User Manual

Multichannel Monitoring Tutorial Booklet (M2TB) rev. 3.5.2

Masataka Nakahara : SONA Corporation

41 / 74

3-5. Playback image compatibility with the playback environment

Differences in surround speaker placement and the spread between the L/R speakers rarely cause

profoundly different results in the playback image when a surround production is played back. Thus, the

end user can enjoy most surround productions even if their setup is not, for example, the ITU-R

configuration.

However, compatibility of the speaker placement does become important when creating musical

productions in which you intend to skillfully use the phase relationships between channels to generate a

precise sound field. Including situations in which such needs must be supported, it is sometimes necessary

that a certain “standard” be maintained in the production playback environment. The typical example of

this case is Rec. ITU-R BS. 775-1, and it is important to consider ITU-R as the primary basis for the

surround playback environment. On the other hand, there are cases in which room shape, room size, and

the production content cause disadvantages if you attempt to apply Rec. ITU-R BS. 775-1 to the

production environment, and in such cases, it is valuable to consider other placements. For example in an

extremely narrow environment, the ITU-R surround speaker placement immediately beside the listener's

ears may create an unnatural-sounding playback.

Although “standard placement” is an important element of the playback environment, it is also important

that the engineer find it easy to carry out the mixing process. It is important that the mixing engineer

engage in surround production in an environment in which he finds it easy to mix, and creating the multi-

channel product with consideration of compatibility with other speaker placement.

To ens ure this, it is important to understand the characteristics of various speaker configurations. Also, in

actual production, variances in playback image due to differing speaker configurations can be minimized

if signals highly correlated with other channels are kept out of channels (speakers) whose location is

indeterminate. For example in the case of L/R, it is easy to obtain equivalent playback even between a

variety of playback environments, so using highly correlated signals is not a problem. However for L/R

and C, or for L/R and LS/RS, different environments will have these located in different positions, so if

highly correlated signals are used, there is a danger that the playback image or playback response may be

significantly different. Caution is necessary if you're using a lot of delay processing to create a sound field,

or when using production methods in which the correlation between speakers (channels) is important.

[Fig. 28] Correlation images of the playback signals and Compatibility between different listening environment

L/R

Robust

Severe

LS/RS

L/R

LS/RS

Compatibility between

different listening environment

Low

High

Correlation of

the playback signals

( L/R vs C vs LS/RS )