Measurements: Charts, Graphs, Software & Methods



Nuraphone is weird, because when I first heard their pitch (“We stick a thing in your ear and measure to get better sound”), it made perfect sense to me: personalization of headphones to individual HRTF is almost certainly the future (Smyth’s Realizer being an extreme example), and so I figured that was what they were doing. Looking closer at how they say it works, however, apparently they use otoacoustic emissions as their major (sole?) test. I’m not an audiologist, so perhaps there’s some nuance I’m missing there, but my understanding was that otoacoustic emissions can be used to determine hearing damage, rather than HRTF. I guess compensating for hearing loss is a pretty useful feature in and of itself, but it’s not what I’d expect.



Thanks for the annotated exposition. I found it both useful and interesting. As I’m known for being entirely irreverent (and yes irrelevant too) on this forum, might I suggest that there may be a market - as there is in certain other products - for some celebrity ear models?

Imagine testing on a molded set of Beyonce’s ears. Or, for that matter Eric Clapton’s?

I’ll crawl back into my box now.



In a sense, our ear sims are already based on celebrities - albeit within this nerdy field - as Gunnar Rasmussen and Per Brüel’s ears were used to make the impedance target for the first IEC711 sim. Still, I think pinnae probably have more market appeal, particularly for the binaural folks - forget “as the artist intended”, now you can have “exactly as the sound entered the mastering engineer’s ear”!



Great post @Mad_Economist! I really appreciate the post, data you’ve accumulated, and citations.



I’ve been playing around with a Dayton IMM-6 and Audessey Calibration mics for IEMs using 2mm wall thickness vinyl tubing and REW.

I’ve been making some calibration curves for Diffuse Field and Harman Target IEM curves and here’s my current results:


Moondrop Kanas Pro

I used MiniDSP’s Diffuse Field calibration curve to normalize the Dayton data to Diffuse Field and then used ER4 data to normalize to Harman Target. Probably not exact in anyway, but it’s a start. I’ll probably be tweaking it a bit more when I have time.

Obviously, I made a lot of generalities of the Harman curve response.


I compensated incorrectly to ER4-XR instead of ER4-SR. I fixed that in latest photos.



How have you been volume matching measurements for comparing different IEMs using the Dayton mic? Up until now I’ve just been taking overall SPL measurements but Crinacle told me matching resonant peaks would be more accurate.
Another issue I’ve encountered is that the compensation file Crin gave me for the Dayton mic is intended to be used when the IEM is inserted into the coupler at a depth that creates a 9k resonance peak, but a lot of the IEMs I’ve gotten for review have a huge dip between 7-10k that seems to be by design.

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Yes I always volume match at 80dB SPL for my measurements at 300Hz – which can be around 90 or so at 1KHz depending on IEM. But I match at 300Hz because that’s what MiniDSP recommended and I’ve sort of stuck by that convention. As you know, volume can greatly change how the response is.

Yea I read his methodology and that actually isn’t a bad idea. My database unfortunately was already started at 300Hz but at a much lower dB that he tests at which I believe is mid 90s. At 80dB SPL @ 300Hz probably is around low to mid 90s for most IEMs around those areas anyway.

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I just started playing with a Dayton IMM-6 and FFT Plot and I’m having a lot of fun. The vinyl tubing is a lot easier to work with than the janky MiniDSP E.A.R.S. ear canal and I think the measurements look more like what I hear.

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Yea I do like the ease of use of the IMM-6. I prefer using it with my computer and REW over FFT, but FFT is still pretty nice to have for ease and portability. A head-fier from Austria has been trying to 3D Print some couplers to go with the IMM6 and he’ll start sharing his results with me when he gets satisfied.



I’m sure I will too, sadly my Macbook Air doesn’t seem to work with TRRS mics. I’ve got a $7 USB dongle on the way that should rectify this.

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Yea I use a TRSS splitter to separate mic and stereo channels, which go into a cheap $7 USB soundcard.

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Just got this IEC IEM coupler!





Whoa! Can’t wait to see all of your reviews. Please, please, please include the Harman Target overlay on all your measurements. I know a lot of the points by heart, but still, it is way easier for us lazy people to just see it graphed. Thank you!

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Yea, I’m excited for this. I’ve seen them on taobao (where Crinacle got his) but since I don’t read chinese, I had no idea what I was getting. They aren’t too expensive. I ended up picking up DIYearphones’ coupler when he decided to close up business last week. Made my life easy and came quick. Also came with an external USB Audio interface that pairs with the mic.

I used it on my Fearless S4 review I just posted. Really liking the results of the measurements now. :slight_smile: