Binaural
Binaural is a 3D sound rendering technique, dedicated to headphone listening. Its working principle is based on individual auditory characteristics, called HRTF (Head Related Transfer Function).
Please note that a Binaural Spatialization Bus is not the same as the Binaural Monitoring Bus.
A Binaural Bus allows you to create native spatialization on headphones whereas Binaural Monitoring allows you to simulate your loudspeaker setup over headphones.
With Binaural Monitoring, you can monitor any spatialization bus based on Amplitude Panning or Ambisonics algorithms. This allows you to work on a spatialization project with your headphones only.
How it works
Our hearing system uses time and intensity differences to determine the localization of a sound. But the shape of our ears, head and torso also has an impact on the sound arriving to our eardrums, by causing small reflections and filtering. These characteristics are unique to every individual.
Binaural relies on HRTFs (Head Related Transfer Functions), consisting of measurements of these characteristics for several spatial positions. By recreating those auditory cues via headphones, it enables the user to position a sound in 3D, anywhere around the listener.
Settings
Audio Tab
Binaural Buses contain one additional setting in the Audio Tab compared to other algorithms.
Headphone EQ
Any monitoring headphone will introduce a modification of the outgoing signal’s frequency reponse. But signal frequency response is very important for binaural to properly function and create a convincing 3D image.
HOLOPHONIX therefore offers to choose amongst 23 EQs corresponding to professional monitoring headphones to compensate for their natural EQ. This allows for a better localization perception.
Algorithm Tab
All of those parameters are available in the Algorithm Tab of Binaural Buses.
ITD
The ITD (Interaural Time Difference) parameter allows you to adjust to your morphology to the interaural time difference that is due to the distance between your ears.
HRTF
To configure a binaural bus, simply choose an HRTF File from the list. The ‘1040’ HRTF file is provided by default with HOLOPHONIX as it is known to ensure good results for many people.
Different versions are available for the '1040' HRTF: SOS16 (lower spectral quality, more CPU efficient), SOS24 and SOS32 (higher spectral quality, more CPU demanding).
Click on “Import HRTF File” to load any custom or open-source HRTF file as long as it matches the preset’s sample rate.
Orientation
The orientation of the Binaural Listener can be adjusted with Yaw, Pitch, Roll, to rotate the entire audio scene. See rotation angles.
Head tracking systems can be connected to a binaural bus (including the monitoring bus) through OSC. These systems track the head orientation thanks to a small device (some iOS or Android apps offer such functionalities).
It allows keeping the audio scene at the same position around you, even when moving your head. This generally greatly helps with hearing the right localization for the sounds.