Description; General; Iva- Indivicual Virtual Acoustics; Dolby Surround Pro Logic Decoder - AKG HEARO 777 SURROUND Mode D'emploi

3 Description

3.1 General

The HEARO 777 SURROUND headphone system
• uses state-of-the-art UHF radio transmission technology;
• uses automatic gain control (AGC) to modulate the transmitter RF section for high transmission quality;
• connects to any audio, video, TV set, or PC with a headphones or line output;
• provides perfect sound reproduction, full mobility, and signal transmission through walls and ceilings over a distance of up to
330 feet (100 m);
• features an "Autotuning" function that automatically tunes the headphones to the transmitter frequency for optimum reception;
• uses proprietary IVA technology for exceptionally realistic, three-dimensional listening;
• features an integrated Dolby Surround Pro Logic decoder for perfect reproduction of hi-fi, TV, PC, or video sound in Dolby
surround format;
• provides an analog line output for connecting an external headphones amplifer for hardwire headphones.
The HEARO 777 SURROUND system is available for two different LPD frequency bands: 914 MHz for the US and
864 MHz for various European countries (864 MHz version shown on the cover).
The HEARO 777 SURROUND system lets you share your listening enjoyment with other persons. You can operate your transmitter
with several headphones simultaneously. Make sure to use wireless headphones operating in the same UHF frequency band as the
HEARO 777 SURROUND.
3.2 IVA - Individual Virtual Acoustics
One drawback of headphone listening is the psychoacoustic phenomenon of "inside localization": the orchestra seems to play inside
your head rather than in the room. AKG developed a binaural audio processing techniquecalled IVA (Individual Virtual Acoustics) that
models the way the head and pinnae change the arriving sound waves (ear matching function). Thus, the various sound sources will
seem to be located outside your head even when you are using headphones.
LH FILTER
RH FILTER

3.3 Dolby Surround Pro Logic Decoder

The Dolby Surround Pro Logic decoder integrated in the transmitter uses the stereo input signal to derive two additional signals, a center
and a surround channel. The IVA circuitry generates from these signals a binaural signal equivalent to reproduction through five high qua-
lity loudspeakers (3 front, 2 rear speakers). This allows you to enjoy all the benefits of Dolby surround sound even through headphones.
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 localized 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.
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