Stereophonic sound recording was first known as a binaural sound—and it all started with a talkie at a local cinema. A talkie was an early sound film that used a single speaker. When Alan Blumlein first discovered this device, he realized there was a way to follow the actors across the screen. This was the first description of a stereo sound! However, nowadays we associate the term with the real binaural sound effect.
Binaural Sound: the Technique
Binaural recording is a technique that involves two microphones. The disposition of these microphones creates a 3D sound that resembles the experience of a person that is in the same room.
You can achieve a binaural sound by using a technique known as dummy head recording. In order to mimic how our ears receive sound, you outfit each ear of a mannequin head with a single mic. (Although it’s worth mentioning that some people use a simple separating component between the microphones instead of a mannequin head.) With this technique, you understand the small deviations known as HRTF’s. You comprehend how sound bounces off the head, how it gets into the ear canal, and finally reaches one ear and then the other.
Headphones: Essential for Binaural Sound
After the sound has been recorded in this way, the binaural sound can be replicated using headphones. It’s essential to have a separation, so mono playback and stereo speakers are not optimal. The reason is that the arrangement’s unique acoustics distort the channel separation through natural crosstalk. Thus, headphones are ideal, since sound cancellation equipment is very expensive.
Timbral Coloration
Timbral coloration is an issue that we can bump into when using binaural sound. This is because every part of the signal chain can cause this effect. Since our ears have a very unique way to interpret the sounds that come in, the smallest timbral coloration might translate into insufficient or hampered HRTF data. As a result, this potentially affects the binaural experience of the listener, complicating the reproduction of the intended sounds.
