Room Analysis-How?

Lots of thoughtful and helpful feedback here. Thanks to everyone who has posted here thus far. 

@rjduncan - great question and one that involves a lot of learning.

EDUCATION: I'd suggest reading Dr Toole's book "Sound Reproduction" which is about acoustics and psychoacoustic stuff.  A base of knowledge and common sense will take you far.

TOOLS: While others here have recommended REW, I found that it has a steeper learning curve than OmniMic from Dayton Audio and which I prefer to use.  I also prefer it's graphical user interface but both tools should give you the same measurement results. 

While REW/OmniMic come with lots of different measurement charts, my analytical background has me importing the OmniMic measurements into Microsoft Excel spreadsheet for further data manipulation and additional calculations and added Charts.  For example, decibels are logarithmic values that should not be added or divided or multiplied together, so they need to be converted into linear energy first, then perform your arithmetic on them, and finally convert the result back to decibels; this is needed for frequency response and early reflections analysis primarily.  While subtracting a log value from another log value is fine (e.g. take the difference between L and R speakers to quantify their loudness variance across the frequencies), you'll need linear energy values for creating averages or sums such as to calculate "Error Rates" which represents the distance the measured frequency response for a channel is from your Target curve.  Another area of applying linear energy is with Energy Time Curve data for early reflections of 0-10ms which impacts tonal balance and imaging strength with the goal of having acoustical energy symmetry from 1st order and other reflections especially important in unsymmetrical shaped rooms.  More can be found in this article I wrote here:  https://pmamagazine.org/early-reflections-101-the-first-10-milliseconds-that-make-or-break-stereo-imaging/  Please excuse the shameless plug.

WORKFLOW SEQUENCE:  Acoustically Treating a Room - Is there a Work Flow that works best?

Many of us spend a lot of time (and money!) curating the perfect stereo or home theatre setup — reading reviews, visiting shops, asking trusted audiophile friends. Eventually, we piece together a system that should sound amazing…but then we bring it home, and it doesn’t sound as good as it did in the store.  The problem might not be your gear — it might be your room.

Acoustics play a huge role in how your system sounds. In fact, many pros say the room contributes about 50% of the final sound quality. That’s massive. So we start exploring acoustic treatments. Maybe we try a few DIY absorption panels, or maybe we're lucky enough to have a dedicated room where WAF isn't a factor and we can really experiment.

But here's the big question:
Is there a “right” order for treating a room?
Yes — and following a proper sequence makes a big difference.

Over the years, I’ve refined this workflow for both my room and my clients’.

 

• Early Reflections (0–10ms)
  Start with the floor, ceiling, sidewalls, front and rear walls — focusing on first-order reflections. These reflections arrive just after the direct sound and have the biggest impact on imaging and tonal balance.

• Bass Decay
  Use bass traps to reduce overly long decay times. Why? Bloated bass can mask midrange detail, so this step is crucial for clarity.

• Mid/High Decay Times
  Add diffusion and/or reflectors to maintain liveliness. Over-absorbing these frequencies can leave the room sounding dull and lifeless. You want a balance — not an anechoic chamber.

• Frequency Response EQ (the very last step)
  Once the room’s reflections and decay are under control, then (and only then) consider gentle EQ. Aim for each channel to be within ±3dB across the range. Doing EQ first often masks deeper acoustic issues — it’s like painting over a cracked wall.

Most people start with EQ… but trust me, it’s better saved for last.

Here are 2 articles I wrote about taking and deciphering measurements:
https://pmamagazine.org/analyzing-a-stereos-frequency-response-and-decay-times/

https://pmamagazine.org/deciphering-stereos-acoustical-measurements-and-taking-corrective-actions/

Hope this helps . . .

@rjduncan - at the risk of appearing verbose given my long post above, I thought the following testing might be of interest to you.
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I wanted to evaluate how music sounds using 3 different EQ correction scenarios. This wasn’t an advanced scientific experiment—just a practical comparison for my ears.

Test Scenarios

· Measurements taken using 1/6th smoothing: 6 PEQ filters per channel below 500 Hz, optimized by OmniMic.

· Measurements taken using 1/12th smoothing: 6 PEQ filters per channel below 500 Hz, optimized by OmniMic.

· Measurements taken using 1/24th smoothing: 6 PEQ filters per channel below 500 Hz, comparing OmniMic’s settings to Kevin’s (my own) manual PEQ settings.

Listening Impressions

Here’s what I heard:

· 1/6th smoothing and EQ: The sound was dull, less engaging, and lacked dynamics.

· 1/12th smoothing and EQ: The sound was wonderful—dynamic, clear, and highly detailed.

· 1/24th smoothing and EQ: The sound was slightly more refined and polished than 1/12th, but possibly a touch less dynamic and engaging.
 

A Common Baseline for Comparison

To compare the results more fairly, I applied EQ corrections and then smoothed the 1/12th and 1/24th measurements to 1/6th smoothing—the “lowest common denominator.” Even at this level of smoothing, the results ranked as follows:

· 1/24th smoothing was the best on paper.

· 1/12th smoothing was a close second.

· 1/6th smoothing was noticeably worse.

EQ Adjustments: Cuts and Boosts

I also tallied the total cuts/boosts across the 12 PEQ filters:

· 1/6th smoothing: Total of 20.9 dB (average cut/boost: 1.9 dB).

· 1/12th smoothing: Total of 57 dB (average cut/boost: 4.4 dB).

· 1/24th smoothing: Total of 48.5 dB (average cut/boost: 4.0 dB).

This tells me that:

· 1/6th smoothing oversimplifies the data, hiding peaks and nulls. The result? Smaller EQ adjustments that are insufficient and leave the sound quality lacking.

· 1/24th smoothing reveals far more detail, including larger peaks and nulls, leading to more aggressive EQ adjustments.

Key Points

· Too much smoothing (like 1/6th) masks real issues in the frequency response, causing under-correction and dull sound.

· Too little smoothing (like 1/24th) exposes a lot of detail, which can require higher amounts of EQ. While it refines the sound, it may sacrifice some engagement and dynamics.

· 1/12th smoothing strikes the best balance—it exposes enough detail for meaningful corrections while preserving clarity, dynamics, and musicality - it was my "Goldilocks zone."

Final Thoughts

In my experience, what measures best doesn’t always sound best. For my ears, 1/12th smoothing and its corresponding EQ settings hit the sweet spot. It produced the most enjoyable and balanced sound without overdoing the corrections.

Thanks to everyone that chimed in on this thread.  My wife was out of town this weekend which gave me the opportunity to spend a lot of time on Saturday and Sunday becoming a novice, yet capable user of REW and analyzing my room.  I also bought the Master Handbookf of Acoustics and began to read.  I've already learned a ton!  My analysis this weekend led me to make meaningful changes to my main speaker positions and primary listening spots.  I made sub woofer adjustments in the crossovers and volumes.  I experimented with moving certain furniture around.  I had a large null in the 200-230HZ range in the beginning that I've now worked to an acceptable level.  And then after all the adjustments I applied my ears and tweaked a little more.  My room, which was impressively pretty good before I even started this analysis (dumb luck I suppose, perhaps helped by a wife with good furniture/decoration taste and placement!) sounds better than ever!  This will be iterative over time.  I'm guessing I'll experiment with panels, diffusers and traps as time goes on.  Who knows.  But this was fun, my room is better today and I'm thankful to those of you who posted to encourage and guide my endeavors in acoustical analysis!

@rjduncan   Fantastic!! It is amazing how we may have settled into what we thought was good sound, only to discover it can get better with minimal effort!

Keep us posted.