Handbook for Sound Engineers

140 Chapter 6

have a significant impact on the ability to accurately
perceive a stereo image.

Although Barron did not look at the effect of reflec-
tions arriving from below as in the case of a console
reflection, the effect is clearly audible. In 1981 C.A.P.
Rodgers^18 noted a similarity between the spectral
notches created as a result of loudspeaker misalignment
and those created by the pinna which have been shown
to play an important role in localization. She postulated
that the presence of spectral notches would impair or at
least confuse the auditory system’s ability to decode
position cues. This could explain the phenomenon noted

by Barron. The very early reflections are those that

cause notches similar in spectral positioning to those

caused by the pinna. These are the reflections that cause

image shifts.

6.8 Small Room Design Factors

The basic tools for looking at small room performance

have been addressed. We now turn our attention to

small room design factors. We have divided small

rooms into three broad categories; precision listening

rooms, rooms for microphones, and rooms for entertain-

ment. We are not trying to imply that there is only one

way to build a control room or an entertainment room.

There are different design criteria for different

outcomes. The categories presented here are not

intended to be exhaustive; rather they are intended to be

general and representative. It should also be noted that

we are not including the noise control issues that are

often an important part of room design. The reader is

referred to Chapter 3 for noise control information.

6.8.1 The Control Room Controversy

Since most control rooms are acoustically small, it is

appropriate to discuss control room design in general in

this context. Some insist that control rooms should be as

accurate as possible. Others insist that since music is

rarely listened to in highly precise analytic rooms,

recorded music would be better served if control rooms

were more like entertainment rooms; not so sterile, but

rather designed so that everything sounds subjectively

great. Indeed many recordings are made in rooms that

are not close to precision listening rooms. This debate

will probably never be resolved as long as there are

deductive and inductive reasoners, left-brain and

right-brain people, artists and engineers. In the next few

sections we are not attempting to solve this debate,

rather we are trying to set out some simple guidelines.

The most important task for the room designer is to

listen to the client and not make assumptions about

what it is he or she is looking for.

6.8.2 Precision Listening Rooms

These are rooms where the primary goal is for the

listener to have as much confidence as possible that what

is heard is precisely what is being or has been recorded.

Frequently, users of these rooms are performing tasks

that require listening analytically to the program and

making decisions or judgments about what is heard.

Figure 6-18. The effect of reflections bouncing off a studio
console. Measurement courtesy of Mathew Zirbes.

A. ETC of the "near field" loudspeaker

on a meter bridge.

B. Frequency response of the "near field"

loudspeaker on a meter bridge.

C. Frequency response of the "near field" loudspeaker

on the meter bridge with the console covered with

acoustical absorbent, removing the reflection.