Loudness

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Author: Jessy

Description

Unity's AudioSource.volume and AudioListener.volume use what is known as a linear taper. Although that is ideal for performance, it means that the 0-1 values that those properties utilize do not match up well with human perception, with loud values taking up a disproportionate amount of the range. This script is designed to make working with loudness more intuitive.

Loudness is a complex phenomenon, and this simple script does not, for instance, take equal-loudness contours into account, but it should yield better results than a linear taper in every real-world case. I've found the result described here, that "a 10 dB increase in sound level corresponds approximately to a perceived doubling of loudness", leads the way to a highly usable loudness control.

Instructions (C# only*)

Add this script to your project, wherever you like. It's a static class, so you neither need nor have the ability to attach it to a Game Object.


Loudness.OfListener (which alters AudioListener.volume) is a property, so you can assign a 0-1 value to it, or get one back, using the equals sign.

Loudness.OfListener = .5F;  // Half as loud as it can get


Extension properties do not exist in C# yet, so for instances of Audio Sources, you have to use separate get and set methods.

audio.SetLoudness(.5F);  // Affects the AudioSource attached to this Game Object
someAudioSource.GetLoudness(); // gives you a better idea of the portion of maximum loudness than someAudioSource.volume


  • A UnityScript alternative would have to be more verbose, due to lack of properties and extension methods in that language (at present), but feel free to add a JS solution to this page.  ;-)

Loudness.cs

using UnityEngine;
 
public static class Loudness 
{
	// A 20 dB increase sounds about 4x louder.
	// A signal needs an amplitude that is 10^(dB/20) greater, 
	// to be increased by 'dB' decibels.
	class Exponents 
	{
		public static readonly float Set = Mathf.Log(10, 4);
		public static readonly float Get = 1 / Set;
	}
 
	public static float GetLoudness(this AudioSource audioSource) 
	{
		return Mathf.Pow(audioSource.volume, Exponents.Get);
	}
 
	public static float SetLoudness(this AudioSource audioSource, float value) 
	{
		return audioSource.volume = Mathf.Pow(Mathf.Clamp01(value), Exponents.Set);
	}
 
	public static float OfListener 
	{
		get 
		{
			return Mathf.Pow(AudioListener.volume, Exponents.Get);
		}
		set 
		{
			AudioListener.volume = Mathf.Pow(Mathf.Clamp01(value), Exponents.Set);
		}
	}
}
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