How to diagnose the need for room treatment?

In the bass, the arrival/decay times are more easily measured and corrected whereas at higher frequencies room mode interactions approach randomness. Thus, at those higher frequencies, only FR adjustments are feasible.

Yes, at higher frequencies only FR adjustments are feasible, but the point I was trying to convey is that making those FR adjustments on the basis of measured flat frequency response, in response to continuous tones monitored only in the frequency domain, will not provide best results. Listening to music provides the last (and most important) word in that part of the spectrum, it seems to me.

Arrival times in the deep bass assume importance particularly because of reinforcement and standing wave issues, as everyone probably realizes. Which causes the measured (and heard) amplitude of deep bass to vary as a function of frequency and location in the room, and which can be more easily corrected on the basis of measurement, as you indicated.

Regards,
-- Al

Hi KR4, That is true. But first one has to identify the problems. How you correct it and how much you wish to achieve is up to each audiophile.

The problem I see is that, very few know what they are dealing with, as far as in room response is concerned.

Bob

FWIW, in my post I referred to 'smooth FR' but I purposefully did not say 'flat FR'. Flat suggests to me hearing all frequencies at the same SPL, and when I have heard sounds in a room that were measurable as flat (especially from speakers which allegedly had a flat FR) the result was too much upper-mid and high frequency energy, where as a 'smooth' albeit tilted FR could be much more realistic for most installations.

Personally I really detest peaky mid-range and upper midrange FR, and it is easy thru measurements to determine whether this is attributibutibe to the speaker or the room (or both) by doing both near field and listen position measurements. Am I wrong, or am I missing the point?

Newbee -- I don't think you are missing the point, you are just making some additional points.

To re-state my basic point, room effects at mid and high frequencies are heard differently by microphones + sound level meters than by the human hearing mechanism. The human hearing mechanism tends to some degree to "latch on" to the leading edges of transient waveforms, and give them greater emphasis than what may follow a few milliseconds later. I think that is pretty well recognized. But a microphone + sound level meter monitoring a continuous frequency sweep, or a series of tones covering the different parts of the spectrum, will not do that -- the late arriving sounds at any given frequency will be taken into account, so to speak, simply based on their amplitude. Therefore, whatever the desired tilt of the fr may be, tuning the room or the system to provide it on the basis of that measurement technique will not give the desired result when listened to by a human.

Regards,
-- Al

How about a dumb question :)

I am going to try Room EQ wizard with a good microphone placed at ear level where I normally sit. Do I aim the microphone at the front of the room (HDTV) or do I aim it at the ceiling?

I will be trying to analyze (and perhaps improve) my 5:1 theater system.