(audio) Loudspeaker And Listener Positions For Optimal Low-Frequency Spatial Reproduction In Listening Rooms (David Griesinger).pdf

Loudspeaker and listener positions for optimal low-frequency
spatial reproduction in listening rooms.

Author: David Griesinger
Location: Lexicon, 3 Oak Park Dr., Bedford, MA 01730-1441
Abstract:
This paper will briefly describe the physical and physiological mechanisms that enable
low-frequency externalization and spatial reproduction in listening rooms. These
mechanisms depend on reproducing a time-varying interaural time difference at the
listening position through interference between symmetric and asymmetric room modes.
The effect works essfully when the symmetric and asymmetric room modes are
driven by independent portions of a multi-channel signal, typically the in-phase and the
anti-ponent of a two-channel recording. The paper will describe how this
overlap can be optimized by adjusting the loudspeaker and listener positions for a variety
of playback rooms. The results show that mon room shapes yield low
spatiality regardless of loudspeaker and listener positions.


Introduction:

This note attempts to cut through some of the confusion and contradiction around the
subject of loudspeaker placement in rooms, with an emphasis on reproduction of spatial
information. This subject is inherently contradictory, as the placement that is optimal for
spatial properties might be different than a speaker placement that is optimal for low
frequency response smoothness. The advent of home theater, with the requirement of
modating a large screen, has made the situation even plicated.


Spatial perception of reverberation

Before discussing how room modes allow us to hear spatial properties in a recording, it is
well to briefly discuss how spatial properties of a hall are perceived at low frequencies.
This subject is extensively discussed in reference [1] and [2], and will be summarized
here. When we are in a large reverberant space such as a concert hall, low frequency
sounds – par