Okay, so filters are another thing that we need to be aware of, audio filters I've already described to you, but what can we actually do with them? Well, they're really good for adapting sound effects. An example of a filter might be a picture filter. Let's imagine that we've got a sound effect of a gunshot, and I'm shooting someone with a gun like this. If the sound is always the same, it actually lacks realism. If I vary the pitch a little bit while I'm doing this, it might make it sound like each bullet is coming out in a slightly different way. These sorts of effects, they can make the whole scene seem more real. Other examples of audio effects include things like adding noise or filtering, reducing the sound, making it sound like a sound is coming from behind a wall. So, for example, if we move out of one room and into another room, we might want to apply a filter, ambient sounds, for example, that are going on in a room that we just left. Another important thing that we need to consider is how we process speech using filters in VR. So we might want to vary the quality of the speech based on the environment that we're in. If we're outside, generally speaking, when you're outside, you have less bass in the voice. So a good idea is to roll the bass off when you're trying to create the environment of a massive open space. All the bass is coming out, all the bass frequencies, low frequencies are coming out from the voice, and they're just going off into the atmosphere, and they don't reflect back at you. Now, normally, if you just take the bass off, you roll the bass off audio, it makes people think that you're outside, and this is a really powerful way of creating that effect. Other things you can do with voices is you can make something sound like it's coming from a radio. So you might want to record the whole thing cleanly in a studio with a nice mic, and then affect it with some kind of filter and maybe a bit of distortion, to make it sound like someone's communicating with you over a telephone or over a radio. This is a technique which is used all the time in virtual game worlds to change the environment and setting. Another thing you can do with filters in VR is you can process music. This is great for, for example, changing the atmosphere and making it more exciting. A common thing that musicians do to build up a piece of music is they open a filter. So what that means is you start a piece of music and it sounds very dull. And then slowly, over time, you increase the high frequency content so that you get the sound of it rushing and becoming more exciting. So it goes from a kind of sound to a sound and this whoosh sound is really good for generating feelings of excitement because the brightness, the more brightness you have as that brightness increases, the more present everything sounds.