INDEX A ABR . See Auxiliary bass radiator (ABR) Absolute threshold , 558 AC . See Alternating current (AC) AC-coupled amplifiers advantages in , 278­279 Accumulation of information , 558 Acoustical power , 64­66 Acoustic gain equalizers , 544 Acoustic impedance in loudspeaker , 337­338 Acoustic labyrinths , 388­393 cone excursions , 391 infinite pipe , 390 low frequency pipe , 390 modern transmission lines , 391­393 Acoustic materials, density of , 589 Acoustic reflex , 33 advantages of conventional , 299 class-A , 271 class-AB , 271 class-B , 271 class-C , 271 class-D , 271­272 class-E , 272 class-F , 272 class-G , 272­273 class-H , 273­274 class-S , 274 current-drive , 274 DC-coupled , 279­281 distortion mechanism capacitor distortion , 301 induction distortion , 301 input stage distortion , 301 NFB takeoff distortion , 301 non-existent distortions , 302 Audio editors, loop-based , 483 Audio Engineering Society (AES) , 189 Audiograms, of normal and damaged hearing , 47 Audio groups , 112 in audio mixer , 142 Audio program material monitoring , 21­22 Audio-Technica model AT3090 microphone , 83 Auditory canal , 30 Auditory filter derivation of response of , 37 idealised response of , 38 Automation, audio mixer , 130­139 in digital mixers , 136­138 dynamic and static systems , 134­135 fader , 129­132