Stereo headset with binaural sound

In this article we will talk about a new, promising, in my opinion, device or gadget, capable of providing high-quality recording of binaural sound, including its playback and live broadcast from the external environment, with small dimensions.

A little background on how this model came into being.

While working on creating enveloping active headphones, I identified two critical factors:

  1. Identity of replica ears with natural ones. This includes precise geometry, reflectivity and sound transmission.

  2. The ability of the electronic component to transmit/record sound with high precision

Actually, the first models of headphones were made from silicone ears purchased from Ali, reduced in size and ready-made electronic modules of Chinese quality. Of course there was an effect, but it left much to be desired. Therefore, as for the electronic component, I decided not to suffer, but to take a ready-made solution in the form of a stereo recorder from the company Zoom. For microphones I chose WM-61 capsules from Panasonic, but later replaced them with PUI Audio AOM-5024L-HD-R in favor of higher sensitivity and low internal noise. The results could not but rejoice, the sound position was heard very clearly and the plan to create active headphones was exceeded. And then the thought came to me about creating a device for binaural sound recording.

The first experiments with recording music showed the shortcomings of the “ears”. They were expressed in clearly audible resonances on a high note. My test audio track was the song Fade to black by Metallica. The opening guitar part began to rattle treacherously, no matter what I did. As a result, after some thought, I decided to get rid of the smooth surface of the silicone ears, including making identical geometry.

Attempts to make a 3D model using a scanner were unsuccessful. The complex topography of the shells with all its depressions turned out to be inaccessible for conventional scanning. As a result, I decided to make impressions using alginate. Perhaps I will write a separate article about this technology at home.

The results were very positive at low cost. The material used was a silicone composite on tin with a hardness of 40 Shore A. The mixture, previously whisked until small bubbles appeared, was poured into the molds. So I tried to roughen the surface to get rid of resonances.

replica of the right ear made of silicone

replica of the right ear made of silicone

prototype street tests

prototype street tests

The new ears gave a much more realistic sound compared to the Chinese ear piercings. Sometimes it felt like you weren't wearing anything. But the HF resonances have not gone away. In the end, I solved the problem with a small tuft of fur in the microphone area.

The model turned out to be very successful both as a microphone for sound recording and for active headphones. But here are its dimensions… Being like a Cheburashka among people is probably not going to appeal to everyone. And from that moment I began to think about how to reduce the shape so that the effectiveness remained the same and the person was comfortable.

The task was not easy; reducing the ear model only led to worsening. And again Mr. chance helped. Koda arrived at the laboratory RAA to test the next prototype, I saw Roman Kuznetsov (founder of RAA) have microphones in the form of earplugs, which he (I think the first person in the world who had guessed this before) used to measure the acoustic properties of headphones. The solution is so simple and effective, I would even say brilliant. The stereo base, the shape of the head and ears, reflection and sound permeability, everything exactly matches the person to transmit full-fledged binaural sound.

But, a microphone is a microphone, and for a headset you also need an emitter with a full range, a flat frequency response and, importantly, an accurate phase response, and everything must fit in a tiny ear canal.

After much searching and experimentation, such an emitter was found. This is a model of a wonderful company Knowles SR-32453-000. A miniature speaker with a balanced armature, 6 mm in diameter and 4 mm thick, fits perfectly into the case along with the microphone.

emitters Knowles SR-32453-000

emitters Knowles SR-32453-000

I planned to use silicone on platinum as the material for the case, but due to the technological complexity of making it at home, I had to settle on plastic. In general, I worked on the form for quite a long time. After all, we needed a universal one so that it would be comfortable and hold up well. As a result, of all the options, I chose an elliptical profile with a slope and a depth of 12 mm.

headset body

headset body

headset body

headset body

stereo headset with recorder Zoom F1

stereo headset with recorder Zoom F1

I chose the company's recorder as a sound processing device Zoom. The connection diagram is unbalanced, with a separate external screen.

Of course, for professional sound recording you need a recorder with a balanced microphone connection and the ability to record with a high dynamic range, and there are such on the market, the same Zoom F3. Here, as they say, there was enough money for that. But there is still more to come.

At this moment contentThere is very little demonstrating the operation of the headset, but this is just the beginning. I will gradually fill it up as much as possible.

In general, the model turned out to be successful and coped with the main task. This is playback/recording as well as broadcasting of binaural sound with high accuracy in small dimensions. The model was patented, another small contribution to Russian innovative development in the field of sound. And I am confident that it will be in great demand among both enthusiasts and professionals.

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