BINAURAL MICROPHONE – DUMMY HEAD DIY V2
Advanced version and improved case strength of the Binaural Mic DUMMY Head.
Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3-D stereo sound sensation for the listener of actually being in the place where it was recorded.
This effect is often created using a technique known as “Dummy head recording“, wherein a mannequin head is outfitted with a microphone in each ear.
Binaural recording is intended for replay using headphones and will not translate properly over stereo speakers.
If you plan to use the Binaural Dummy head for measuring exactly how the human eardrum would receive sound, you need to use an ear canal, as your goal is to “measure” what is arriving to the eardrum.
Bur for playback of binaural audio recordings, which is the most typical situation, the capsules must be placed in the exact location where the headphone will be.
The reason for this is that, if the capsule is placed inside an ear canal, when you playback those sounds trough headphones, the sound will have to travel from the Speaker to your eardrum once more… causing “tube” effect and unwanted frequency response.
Silicone human ear models for Binaural Recording:
One of the hardest steps in the whole project was the Silicone Human ear models. Is not as easy as I thought at first to get proper “anatomically correct” model. I struggled nearly a month to find a source for proper silicone models trough my brother, which is a Biologist and he managed to guide me in the right direction to get my first pair.
They were expensive and I wanted to continue building new Binaural microphones, so the solution would be to “clone” this original molds. For this task I also got the help of my brother and father which are extreme DIY enthusiast. My brother loves Roll games, and started doing his own miniatures a long time ago, he started cloning this originals using a Custom made vacuum chamber which allows bubbles to disappear when making molds. Amazing stuff.
So with this components and a bit of messing around, we finally managed to get good results. We have made a first batch testing different consistencies, ways of coloring, trying different shapes for the base… The next test will be made using a slighty softer silicone but the final mold is done.
I will be providing trough the shop this Silicone human ear models for anyone interested.
Why is important an “anatomically correct” human ear model?
Function of the Pinna or Auricula:
The function of the pinna is to collect sound, and perform spectral transformations to incoming sounds which enable the process of vertical localization to take place.It collects sound by acting as a funnel, amplifying the sound and directing it to the auditory canal. While reflecting from the pinna, sound also goes through a filtering process, as well as frequency dependent amplitude modulation which adds directional information to the sound (see sound localization, vertical sound localization, head-related transfer function, pinna notch). The filtering effect of the human pinna preferentially selects sounds in the frequency range of human speech.
[QUOTE]”…The reason for this is that, if the capsule is placed inside an ear canal, when you playback those sounds trough headphones, the sound will have to travel from the Speaker to your eardrum once more…”
In theory, the more close the capsule is to the ear drum (as much as possible inside the ear canal) the more the sound will be “coded” by the ear before being captured by the capsule. So I assume that for an even better experience sounds should be recorded with the capsule inside the ear canal and listened with earphones rather than headphones. Do you agree with that?
Hi Paolo. If you intend to do Cailbration of Headphones, Home Theaters etc, then yes… Earcanal and Equalization is needed to acomplish propper measurements. My first experiments were all made using earcanal models… Recording White noise in a treated Room and applying EQ to critical areas like 3Khz and others due to the phisics of the artificial head.
My results using EQ were not really satisfying, attempting to make flat a response, considering the Capsules are not 100% flat, neither the room acoustics or Speakers used for reproducing the white noise…
You are right in saying that in theory the capsule should be as close to the eardrum as possible, but your earphone is never going to be totally inside your 3cm earcanal. An earphone will be position exactly at the pinna.
There is plenty of information online, research by many people doing Binaural recording for different purposes, is worth checking all the available information around. I personally made a lot of research, try and error, have built 5 Binaural dummy heads, allways improving the results.
100% perfect Binaural recording doesn´t compute since we are all different, even up and down localization is not a “Dummy Head” issue, but a limitation of our anatomy that gets enphasized in Binaural recording. Are you making a project? I´m happy to help if you need to. Just write me a pm.
All the best!
yes, I’m experimenting with binaural recording since 2007 and I have built so far 2 headset (designed specifically for my ears) which I wear to make my recordings. Of course, since I can only put the capsules at about half cm inside my ear canal, their position is more or less at the same position of the earphones so it all matches well and the results are quite good (although I haven’t experimented yet with other capsules positions so I cannot compare).
I am now building a third headset (and a 4th after this) because the one I’m currently use starts to be old and glitching. I have used panasonic wm-61a capsules so far and I am now looking to find something (not too expensive) with more s/n ratio and sensitivity but keeping the same (or almost) frequency response as the panasonics. I have seen the Primo EM172 which seem to be just what I’m looking for but their diameter is 10mm, a bit too large for my ear canal… I’m thinking of using them for my 4th headset, placing the capsules just outside the ear canal.
I have seen also the naiant x-x, which seem to be a good alternative, but at naiant said that their cable cannot bend at 180° from the capsule in order to put cable and capsule inside the ear canal…
Do you have an alternative with 6-8mm diameter to suggest?
Thanks for your support!
Hi Paolo, actually I didnt find any smaller capsules, the Primo ones seem the better choice for my setup. I find very interesintg your experiments and I understand your approach because you mainly use your own ear system and body to record and then experience the recording… Which is for sure the more realistic. In that case you are totally right, but your problem then is to find capsules small enough to insert them in your ear. Don´t you have issues with the cable? Will love to know more of your experiments and test some results! Cheers!