Originally Posted by raddle
What is an "even sound field" in objective, measurable terms?
"Balanced frequency response from the main listening position"? You mean the in-room response including all reflections? What's the time window? Reflections out to how many ms? Is this more important than the portion of the impulse that contains no reflections (direct sound) or the anechoic chamber response? Can you provide an objective, absolute justification for all answers? What's the polar sensitivity pattern of the microphone you use to measure the frequency response? Can you justify all these choices objectively?
An even sound field from left to right is an even dispersion. If you slowly potted a tone from left to right, it would cross the room smoothly without changing in volume, particularly in the middle (phantom center).
Time delay isn't an issue in typical living rooms, only train stations and baseball stadiums. By the way, hall ambiences aren't measured in ms, they are measured in seconds. A typical concert hall will have a two second decay from the original sound to the point where the volume drops 60dB (the point that most acousticians use for measuring such things.)
A balanced frequency response from the main listening position means that a tone sweep throughout the audible spectrum remains at a consistent sound pressure level throughout. This is taking into account both the response of the speakers and the effects of the room on the sound they produce. You calibrate this through room treatment and equalization and measure it with an SPL meter, or just tune it by ear.
The sensitivity of any testing or measuring equipment used doesn't really need to be any better than human ears, but many are much better. So it isn't an issue.
Edited by bigshot - 1/20/14 at 7:37pm