Measurements: Charts, Graphs, Software & Methods

[Mad_Economist]

Thanks!

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.

[pennstac]

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.

[Mad_Economist]

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”!

[antdroid]

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

[antdroid]

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:

BGVP DMG

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.

UPDATED GRAPHS

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

[darmanastartes]

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.

[antdroid]

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.

[pwjazz]

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.

[antdroid]

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.

[pwjazz]

@antdroid

I prefer using it with my computer and REW

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.

[antdroid]

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

[antdroid]

Just got this IEC IEM coupler!

[antdroid]

[MCM]

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!

[antdroid]

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.

[SenyorC]

As my love for (and collection of) headphones and earphones is starting to continuously grow, added to the fact that I don’t spend as much time in the studio since I have a 5 month old baby, I am starting to think about doing reviews again and including headphones into the mix.

The fact is that I get a bunch of stuff coming through my office (currently I have 4 sets of Genelecs, 10 or 12 QSC amplifiers, various Mackie monitors, various Meyer Sound rigs, tons of different screens and broadcasting gear etc) so the reviews wouldn’t be exclusively headphones but I would like to be able to make some measurements for the few that I do review.

Please understand that these measurements are not intended to be industry standard, far from it, they are more of a visual reference between different sets that may come through my hands, most of these seem to be budget IEMs at the moment.

Anywhoo, my original plan was to set up a simple rig with the IMM-6, which I have had for years for using in rooms for quick reference, but after many years of use I broke it today as I was starting to put the DIY rig together. Rather than just getting another IMM-6, I thought I would pick up a set of EARS that are basically an all in one package that is plug and play.

However, after reading many opinions (good and bad) I had sort of moved away from the EARS set up and was looking more to spending that on a calibrated mic and making my own rig. Then, after reading this thread, I am again confused!!

Just as an FYI, I have various interfaces and mics (studio, not measurement) but they are part of the studio I share and I don’t think I will make the effort to actually go there and do any work. At home I have a UMC204HD interface, a couple of DSPs (BSS) and random other stuff I have collected over the years but I don’t have a mic here. I don’t mind DIY but I don’t have a huge amount of time to invest in the building (or rather, I don’t want to invest weeks of work building it!).

So, for the same budget as the EARS (200€ approx) would you say that they are the best option or would you go the DIY route?

[antdroid]

Hi,

EARS is a decent tool to use for the home hobbyist, and it works pretty well in my opinion for over-ears with the HEQ compensation they supply. In fact, i think the DF compensation they supply is pretty decent for IEMs. It’s just people in IEM world like Harman Target more, which they don’t provide. The over-ear headphone curve is based on Harman Target.

For IEMs, I have and still use EARs, as well as an IMM-6 cheapo setup, and currently use a generic chinese-made IEC711 coupler (which is a stainless steel tube+chamber+mic). It is the best for me, as the diameter of the coupler is the right shape and size for IEMs and results seem more consistent than EARS. EARS is not as consistent for IEMs and the shorter insertion depth and smaller diameter hole makes it harder to get good fit.

I recommend checking out this Head-Fi thread and take a brief read-through the first post and make sure you click all the “Spoiler” sub parts as csglinux has A LOT of very good info in it, plus links to buy various coupler options:

Audio Measurements on a Headfi Budget

[prfallon69]

Thank you very much for all the information Anthony. The link was great too. I wouldn’t mind trying out the EARS Measurement rig for myself with the hope of getting a better understanding of my Iem’s and headphones. This would hopefully help me with regards better Eq. I know @pwjazz uses measurements along with his extensive work on Eq.

[SenyorC]

Thank you @antdroid, that certainly was a productive read (as has been this whole thread).

So, the conclusion it has sort of lead me to is that I would be better off with a mic and coupler system than the EARS. That would also allow me to use the mic for FR curves of speakers etc (obviously using the correct room circumstances to do so). An issue I see is that I can’t find one of the couplers anywhere except for Tobao and I have no idea how to use that site

According to the thread linked also, the issue with the EARS seems to be the microphone itself (as well as the issue of getting IEMs to seat correctly as you mentioned). In which case, I guess they wouldn’t be appropriate for over/on ear headphone measurements either.

I guess I just want everything!!

[SenyorC]

I have just spent most of the day reading about measurement rigs, which then led to compensations, which then led to theories about ear canals, which then lead to audiology studies and papers, which then…

I believe that I am back at the beginning and will pick up a set of EARS and start from there!!

I was reading a few threads over on SBAF about compensation for the EARS, would you recommend using those @antdroid or starting somewhere else (with those supplied by miniDSP for example)?

Again, I am not bothered about them matching other measurements by other people 100%, although I would like to have something that is consistent for myself to carry on using and not change set ups in the near future. For example, right now I could measure the DT1990, the HD6xx and the Sundara to start having a reference point.