Dolby Surround Pro-Logic Decoder - AKG HEARO 999 AUDIOSPHERE II Manual De Instrucciones

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• Dolby Surround Pro-Logic Decoder for perfect reproduction of hi-fi, TV, PC, or video
sound in analog or digital Pro-Logic surround formats;
• Dolby Digital decoder for optimum reproduction of DVD multichannel sound (AC3);
• VMAx for surround sound from a single pair of loudspeakers.
One drawback of headphone listening is the psychoacoustic phenomenon of "inside local-
ization": the orchestra seems to play inside your head rather than in the room. AKG de-
veloped a binaural audio processing techniquecalled IVA (Individual Virtual Acoustics) that
uses so-called "ear matching functions" to model the way the head and pinnae change the
arriving sound waves. Thus, the various sound sources will seem to be located outside your
head even when you are using headphones.
LH FILTER
RH FILTER
The Dolby Surround Pro-Logic decoder integrated in the HEARO 999 AUDIOSPHERE II de-
rives a center and a surround channel from a Pro-Logic encoded stereo signal. The IVA
processor converts these signals to a binaural format equivalent to that reproduced by four
high quality loudspeakers (3 front, 1 rear speaker). This lets you enjoy the 360° listening expe-
rience of Dolby Surround even through headphones.
The HEARO 999 AUDIOSPHERE II uses an authentic Dolby Digital decoder licensed by Dolby
Laboratories, Inc. The unique combination of a Dolby Digital decoder and IVA processing
allows the simulation over headphones of five loudspeakers exactly at the positions speci-
fied by Dolby. All five loudspeaker channels provide full-bandwidth audio, and the high sep-
aration as specified by the Dolby standard prevents comb filter effects.
The HEARO 999 AUDIOSPHERE II derives the surround simulation from the unprocessed
input signal with no added spatial effects, so you will perceive the same acoustics over head-
phones as you would in the theater. This will preserve the original atmosphere of every movie
unchanged.
The VMAx processor enables a single pair of loudspeakers to provide surround sound.
Similar to IVA, VMAx processing derives three-dimensional sound from analog or digital input
signals. VMAx will simulate the appropriate loudspeakers for Dolby Surround Pro-Logic and
Dolby Digital encoded input signals.
VMAx also allows you to increase the virtual distance between closely spaced stereo loud-
speakers (e.g., speakers placed next to a computer monitor).
The processed signal is available at the analog audio output so you can use a standard stereo
amplifier to reproduce the VMAx signal.
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A: Natural hearing: Due to the effect of the head and
pinnae, sound waves arriving at one ear differ from
those arriving at the other. Amplitude and phase
differences create a sense of spatial hearing.
B: Listening through headphones: Amplitude and phase
differences are eliminated. Sound sources are local-
ized inside the head rather than in the room.
C: Listening through headphones with IVA processing:
The ear matching function modifies the audio signals
at the ears to resemble diagram A. This restores
natural, spatial hearing.
2 Description
2.5.1 IVA Individual
Virtual Acoustics
2.5.2 Dolby Surround
Pro-Logic Decoder
2.5.3 Dolby Digital
Decoder
2.5.4 VMAx Processor
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