What is the target frequency response/curve of a well treated room?

[Auditory Cortex]

Hi. I have seen many posts and articles where they show how to analyze and get flat response curves for speakers. However, none of them show how the frequency response of a well treated room looks like.
Then I found this video:

And from what I understand is that, flat frequency response studio monitors inside an average room, will get a frequency response for the room where the low end is above the mids, and the high end would be below the mids. This is apparently how most of the listeners listen to music.

In the past I have calibrated my headphones getting some EQ settings from internet that makes them to have a flat response, but I always felt that they sound very bright and very weak in the low end, its a frequency curve that sounds very unmusical to my ears, so I always end up EQing them again to my taste, and I always do the same, increase the low end and diminish the high end, so then all the music sounds perfectly good for me.
If I compare the frequency curve of my personal taste then I find out that it actually resembles the shape of the Harman curve that is shown in the video,

so this made me wonder what is then the frequency response of an average music studio room? Not the studio monitors, BUT the speakers AND the room, what is their shape? do it resembles the Harman curve, or is flat?

 

[Thomas_A]

This will vary depending on studio and whether you take the measurement at the near field monitors or a far field setup. There is a paper from Genelec where they did some measurements.

 

[MaxwellsEq]

You can't easily compare a control room acoustic to a home acoustic. The soundproofing is usually many inches deep. The main monitors are often flush-mounted. There is often a console in the approximate middle of the room. There are often midfield and nearfield monitors. The room is usually heavily isolated from the rest of the building. The door is very heavy and often there are back-to-back doors to allow an airlock.

 

[holdingpants01]

the curve you posted is generally the goal as a shape, but some prefer no HF roll off (me), some prefer as much as you can see, same with the low end. I have speakers corrected to a flat line with a shelf 3dB boost below 200Hz, so the flat line from your graph below 300Hz and the dotted line above. This is because I work rather quiet, around 80dBSPL is loud to me, so I stay below that and I need high and low frequencies to come through. What's almost universally true is that flat response at the listening position is just bright and with no weight to the sound, because no one mixes or master with this target in mind

 

[Bjorn]

Within 2-3 dB with 1/24 Oct smoothing is considered excellent. And most would say a minimum target should be within 5 dB.

Time domain behaviour is likely equally important. Early arriving reflections should be attenuated with minimum -20 dB but ideally to -25/-30 dB. Later reflections diffused if room is sufficiently big enough and if it's for music, though there are different approaches and design ideas here.
Low mids and bass need to have a short decay with few resonances and ringing.

 

[Thomas_A]

You can't easily compare a control room acoustic to a home acoustic. The soundproofing is usually many inches deep. The main monitors are often flush-mounted. There is often a console in the approximate middle of the room. There are often midfield and nearfield monitors. The room is usually heavily isolated from the rest of the building. The door is very heavy and often there are back-to-back doors to allow an airlock.

I think you can compare them through measurements. But a control room response will look and sound different from the home situation.

ATC speakers / Monitors

Tangband, I think you missed the point. Or didn't read. Trapped in an odd loop. This is the test, it was in my post. Page 80. https://americanradiohistory.com/Archive-HiFI-Stereo/80s/HiFi-Stereo-Review-1987-01.pdf It's quite famous. The ability to differentiate amps was measured. And...

www.audiosciencereview.com

 

[thewas]

The frequency response at the listening position depends also on the loudspeaker directivity and listening distance so there is not a unique answer to that question, except that the direct sound should be ideally flat and the directivity smoothly continuous.

More useful reading material about it can be found here:

Some comments from Floyd Toole about room curve targets, room EQ and more

Room curve targets Every so often it is good to review what we know about room curves, targets, etc. Almost 50 years of double-blind listening tests have shown persuasively that listeners like loudspeakers with flat, smooth, anechoic on-axis and listening-window frequency responses. Those with...

www.audiosciencereview.com