	Acoustic Suspension	Acoustic Treatment
ACPI	Action	Actionflo
Active	Active Sensing	Actuator
Adagio	ADAT	ADAT/FST
ADAT Optical	ADB	A/D Converter (ADC)
Additive Synthesis	Adjusto-Matic	ADPCM
ADR	ADSR	Aeolian Harp
Aerophone	AES	AES/EBU
AES3	AES3id	AES42-2001
AFL	AFM	Aftertouch
AFTRA	AGC	Aggregate Device
Aging Toner	Agitato	AGP
AHDSFR	AIFF (Audio Interchange File Format)	AIR
AIT	Alder	Alder
Aleatoric Music (Composition)	Algorithm	Alias
Aliasing	Alkaline Battery	All-Button Mode
All-Notes-Off	Allegro	Alnico
Alteration	Altered Chord	Alternate Tuning
Alto	AM	Ambience
Ambisonics	Amen Break	Amperage
Ampere	Amp Head	Amplifier
Amplifier, Instrument	Amplitude	AMS
Analog	Analog Sequencer	Analog Synthesizer
Anamorphic	Andante	Anechoic
Anode	Anodize	Anodized
ANSI	ANSI A-Weighting	Antecedent and Consequence
Antenna	Antenna gain	Anti-Imaging Filter
Anti-Aliasing Filter	Anti-node	Aperiodic
API	Apoyando	Apple Talk
Application (Program)	Architecture	Archival Stability
Archtop Guitar	Arco	ARP Avatar
Arpeggiator	Arpeggio	Arrangement
Articulation	Artificial (or Automated) Double Tracking or ADT)	ASCAP
ASCII	Ash	Ashtray Bridge Cover
ASIC (Application Specific Integrated Circuit)	ASIO	Aspect Ratio
Asperity	ASPI	Asynchronous
ATA	ATA-2	ATA 66/100/120
ATAPI	Absolute Time Code	Atonal Music
ATRAC	ATRAC	Attack
Attenuation	Audio	Audiobook
Audiology	Audio RIP	Audio Suite
AudioUnits	Audiowire	Auditory Cortex
Augmented Interval	Auranomic	Author
Authorize	Auto Accompaniment	Autolocate/Autolocator
Automata	Automatic Mixer	Automation
Auto Punch	Aux Send	AVI
AWG (American Wire Gauge)	AWM	Axe