Head Related Transfer Functions (HRTF)

Placing audio in a 360 environment can have it's challenges. There are many times when you place something in the 3D space and it doesn't sound like it's in the exact location that you've placed.


Or you'll place something, it'll sound good to you, and then when somebody else listens to it, to them it doesn't sound like it's placed quite right.


Are you crazy? Did you do something wrong? Is the program your working with broken?


No! Actually, it is likely to do with your Head Related Transfer Function (hereafter known as HRTF because that does not flow off the tongue).


What is an HRTF? Simply put, how your ears locate sounds is actually very unique to you. There are three main ways our body locates sounds...


1) The pinna, which is located in our outer-ear. It is the main function we use to place sounds in the 3D environment.


2) Our shoulders. Sounds that come from above us bounce off of our shoulders and into our ears.


3) Our chests. Sounds coming from below us will bounce off of our chest before hitting our ears.


As you can see, locating sounds is a very complicated thing! Just looking at these three aspects, it's easy to see how each individual will have a unique way of localizing sounds. How I do it is way different then how you do it.


So where does it leave us regarding 360 audio?


As you guessed, the HRTF is a personal measurement of how you located sounds. Think of it similar to a shoe size. By using a HRTF when mixing/placing sounds in VR you can


To get a personal HRTF done is a very involved process. It involves you going into an anechoic chamber and having a bunch of tests done on you.


Don't have access to these thousands of dollars worth of equipment? You're not alone.


Thankfully, there are plenty of free options for you to choose from as many universities make them available. My personal favorite resources is from the Research Institute of Electrical Communication at Tohoku University.


Now, the big problem (and a reason why these aren't a little more mainstream) is that there's currently no good way of organizing or labeling these. And as much I would love to be able to give you a set of guidelines to point you in the right direction, the best way to move forward is to simply download a few at random and see how they sound when you load them into whatever your favorite 3D audio program is.


You'll notice that it is much better than a generic HRTF that most programs come with. If you can convince your clients to find a good one for them as well, it can also


But, you may think, isn't this a little time consuming? Having to go through hundreds of HRTF's?


Nobody's got time for that! If you spend some time, you're likely to find something that is good enough fairly quickly. The quality varies from university to university as well (which is why I would recommend starting with RIEC). It'll also make you look like a total pro when talking with your clients.


So, to recap...

1) HRTF's are our personal way of locating sounds in a 3D environment. This is influenced by our pinna, chest and shoulders.

2) If you're unable to get your own custom HRTF, there are hundreds to download for free.

3) It will make you sound like a total boss when talking to clients.


Happy mixing!

©2020 by Alex Liberatore