2
2. Sound Fields
Sound Fields
Direct Soundwave
Early Soundwave
Reflection
Late
So
und
wa
ve
Reflection
FIGURE 2-1 - Soundwave Reflection Diagram
STAGE
What is a Sound Field?
Each venue, be it a concert hall, cinema theater or small jazz club, has a characteristic “sound field” made up of
direct sounds and reflections from the surfaces of the environment. Some venues sound large and spacious,
others sound small and intimate. These characteristics are captured using special microphone pickup systems
placed in the actual venue. The microphone pickup system captures the acoustic blue print of the venue, which
contains all of the acoustic information about the venue, such as direct sounds, early reflections and reverberations
(reverberations occur when the number of reflected sound-waves arriving at the listeners ear becomes very
large; ref. Figure 2-1). All the acoustic data about the venue is stored in the computer and then downloaded to
the A/V receiver’s microprocessor internal memory. So when you select the concert hall sound field on your A/V
receiver, the information stored in the microprocessor’s internal memory is activated and your living room takes
on the characteristics of an actual concert hall.
Sound Field Types
Auto Format Decoding (press AFD button)
This mode automatically detects the type of audio signal (Software Format) being input (e.g. Dolby Digital, Dolby
Pro-Logic, or Standard 2 Channel Stereo) and performs the proper decoding if necessary. This mode presents
the sound as it was recorded/encoded, without adding any sound field effects.
NOTE:
This mode can be used as a reference. Set the equalizer to “OFF” while using this mode to hear the
source sound exactly as it was recorded. This mode can also be used to determine exactly what type of Software
format is encoded on a given disc.
2 Channel (press 2CH button)
Outputs the sound from the front left and right speakers only. Standard two channel (stereo) sources completely
bypass the sound field processing. Multi-channel surround formats are down-mixed to two channels.
NOTE:
No sound is output from the sub-woofer (LFE) when the 2 Channel mode is selected.
Normal Surround
This mode is designed to be used with a Multi-channel surround audio input (e.g. Dolby Digital/AC-3, DTS or
Dolby Prologic) and the normal six-speaker surround system (front left/right, rear left/right, center and LFE) (ref.
Figure 2-2). When the playback material is encoded with multi-channel surround audio, it will be heard as it was
originally recorded (with no other processing for special effects). For example, a movie will be played back
exactly how the producer recorded it during the movie’s production. If Dolby Prologic (2 channel audio) encode
material is input, it will be processed to create surround sound effects using the actual six-speaker system.
Summary of Contents for STR-DE845
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