# A better way to average frequency response?



## AudiocRaver (Jun 6, 2012)

John, have you ever considered the averaging function as in the following diagram? I have borrowed this diagram, with full appreciation and credit given to Denis Sbragion's _DRC: Digital room Correction_ site. 

It suggests that since we are more sensitive to response peaks than to narrow response dips and notches, an averaging function should weight the peaks more heavily than the dips, and our perception of frequency response will ride closer to the top of the closely-spaced variations than the middle, as we seem to assume.

The phenomenon would seem to address the popularity of target curves which roll off above 1 kHz or so to keep a room from seeming overly bright.

Any thoughts on the matter? Is the approach valid? Any possibility of an alternate averaging function for REW?









*Quoted from the DRC site.* "Example of a magnitude response envelope. The unsmoothed magnitude response of a typical room, corrected with a flat target, is plotted. Superimposed there is the usual smoothing, computed on the ERB scale, showing an essentially flat magnitude response, as expected. The magnitude response envelope, computed on the ERB scale too using standard parameters, show a rising slope which is in good agreement with the inverse of one of the target responses suggested in the literature."

Link to the DRC site.


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## JohnM (Apr 11, 2006)

Denis researches his approach thoroughly so I'm sure he has a sound basis for the methods employed, but there are a lot of tunable parameters in the DRC psychoacoustic target calculation so it's not at all straightforward to say what settings could or should be used to produce any particular response. I'm not convinced that this is an explanation for targets that roll off at high frequencies, since such targets reflect typical listening position measurement results - there is usually more absorption at HF in rooms.


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## AudiocRaver (Jun 6, 2012)

Is there any reason to believe that an averaging method that rides more toward the peaks might be more psychoacoustically accurate?


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## Wayne A. Pflughaupt (Apr 13, 2006)

I have my doubts. 

If you have speakers with bi-wiring terminals, here’s an easy test you can do that takes the averaging effect of a measurement system totally out of the equation. Play a pink noise signal through the tweeter, then mid/woof, and then your subwoofer, and measure each with a SPL meter with C-weighting. I’ll bet you a gift certificate for your favorite restaurant that you’ll find the subwoofer gets the highest figure, and the tweet gets the lowest. 

Regards,
Wayne


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## AudiocRaver (Jun 6, 2012)

Wayne A. Pflughaupt said:


> I have my doubts.
> 
> If you have speakers with bi-wiring terminals, here’s an easy test you can do that takes the averaging effect of a measurement system totally out of the equation. Play a pink noise signal through the tweeter, then mid/woof, and then your subwoofer, and measure each with a SPL meter with C-weighting. I’ll bet you a gift certificate for your favorite restaurant that you’ll find the subwoofer gets the highest figure, and the tweet gets the lowest.
> 
> ...


Sorry, Wayne, I honestly do not understand how your example relates to my question. No worries. I should have said smoothing, although averaging of some kind is involved in the smoothing algorithm, in the way a raw measurement sweep, with its wild high-frequency variations of 20 dB and more, is processed and what weighting is applied to the individual measurements, and over what averaging window, or band, to arrive at a smoothed version of the sweep.


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## Wayne A. Pflughaupt (Apr 13, 2006)

It’s possible I misunderstood your original post. To clarify, when you said...


AudiocRaver said:


> The phenomenon would seem to address the popularity of target curves which roll off above 1 kHz or so to keep a room from seeming overly bright.


...were you saying that you wonder if the more common way of averaging is why people typically roll out response above 1 kHz in their rooms (e.g. the black line that rides down the center of the graph, rather than the upper blue line)?

Regards, 
Wayne


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## AudiocRaver (Jun 6, 2012)

Was wondering if that might be a contributor to the phenomenon, as suggested by Denis S., DRC author. Understood there are other factors, like room liveness.

Example: I like a bright speaker when treble is smooth. Remember one where there was a TINY peak at around 4 k.with 6th-Oct smoothing that was bugging me. Unsmoothed, it was more like a 3 db peak, but very sharp. Seemed like the smoothing/averaging algorithm was hiding it, underemphasizing it. That was my original point, admit I did not state it clearly.


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## Wayne A. Pflughaupt (Apr 13, 2006)

AudiocRaver said:


> Was wondering if that might be a contributor to the phenomenon, as suggested by Denis S., DRC author.


Okay. That’s what I thought you were saying, just making sure I didn’t misunderstand.

Again, I have my doubts that the common way of averaging (i.e. down the blue line) would be the reason for people’s tendencies to introduce a curve to their systems that rolls out above 1 kHz. I think it’s just the way we hear. That’s what my little test outlined above was supposed to show, it takes the averaging performed by the measurement platform out of the equation. AFAIK the SPL meter does not do any averaging, or at least not that kind.




AudiocRaver said:


> Example: I like a bright speaker when treble is smooth. Remember one where there was a TINY peak at around 4 k.with 6th-Oct smoothing that was bugging me. Unsmoothed, it was more like a 3 db peak, but very sharp. Seemed like the smoothing/averaging algorithm was hiding it, underemphasizing it. That was my original point, admit I did not state it clearly.


That’s curious, because personally I _need_ some smoothing to “find” peaks like that. I couldn’t pick a 3 dB peak out of an unsmoothed graph (like in your opening post) if my life depended on in...

Regards,
Wayne


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## AudiocRaver (Jun 6, 2012)

Wayne A. Pflughaupt said:


> I think it’s just the way we hear.


Agree and disagree, all due respect to your experience and to expert studies. I find myself wanting less treble with speakers that have distortion or narrow-but-prominent frequency response peaks in that range (or general FR roughness) and wanting more treble with speakers that have low distortion and FR smoothness in that range. And my ears are fine, good out to 14 kHz.

I simply cannot help but believe that those elements are *at least contributing factors* to the overall "how much HF do people like" question. But that's just me.There are exceptions to every rule, and exceptions to the exceptions, and.......:bigsmile:


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## Wayne A. Pflughaupt (Apr 13, 2006)

Nevertheless, I’m still betting that if you try the experiment you’ll find the tweeter level to register a lower SPL reading than the mid/woofs. IOW, the curve (rolling off above 1 kHz or some point in the mid-range) will be there. I’d give it a run myself but I don’t have speakers with bi-wire terminals. :T

Regards,
Wayne


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## AudiocRaver (Jun 6, 2012)

I think we need to agree to disagree and move on, we are boring everyone else. I have one other thought, but will PM you.

MOVING ON.....


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