Threshold of audibility of listening room changes

I had an interesting experience this morning.

I live in a village between Albuquerque and Santa Fe so, pre-COVID, I spent lots of time driving to meetings in these cities. Over the last year, much of that time has gone to improving the sound of my music system–chiefly by dealing with issues in my music room.

In contrast to my earlier efforts, this time I kept detailed notes on each change made. For example, in toe-in, in the distance between my listening position and speakers, and in the height of my chair. This has enabled me to learn how small a change needs to be before I can hear a difference. What I learned is that even a tiny change can make a big difference. Nevertheless, today’s change was a surprise.

I use Acoustic Science’s “Iso-Thermal Tube Traps” to deal with room peaks and phase issues. Each tube trap has, at one end, two nail heads—one inch apart—on its top rim. These make it easy to determine that pairs of traps on either side of the room are pointing in the same direction.

The pair that is closest to the main speakers was set so I could see one of the nail heads but not the other. Listening to Reference Recordings “Testament” (Turtle Creek Chorale and Dallas Wind Symphony, RR-49 disk, also streaming on Tidal and Qobuz) the winds sounded fine but the chorus was too deep in the room, so it lacked presence and impact. I already had learned that a small rotation of aTube could make a difference, so I rotated the 13” diameter tube just enough so that, from my chair 9 feet away I could see both nail heads.

To say that this tiny change made a difference would be a gross understatement. Suddenly I was in Meyerson Hall with the wind ensemble and the chorus. Now, the chorus was just behind the winds (as shown in the photo in the notes). Single instruments were barely audible while double fortes shook the room.

This is only one of the surprises I’ve had over the last few months, especially after using Octave Records Reference Music Track 7 to get my sub and main speakers phases precisely aligned. For example:

  • Height of listening position: I can hear a change when I raise the listening position by 3/16”
  • Difference in distance from listening position to center of tweeter on the two main speakers: 0.5 cm.
  • Hz at the center of crossover between sub and main speaker: plus or minus 2 Hz.
  • Toe-in of main speakers: less than 1 degree.

I don’t claim any special hearing abilities. And change does not mean improvement. I’m lucky to have a dedicated listening room and equipment that allows for small, repeatable changes. But I continue to be surprise by how tiny changes in a room can make such a big difference in what I hear.


Yes it is stunning how micro changes in the room can make such a difference. I built 13” tube traps, copies of the ASC’s, and they made a difference.
Sadly, I have yet to get that perfect sweet spot. I have dipole speakers in a basement that still excite
nasty room nodes. Nice to hear that you got your sound and you were up to the challenge.

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Hey jrango…

While my own listening space is simple without any
room treatments…

Have myself found that the smallest of change in speaker
placement yields an extraordinary improvement to the
sound stage quality…

Indeed yes on sound quality improvements that you have

My listening space is 15’ x 25’ L shaped…with a very quiet
noise floor ranging 27 to 30 dbs…Listening with an average of
60 dbs loudness…subtleties in quiet passages are very evident.

Sometimes though, it seems that a lower threshold exists in the music
and at times eludes me. My system though, is very nuanced with
very good detail

Room treatments are an art - science that should be easy to grasp
yet a challenge when reading about them…

One day perhaps venturing into such will come
to pass…

Appreciate your review of your listening space