In the thick of it instead of just there: spatial sound recording with a smartphone
14.5.2020
Translation: machine translated
Why smartphones produce an astonishingly realistic sound and how you can improve it.
The audio quality of videos that I record with my smartphone has often surprised me in a positive way - especially in direct comparison with the recordings from a camera's internal microphone. However, I only recently realised why this is the case. It's the surround sound.
Recording sound in stereo creates a spatial impression. But that doesn't mean the sound is the same as what we hear in reality. It sounds different than if we were actually in the middle of the action. An ordinary stereo microphone is constructed differently to our ears. Here is an example of a clip-on microphone from the last millennium that I still use occasionally. Left and right are very close together.
The two microphones of a camera are also quite close to each other. They also look in the same direction, unlike human ears.
On my smartphone, the two microphones are on the short edges at the top and bottom and therefore about 14 cm apart. It's a Huawei P20 Lite, but that doesn't matter, most smartphones have the same design in this respect.
This 14 cm is pretty much exactly the distance between our ears.
Physical distancing between the microphones
Of course, this alone is not enough to make the recording sound as if you
were in the centre of the scene. in the middle of the scene. Ideally, there should be more than just air between your ears. If a sound comes from the left, you can hear it with your right ear, but some of the sound waves are blocked by your head.
I can semi-separate the two microphones spatially by cutting a gap in a piece of cardboard. Of course, this is tinkering at the lowest level and only a very rough approximation of the conditions of our ears, but even with this you can already hear a clear difference, as the test video below shows.
First you hear a recording with the camera pictured above, the Sony RX100 III. Although this is stereo, it sounds like it's coming out of a box. The recording with the smartphone sounds much more open. Finally, a recording with the cardboard box. Pay attention to the moment when I turn 90 degrees. Here you can hear much more clearly that the music is now coming from a different direction than in the recording without the box.
Build a binaural microphone yourself
In a real binaural recording, a human head is modelled. The microphones are inserted into artificial auricles. Thomas Kunz, the photographer from Digitec Galaxus AG, is currently in the process of building such a microphone. As soon as he's finished, we'll show you the result and how we got there. <p
David Lee
Senior Editor
David.Lee@digitecgalaxus.chMy interest in IT and writing landed me in tech journalism early on (2000). I want to know how we can use technology without being used. Outside of the office, I’m a keen musician who makes up for lacking talent with excessive enthusiasm.
