# A "mathamatically right" way to control VCA fader with parameter in Unity integration

Hello!
I’m currently working on a in-game volume control option with Unity.
I made a global parameter to control the VCA fader, and wrote a graph between parameter value and VCA.

Here’s my question.
An image above is a graph that I drew.
If a graph is a straight line, when player set the volume slider 100 to 50, VCA fader goes straight down to -21.4dB.
And I think that is not a “mathamatically right” way.
Because, like everybody knows, -6dB is a half way down.

As far as I know, a decibel value can be calculated with logarithm function, 20logx.
But in FMOD there is no such way to draw a log graph, so I have to write a custom script in Unity.
And that should convert the “linear” parameter value to log value, and toss it to the VCA.
Some guy in YouTube also said that this is the “right” way.

What I want to ask is, is there any other option to do it in FMOD.
Like, the VCA fader is already scaled in linear value, so I don’t have to do this. Anything.
Or some other opinion from sound designer is welcome! Give me a feedback!
Thanks!

To explain why volume automation curves work the way they currently do: The logarithmic scale of deciBels means that the perceived difference between one deciBel value and the next becomes smaller at very negative deciBel values, or to put it another way, the difference between -70 and -76 dB is less significant and noticeable than the difference between 0 and -6 dB. Accordingly, we draw the automation curves such that the upper parts of any given automation track represent a smaller number of dB values, to give you greater fine control in the dB ranges where a small change means more, and coarser control in the ranges where a small change would be barely noticeable.

I can see why you might want to override this behavior in some cases, though. I’ll add your suggestion to our feature/improvement tracker.

Okay, so what I’ve understood is, the FMOD’s mixer fader is designed with consideration of psychoacoustic. Am I understanding correctly?

then now it’s up to me to what method i’m going to use. Thanks a lot!

That’s right.

As a practical matter, it’s rarely necessary for volume controls to be “mathematically right.” Most players are not trained to recognize the differences between volume attenuation curves, and even those who can do it are more likely to focus on tweaking the volume to a level they’re comfortable with than on identifying the curve in use. That being said, all games have unique requirements; if your game needs to display the precise volume adjustment, that’s another story entirely.

I see. learned a lot. Thanks for the answer.