Homebrew Binaural Microphone Lets You Listen Like A Human

We humans may not have superpowers, but the sensor suite we have is still pretty impressive. We have binocular vision that autofocuses and can detect a single photon, skin studded with sensors for touch, heat, and pain, and a sense of smell that can detect chemicals down to the parts per trillion range. Our sense of hearing is pretty powerful, too, allowing us to not only hear sounds over a 140 dB range, but also to locate its source with a fair degree of precision, thanks to the pair of ears on our heads.

Recreating that binaural audio capture ability is the idea behind this homebrew 3D microphone. Commercially available dummy head microphones are firmly out of the price range of [LeoMakes] and most mortals, so his was built on a budget from a foam mannequin head and precast silicone rubber ears, which you can buy off the shelf, because of course you can.

Attached to the sides of the foam head once it got the [Van Gogh] treatment, the ears funnel sound to tiny electret cartridge microphones. [Leo] learned the hard way that these little capsule mics can’t use the 48-volt phantom power that’s traditionally pumped up the cable to studio microphones; he fixed that problem with a resistor in parallel with the mic leads. A filtering capacitor, an RC network between the cold line and ground on the balanced audio line, and a shield cleverly fashioned from desoldering braid took care of the RF noise problem.

The video after the break shows the build and test results, which are pretty convincing with headphones on. If you want to build your own but need to learn more about balanced audio and phantom power, we’ve got a short primer on the topic that might help.

21 thoughts on “Homebrew Binaural Microphone Lets You Listen Like A Human

  1. Just excellent. Well produced and presented. I really wish there were more videos on YouTubr like this. You have researched the subject well and treated your viewer with respect. More power to you. Thanks.

  2. Binaural recording is one of my favourite topics.

    Yes the creation of a synthetic head, with ‘ears’ and mics inside an ear canal, is one approach. It, um, looks funny in the field, though. Another, slightly less creepy rig is the Crown SASS binaural mic. You can also approach binaural with 2 spaced omnis and a Jecklin disc (Google away, folks)

    My favourite rig is also the easiest to make and use: get some Walkman-style open headphones, take out the lil speakers, and put in some small electret omni capsules, connected to the same wires. Done. These can immediately be plugged into any camera or recorder with plug-in power (found on cassette, MiniDisc, DAT and solid-state recorders, and many DV cameras). Or you can plug into an XLR adaptor which converts phantom power to electret-sized voltage.

    Besides being cheap and easy to make, these use any available head (including your own). They’re less conspicuous in public, and great for stealth recording.

    Try the following: put these recording headphones on and make a recording as you walk down the street, or a path, etc. Now, get some actual headphones, and play the recording while walking down the same route. It’s uncanny how real the sounds are; it’s hard to tell whether something you’re hearing is real or recorded til you look.

    1. “You can also approach binaural with 2 spaced omnis and a Jecklin disc (Google away, folks)”

      Now I kinda want a mic rig with the kitschyist chintzyist couch cushion between them.

  3. I have a pair of Soundman microphones. you put them in your ear like iPod plugs and they come with a separate preamp. I have the classical OKM II studio variant. very sensitive and a neutral sound, but they sell also versions you can use during a heavy metal concert and still sound perfect. no distortion.

  4. A ‘body’, here the head, is unnecessary, this sounds terrible. For our own hearing, our brains take care of that or else we would hear ourselves trough the acoustics of our head, something line a dull ‘woo-woo’, and we also would go mad.
    The most important is the direction of the mics, together with perfect replicas of auricles.

    1. Hmmm. That’s the exact opposite of how the Neumann mic is built. Minimal features in the ears, IRIC omnidirectional mic capsules, and the presence of a head. They actually sound pretty good. Sound takes time to propagate around our heads. That’s one of the ways the brain figures out the direction sound is coming from. If you eliminate the head, you eliminate the delay. That’s going to change the way the brain interprets location of sounds in a recording. Where does your information come from?

      I’m not sure that using a light weight foam head is going to replicate the acoustical properties of our own very dense head- it might be better to use molded plaster or maybe a thin shell filled with ballistic gel.

        1. Hey all, Leo from LeoMakes here. Mrehorst is right–the “head” is important because it helps you localize sound in two ways: 1) it creates an acoustic shadow for high frequencies (it blocks high frequencies) and 2) it forces low frequency wavefronts to wrap around your head before they get into the second ear instead of going straight through. Taking the longer path around means there’s a phase shift between the ears hearing the same sound and the brain is *really* sensitive to phase relationships. Between differences in loudness, time-of-arrival and phase, the brain can pretty reliably localize sound. If you take all that and add the ear lobe on top (the lobe is basically an acoustical filter that changes depending on the angle of the sound source to the head), well, now you can pinpoint the sound. But all this happens in your brain, which I think is amazing.

          BTW, I actually did look at ballistics gel to see if I can make a Mythbusters style dummy head with exactly the right density of a human head. Unfortunately, ballistics jel is really expensive and kind of hard to work with (I don’t know how to do casts and molds) so I just went with a dummy head instead.

          @emma: Ear-resistable! Very punny!

  5. Decades ago, Stereo Review had an article about bi-aural recording, one point of view stated that a mannequin head with exaggerated features (large nose, ears, eyebrows) made the recordings more lifelike.

  6. I made a binaural mic that just fit on my own “dummy” head years ago and made some recordings with it while I was living in Japan and Missouri. At the time I was recording on Minidisc (remember those?).

    My old recordings are posted here: https://drmrehorst.blogspot.com/2018/10/binaural-recordings.html

    In the ensuing years I have acquired a Sony PCM-M10 recorder and much lower noise mic capsules (Primo EM-172). I haven’t made many recordings with it yet, but it’s on my to-do list “one of these days”. The lower noise mic capsules provide a much quieter background for the recordings- not too important when recording loud things, but very important when recording quiet stuff.

    1. so cool. Thanks for posting. I have some recordings (binaural to pro Walkman) from a visit to Japan in the mid-90’s but can’t find the cassette. Also some recordings from around Europe on MD (2007).

      Do I remember MiniDisc? There’s a MZ-R50 (bought new in ’99) and a MZ-R90 (ebay) on my desk. And somewhere in the basement a component MD deck modified for SPDIF out. :-)

    1. yep.

      I have been mainly using the Panasonics (or copies), and they are remarkably good for like $1 apiece, and ideal for loud concerts… but I sprang for two matched pairs of Primo EM-172s last fall, and finally packaged a pair up last month… and they are indeed very very good for recording quiet stuff.

  7. I have been doing this since the 80’s with a wig stand and an AKG head I was gifted with. It had the original down a curved path to 2 old school dynamic mics. It got the electret mics set right at the surface of the “entrance” of the ear canal. Binaural experts suggest that the path stop and get mic’ed and get reproduced from the same point. So surface of the ear seems best? Easiest for sure. I have many area GD jam bands, blues, and other live music in this format on cassettes that need to be digitized.

    The movie Brainstorm where Natale Wood died both in script and for real was a good example of what my binaural tapes of shows back then got in responses from people I demoed the show tape to. It knocks your socks off! So the Halloween after the movie came out I dressed up as a scientist from the lab in the movie. White lab coat and over the shoulder cassette recorder and mics that clipped on the beck end of my glasses and projected down a wire to sit as near as possible in by ears, and other props. I started recording a block away from the near campus hippie bar and wandered up and in and through the 2 sides of a tape and captured the whole scene. A little cosplay ensued as I talk with friends whom I’ve long forgotten.

    I only did a little with video and binaural with a stereo VHS camera but would consider it necessary for any live digital video with good audio in 2 channels. Spaced at zero distance pairs of mics that try to be directional just don’t have the same effect.

  8. Hey folks. Leo from LeoMakes here.

    Firstly, thanks very much for watching and your lively discussion!

    Secondly, there are a lot of smart people here so maybe this is a good place to ask the question: Have any of you used with MEMS style microphones in a music or recording context? Did it sound good? I know mems mics are used in cell phones and smart speakers and whatnot for voice, but I’m wondering if anyone has used it for more “hifi” purposes.

    Curious to hear your thoughts.

  9. Awesome. Despite (because?) being alone in a room with headphones on, at 7’00 a guy just behind me on the right side made me turn my head … to see… an empty room. You got me there! Awesome!

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