Simply put, spatial sound is how we hear in the world. Although most of us are never quite aware of it, sounds tell us a lot about the space we are in. We interpret and incorporate this information quickly without ever being aware of it.
Objects emit sounds in the world around us, and sounds reflect off the surfaces and give us information about the space. For instance, you most likely could tell the difference between a carpeted and a hardwood floor in a space without seeing it. You could likely tell whether a room has a high vaulted ceiling or a much lower drop ceiling.
Our brain can interpret even the smallest details in the sound. The amount of time between a sound reaching your left ear versus your right ear can tell you tons of details about your space; subtle noise and shifts that get picked up and filtered through those sounds in the movement tell us other details.
One of these important filters is what we call Sound Occlusion. If an alarm is going off two rooms away, through multiple doors, as you move closer to the source with fewer obstacles occluding, or filtering, the sound from your ears, not only does the sound gets louder, but it also sounds fuller.
For HoloLens, Microsoft has created the MS HRTF Spatializer, where HRFT stands for Head-Related Transfer Function and is designed to help simulate the elements of real-world spatial sound.
With that very loose understanding behind us, because if you are reading this you likely do not want to learn to be a sound engineer yourself, we need to start a new scene and set up our MS HRTF Spatializer.
As before, open the Chapter2 scene, delete the Platform, Hello, and World objects from the Hierarchy and save it as Chapter 5.
We now need to go to our audio setting and change the spatializer to the MS HRTF Spatializer, as follows:
- Click on the Edit option on the main menu. Move down to Project Settings and click on the Audio option:
- In the Inspector, look for the Spatializer plugin, click on None, and select the MS HRTF Spatializer:
Now, we are ready to start working on Spatial Sound on the HoloLens.