This DIY Audio Setup Simulates Human Hearing with a Pair of Microphones

The magic of binaural recording

Going from only a single channel of audio, also referred to as mono, to two channels, called stereo, was a major advancement in the realm of sounds recording. Now, listeners could experience similar positional effects as they would in real life, since humans use a pair of ears to hear, thus creating two internal channels of audio information. However, most recordings are still taken with only a single microphone, and for ones that use a pair of microphones, it still does not sound "correct". This mostly comes down to the relative positioning of the microphones and how sound is channeled towards them.

Binaural recordings attempt to simulate how humans pick up sounds by placing a set of two microphones on a mannequin head, which is called dummy head recording. This lets the audio naturally flow towards the microphones and recreate the stereo listening experience that a real human would perceive.

Issues with other devices

Although it might seem simple and easy to get started, most professional-grade equipment is commonly priced at several thousands of dollars, making it difficult for amateurs to try out the technique. Several years ago, audio and radio YouTuber Kevin Loughin began experimenting with binaural audio by placing a wearable microphone is each of his ears and then going for scenic hikes to capture a wide variety of details in nature. However, mobility issues and an inability to remain completely still for long stretches of time proved to be impossible, which is why he decided to create a cheap binaural recording project that could be mounted anywhere.

Selecting a suitable model

To start the project, Loughin's first task was to find a mannequin head that was both cheap and shaped/weighted correctly in order to simulate a real person's head. What he located was a wig display model that had plenty of dense foam on the inside, thus preventing echoes from reverberating across to the opposing microphone. Next, he designed a small 3D-printed box for housing the necessary electronic parts and prevent them from becoming damaged if the assembly topples over. The final step was cutting out a large rectangular slot in the back of the head for the box, along with a smaller cutout for a 9v battery and a smaller hole in each ear for the microphones to rest within.

Electronic components

Loughin decided to go with a pair of mini electret 10mm condenser microphone elements due to their small size and minimal need for external support circuitry. After soldering some wires to their terminals and passing them through the mannequin's head, he lastly attached two 4.7uF capacitor and a couple resistors to improve their sound quality. Signals from the elements then pass through a potentiometer to control their gain and exit out of a single 3.5mm jack to a recording device on the other end.

A few experiments

With his new binaural audio recording setup now completed, Loughin set up a few tests to determine just how realistic the sound profile was. As can be heard from his demonstration video on YouTube, the project lets anyone wearing headphones experience the sensation of a person walking in front of them as well as having a conversation with someone else to the side.