The essence of binaural stereo sound recording is being able to capture the experience of human hearing by reproducing the live sound exactly as it was recorded!
When different sound wave frequencies enter the left and right ears, they cause our brain to resonate with them; hence creating the powerful tingling sensation called ASMR (Autonomous sensory meridian response).
The better quality binaural microphone you have, the better you will be able to capture and reproduce the binaural effect over headphones or over regular stereo loudspeakers.
If you are someone looking to do quiet field recording or ASMR role-play videos on YouTube, you will want a binaural microphone such as the 3Dio that has a low self-noise (14 decibels) for recording at very low sounds.
With a low self-noise microphone you will be able to reduce significantly the hissing sound produced by the microphone when it is recording.
The 3Dio model I am reviewing is the Free Space binaural microphone, which has an Omnidirectional pattern and a frequency response that ranges from 100 Hz to 10kHz. The 3Dio Free Space frequency range is great for recording percussion or stringed instruments like drum cymbals or acoustic guitars.
 The 3Dio Free Space binaural microphone has a distinctive unique design with soft silicone ears that mimic the distinctive soft texture of human ears. Inside the silicone ears, you will find Primo EM172 microphone capsules inserted in each ear. As the mics are inserted inside the ears you can take the 3Dio outdoors without having to worry about wind noise.
The Primo EM172 microphone capsules are powered by a single 9V alkaline battery located inside the chassis of the 3Dio.

The 3Dio Free Space features a standard stereo 1/8" (3.5mm) jack socket and comes with a 3.5mm male to male cable that allows you to connect the 3Dio Free Space binaural microphone in to a stereo audio recorder, camcorder or microphone pre-amp.
The Free Space also comes standard with a 1/4" (6.5mm) female thread mounting hole in the bottom of the hot-shoe adapter, so you can mount the 3Dio directly onto a tripod or microphone stand (if using a mic stand adapter). Below you can see the 3Dio attached to the Joby Gorillapod flexible tripod and the 3Dio attached to the VEO 235AB tripod

If you are looking for a portable binaural microphone solution, the 3Dio Free Space binaural microphone is perfect to take with you on the go. It only weighs 680 grams and measures 19cm wide by 11cm high by 11cm deep.