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jonny

Binaural Microphone

by jonny Oct 13, 2014
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Cool design! Is the bottom nut meant to used when mounting on a tripod? Or is the screw so posed to go into both nuts?

Thanks, the bottom but was meant for a tripod, the screw only needs to go into the top nut.

hmm, experts say, that is suboptimal.
Like this "3dio free space" microphone.
There are people, they say they can hear a dummy head with and without shoulder...
Look: https://translate.google.com/translate?sl=de&tl=en&js=y&prev=_t&hl=de&ie=UTF-8&u=http%3A%2F%2Fwww.tonthemen.de%2Fviewtopic.php%3Ft%3D2237&edit-text=&act=url

My whish (next project :-) ) a realistic human head.
With a massive skull, fillable (wax, plasticine etc.) skin/flesh with cavity structure, hollow for the "brain"...
Perhaps also 9lbs, weight of a human/male head...
And optional: Shoulders

Hi! Thanks for this it's Awesome! I've ordered two Lav mic from Amazon can't wait to test it out.

I'd like to know if, once wiring is all done, if Windows will see the Stereo sound right away in any recording software or I gotta use a special recording devide with Stereo mic capability?

If I printed with flex filament but at 35%, do you think that will have a negative effect?

No, ears and the sides should be flexible if using a very flexible filament 35% or more is good, I've used TPU before and if at a low infill can be really soft.

Hi jonny, do you have any recordings?

I actually don't it was for my dad, so I haven't used it. Sorry. They should turn out fairly good if used with decent microphones and if a styrofoam head surrounded it even better.

'Sorry, there was a slight ommision:

In 1. I meant to refer to cutting apart a styrofoam head, such as you can find at "Hobby Lobby".

'My appologies.

Honestly, I think your creation is rather intriguing, and nowhere near as bad as "frogbutter" wants to allude. Whereas ALL the so-called issues CAN be addressed.

  1. The "head-shadow" can be addressed by cutting open, (and a slight amount of hollowing to adjust nearly exactly for your unit), your unit installed and the head glued back together with a compatable adhesive.
  2. This assumption is actually wrong all together! Both ear canals in fact do join together, and combine with the sinuses. If anything, it could be argued that your design is faulty for not including the sinuses, NOT because the ear canals are connected. BUT, I feel that that's REALLY getting carried away with things.
  3. Actually, the tympanic membrane would be located approximately 1 inch in from the opening of the ear structure. Therefore, that's where the microphone placement should be optimal.
  4. Shock mounts are NOT needed, remember the actual ear canal is a boney structure, with a VERY thin layer of flesh lining it, (this flesh is just barely as thin as a dime). So really, that thin flesh does little, to nothing to affect the sound quallity. Well, maybe. But, you would need to be a highly skilled audio technician to hear the difference. If you were truely fanatic about it, the artificial ear canal could be given a thin silicone lining, but in my honest opinion it isn't needed.
  5. Finally, yes, the external ear structures [COULD] be cast in silicone. He would simply need to separate the external ear section from the rest of the model, and print that. Once the outer ears are printed, he would need to make a flexible mold of the outer ears, (personally, I would recommend a suitable urethane, but be carefull, not all urethanes are friendly to silicone). Then, he could cast the ears with a minimum of molding and casting. Once the outer ears are finished being cast, they can be glued onto the model with the appropriate type glue. But, with this all said and done, flexible silicone ears are NOT going to add anything to the audio resonance in any noticable way. If anything, it [MIGHT] make the overall unit somewhat structurally more ruggid. Whereas, the outer ear will not be able to chip, or break off, they will simply flex.

Now, IF you truely felt you NEEDED to make these modifications, they can be done. And, done relatively easily. But, I really don't think anybody needs to go to those extremes. So, "jonny" I personally think you did a damn fine job, and should be commended for your efforts. So, GREAT JOB!!!

Wow, thank you, both you and froggbutter took this way farther than i though anyone would. For anyone who makes this the styrofoam head idea is great because I think it should work well and is very cheap at hobby lobby there is 3 different kinds ranging from $5-$8.

Hi Jonathan,
Thanks for this awesome model, I have made a derivation ( https://github.com/carlosgs/OpenBinaural ) that incorporates the ear canal & some "head isolation".
Normally I don't use Thingiverse given Makerbot's policies (Takerbot), but felt the need to let you know.
Thanks again, I hope you are keeping up the good work!

You're welcome, I'm glad you like it and nice job on the model.

Please don't take this as negative feedback because this is an awesome start, but for true binaural recording I would make the following recommendations:

  1. There should be a head because part of binaural recording is accounting for the "head shadow", otherwise this is just regular stereo.
  2. There should be complete separation between the two sides, otherwise the audio from one side will transfer through to the other.
  3. The microphones should be set just barely inside the ear canal.
  4. The design should have shock mounts to reduce transmission through the structure.
  5. The ears should be either molded in silicone or printed with something like Filaflex. PLA or ABS will transmit/reflect sound more like bone than skin and cartilage.

Hi !
For the first point, do you mean a head like the skin part around the ears or something else ?

Like an actual head. This helps to account for the way that sound waves travel from their origin relative to the ears. For instance, sound that is directly adjacent from the left ear will not sound the same coming into the right ear due in part to the reflective/absorptive properties of the head. Granted a fake head won't be exactly the same, but it will at least cast approximately the same shadow. Super high-end binaural recording setups actually have heads with the same density and audio reflection values as human heads. Basic setups are often not much more than a foam wig head with holes drilled in the ears.

As Jonny brought up below, this may be restrictive for many people to 3D print without carving up a head model and printing it in sections, so my recommendation would be to print this model (because let's be honest it's pretty great), and then buy a foam head from Amazon ($2-$12 depending on gender and/or seller) and carving out the inside a bit.

Thanks for the answer.
I've seen a foam head on Youtube and this model from Shepshepard in the comment section... This model sound REALLY great at my ears (better than the foam one).
But I also see a professional model that look like this one but with a circle around the ear (and wind protection that also make it look less weird...)
I think i will print this thing, with a camera adapter. But... let's push the exercice. If YOU have to make a binaural microphone, will you put printed ears in a foam head (or mannequin head), or the complete device in a foam head ? With the central cube and the -empty- tubes, I don't understand how a light foamy head could help (but it make more sense to me with a heavy head).
And after all, this fake-head will make what ? The "hummmmming internal sound" that will make my voice sound more like I hear it and not like my computer reproduce it ?
More... I don't hear a sound like you do... neither my baby or my dog, as we all have different ears and distance between them. Plus the fact that we don't have the same microphones or headphones. But the binaural concept is about the sound itself or about the spatialisation of it ?
(to be honest, I love to say to people with 7.1 sound systems that we have only to ears, and that a 2.1 sound system is easier to configure and work better)

(There may be a translation limitation for me... I hope you will understand what i mean).
(plus it's a really interesting discussion, thanks)

I think I understand what you're asking, so I will try to answer each section of your question individually.

  1. If I had to make a binaural microphone and I didn't have time to completely reengineer it (let's say I only have 24 hours), I would absolutely print out the whole model and with limited modifications mount it into a foam head. Honestly even if I did have time to reengineer it, I probably still wouldn't because it really is a good start.
    My short list of minor modifications would be:
    A. Print the ear sections in flexible fillament.
    B. Move the microphones out to be just inside the ear canals. This is contrary to some other opinions that are posted here and I could go into a great amount of detail about the physics of sound, but it boils down to "that's just what I would do".
    C. Close off the center box from the ear canal to minimise the direct sound transfer.

     I would then get a foam head, cut it in half the long way, drill holes the diameter of the ear canal sections all the way through (carving out where necessary for the other parts to fit, push the ears through and then rejoin the two halves with tape.  
  2. The purposes of the fake head are to place the two microphones in a position that mostly closely matches the position of a person's own ears and to provide enough of a barrier between the two microphones to simulate the way each ear captures the audio sources differently.

  3. A fake head will not simulate what your own voice sounds like because the major reason you hear your own voice differently is because a large percentage of that sound is traveling through the bone and fluids in your own head. It will however simulate what it would sound like if a person was standing in the room with you and talking to you.

  4. Surround Sound (5.1, 7.1, 22.2, etc) is only semi-related to binaural as they're an attempt to reproduce the environmental audio as a whole and binaural audio is an attempt to replicate your position in the environment, which is why true binaural audio is usually listened through headphones (which goes back to why I would move the microphones).

Thank you again
I will print the ears in flex and will test with and without isolate the cube. And place the microphones inside the tubes. I hope I can make multiple test... Then we will hear if the differences are significantly.
It will take some time...

Well when making this I didn't it expect it too be as good as professional ones so I'm not surprised that there is several errors. Unfortunately some things people won't be able to fix like a head would be too big for most people's printers and not everyone can print in a flexible material. It would be cool if you could make some fixes and see how well it does.

I finally did a test with mine. even without a head it worked pretty well.

https://www.youtube.com/watch?v=0SBl5bnDX8Q&feature=youtu.be

How did you record it? did you just plug both 3.5 jack mic's in a splitter and in your camera or?

Sounds good, if you don't mind could I put your link in the description?

Go for it! Just credit me if possible

How far into the side_parts should the microphones be inserted? Should they be all the way up so they're almost sticking out of the ear, or should they be way down near the main_body ?

To be honest I don't know I think father down because your ear drum is far down but if I were you I would experiment.

Actually they should be set just barely inside the ear otherwise the sound will not be an accurate recording because it will essentially be passing through two sets of ear canals, one for the microphones and another for your own ears during playback.

Cool idea! Guess the sound would be even more faithful if I scanned my own ears and printed them out!

That should be true I think the material would have a bigger impact on performance than custom ears though. Which you could print these in a flexible material so it is more like flesh.