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Where is the science in EQ of headphones?

Aerith Gainsborough

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Ask them. I'm sure they would be happy to explain to you. I find it funny how you are willing to believe without evidence the bold assertion on here that high SPL (sub)bass frequencies won't cause hearing damage because our hearing threshold is high there, an inference that is not supported by known auditory physiology, yet you require much higher standards of evidence from an actual audiologist whose position is grounded in this known biology.
Well, to be honest, that's usually what happens if you go against the grain and present results/hypothesis that question well established facts/beliefs.

Not just in the realm of science.

While your linked study is interesting, I'll be frank enough to tell you that the used stimulus is not indicative of actual stimuli encountered in most music. They should repeat the process and keep the high SPL for a few ms instead of 90s to see what happens when one listens loudly to music. I'd wager that the higher frequencies that accompany the loud bass line, which are often loud by themselves are far more harmful, even if their total SPL is lower than the LF peaks.

A constant high SPL low frequency noise, like in a generator hall etc, is a far cry from what is discussed in any audio forum that revolves around music reproduction.
 

GaryH

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Well, to be honest, that's usually what happens if you go against the grain and present results/hypothesis that question well established facts/beliefs.

Is the position on here that high SPL (sub)bass frequencies won't cause hearing damage because our hearing threshold is high there a 'well established fact' though? (If so, established based on what evidence?) That audiologist does not seem to think so, in fact it's contradictory to their explanation and the physiological mechanisms of the cochlea, which are most definitely well established facts.
 

Aerith Gainsborough

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Is the position on here that high SPL (sub)bass frequencies won't cause hearing damage because our hearing threshold is high there a 'well established fact' though?
Only when it comes to music, as far as I understand it.

I don't think anyone here ever talked about noisy production environments and associated hearing hazards from !SUSTAINED! low frequency SPL, which is what your study worries about..
You are comparing Apples to Oranges.
 

GaryH

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Only when it comes to music, as far as I understand it.

I don't think anyone here ever talked about noisy production environments and associated hearing hazards from !SUSTAINED! low frequency SPL, which is what your study worries about..
You are comparing Apples to Oranges.

I'm not talking about the SOAE study there. I'm specifically talking about the inference stated as fact on here that high hearing thresholds at particular frequencies (sub-bass) correlate with low susceptibility to hearing damage from those frequencies. Where is the evidence for this? This does not seem to be an 'established fact'. Rather, it is inconsistent with known auditory mechanisms, and statements from a qualified audiologist.
 

Sean Olive

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To @Sean Olive, how does a speaker that measures flat in-room measure at the eardrum of a HATS with a standard artificial ear? I would love to see that curve.

The first slide shows a Revel F208 loudspeaker. Anechoic Measurements are on the left showing it is anechoically flat on on-axis.
When you measure its in-room response (shown on right) it produces the cyan curve which approximates the anechoic PIR response. When you equalize it to the preferred in-room target curve you are essentially adding bass below 200 Hz doing nothing else.

The 2nd slides shows the Revel F208 before and after it has been equalized to produce a flat in-room curve. We did this for some experiments where listeners could adjust the bass and treble of the loudspeaker as well as a headphone. They ended up moving the treble and bass back to levels that simulated the preferred in-room target curve. (ie they did not like a flat in-room target curve)

The 3rd slide shows response of the Revel F208 measured in the room using a manikin with a GRAS45AG coupler/pinna. The green curve shows the Revel equalized to flat, the black curve shows it equalize to the preferred in-room curve (the black curve in graph 1. This black curve is very close to the preferred headphone target response, which essentially mimics in headphones what people prefer from well-designed loudspeakers calibrated in a good listening room.
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ADU

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Thank you for the above post and explanation, Dr. Olive.

This may already be apparent to someone as well-versed in the design and measurement of speakers as yourself. But for those are not as well-versed... I think you'll find that the additional rise in the sub-bass in the above preferred in-room loudspeaker curve (or PIRL) is consistent with the predicted in-room responses of neutral loudspeakers with built-in subs that are somewhat better extended into the lower sub-bass frequencies than the Revel F208.

The predicted in-room responses of the Dutch & Dutch 8C, KEF Reference 5, Infinity Prelude MTS, Mesanovic RTM10, JBL M2, and Infinity Intermezzo 4.1t would all be fairly good examples of this imo...

https://pierreaubert.github.io/spinorama/Dutch Dutch 8C/ErinsAudioCorner/index_eac.html
https://pierreaubert.github.io/spinorama/KEF Reference 5/KEF/index_vendor.html
https://pierreaubert.github.io/spinorama/Infinity Prelude MTS/Infinity/index_vendor.html
https://pierreaubert.github.io/spinorama/Mesanovic RTM10/Mesanovic/index_vendor.html
https://pierreaubert.github.io/spinorama/JBL M2/JBL/index_vendor.html
https://pierreaubert.github.io/spinorama/Infinity Intermezzo 4.1t/Infinity/index_vendor.html

All of these speakers have a pretty flat direct/on-axis response (except for the Infinity Intermezzo 4.1t, which "cheats" the sub-bass up a bit in its direct response). And they all pretty closely approximate the additional rise in the sub-bass response in your PIRL curve in their in-room and sound power responses, due (imo) to their better extension into the lower frequencies than the Revel F208.

Although I don't have any graphical or measurement data to support this, I suspect you'd also get a similarly elevated in-room response in the sub-bass from a pair of smaller neutral speakers, paired with a good sub-woofer, or multiple subs. YMMV though on this.

This is the type of response that I assume the Harman curve was more or less intended to approximate though.
 
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ziddy76

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Seems like everyone has a home brew for eq( enhancing ) headphones SQ on this forum. As a science based forum , the directive to just listen to changes does not get me very far. Once someone creates EQ adjustment list isn’t there an objective way to measure the suggested SQ improvements? The actions of amateurs and enthusiasts and electronics designers based on personal preferences does not instill a lot of confidence for me to try their various recipes. Why don’t headphone makers provide various EQ scenarios for their products? Just curious…

Umm manufacturers do. Those wireless headphones got built in amps which definitely use a DSP of some sort to influence the sound. You can tell with some headphones that can be both wired and wireless, when wired they sound completely different.
 

Sean Olive

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Umm manufacturers do. Those wireless headphones got built in amps which definitely use a DSP of some sort to influence the sound. You can tell with some headphones that can be both wired and wireless, when wired they sound completely different.
absolutely. If the headphone is active and has a DSP chip any sound profile is possible.
 
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