Discrepancies in sub bass of graphs vs perception in iems

[pier25]

I’ve purchased a couple of iems recently like the Crinear Daybreak and the Thieaudio Hype 4 mk2 which I perceive having massive deep rumble compared to what I see on the graphs. Basically they sound like someone put a subwoofer into my ear. Tip rolling doesn’t affect this. It's not a seal issue either.

The weird thing is, some iems I own like the Truthear Pure or the Chu 2 sound fine to me in terms of low end quantity and they don't graph that far off. But eg the Crinear Daybreak or the Thieaudio Hype 4 mk2 are unlistenable to me.

Anyone has any idea what might be going on?

I’ve never experienced this with headphones. Typically what I see in the graphs aligns somewhat with what I hear.

Eg here's the Moondrop Chu 2 vs the Daybreak:

I've attached some 5128 measurements from Crinacle's database and from the Super Review 711 database.

 

[jmdesignz2]

bone conduction-like effects?

 

[pier25]

bone conduction-like effects?

Maybe there's some of that... but after discussions on another forum and chatting with LLMs I think it's probably more related to acoustic impedance and the pneumatic effect.

Basically the Daybreak and the Hype 4 mk2 produce a pressure build-up which I perceive as a massive low end boost.

This video explains the concept:

 

[sq225917]

I find vented iem shells sound better. Someone should do a set of iem with a release valve on them, that ports ear canal pressure from insertion. Like a helium release valve on a divers watch.

 

[Redacted]

Measurements are based on a standard ear rig.
If your is not internally shaped like the 'standard ear', and headphones may sound wildly different to expectation.
Mr Chepo says buy several IEMs for under $50 each. You will likely find one set that will work great in your ears. And spend some effort finding the right-sized silicone bud to seal your own ears.

 

[JanL]

Individual sensitivity to occlusion effect, most likely. Personally I'm not bothered with bassy IEMs, but I can easily tell the difference between my 64Audio Nio with the vented Apex module and a typical IEM that's well sealed. The Nio sounds and feels like open back headphone even though the bass level is very comparable.
On another note, I prefer the original Hype4 over the MK2 because it has more impactful bass. I bet you would hate it even more.

 

[pier25]

Individual sensitivity to occlusion effect, most likely. Personally I'm not bothered with bassy IEMs, but I can easily tell the difference between my 64Audio Nio with the vented Apex module and a typical IEM that's well sealed. The Nio sounds and feels like open back headphone even though the bass level is very comparable.
On another note, I prefer the original Hype4 over the MK2 because it has more impactful bass. I bet you would hate it even more.

It's not the occlusion effect, it's about acoustic impedance.

I don't hate bass

 

[JanL]

It's not the occlusion effect, it's about acoustic impedance.

I don't hate bass

Acoustic impedance, as in your ear canal and ear drum are stiffer (or maybe looser) than mine? How does that work? I saw the graphs of measurements of acoustic impedance of ear canals and the acoustic impedance is highest at the lowest frequency and gently fall down with increasing frequency. In the middle and treble there a few resonant spikes related to the length modes and tympanic membrane compliance.

The problem is that responses across many people are similar in the low frequencies, but vary more in the mid and high frequencies. Graph below from this paper: https://ar5iv.labs.arxiv.org/html/1811.03848

 

[pier25]

Acoustic impedance, as in your ear canal and ear drum are stiffer (or maybe looser) than mine? How does that work?

I'm no expert but my understanding is that it's related to the volume of air pushed by the driver(s) and the volume in the ear canal.

I honestly have no idea what's going on but this seems to be the only explanation as to why some IEMs I've tried have a massive boost in the lower frequencies.

If you look at 5128 measurements I shared in my first post the Chu 2, Daybreak, Pure, and Hype 4 have similar deep low end levels but that's not at all what I hear.

The problem is that responses across many people are similar in the low frequencies, but vary more in the mid and high frequencies.

AFAIK those changes in high frequencies are related to resonances due to ear canal length?