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The Audio Listener component is the equivalent

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of your ears in the game.

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It receives, or listens, to audio sources

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that are in the game world.

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The control of the audio's behaviour is done on

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the audio source component

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and therefore the listener itself has no settings.

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This is attached to a camera in your scene by default

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but can be placed on any object.

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Often this is attached to a character

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and crucially there can be only one listener

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per scene in order for it to function correctly.

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You can test an audio listener from any position in the world

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by moving the scene camera around

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with the audio preview toggle enabled.

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This gives you live testing of audio sources

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in your environment without having to move

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the real listener or play test the game.

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Audio sources are components that playback audio.

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Think of them as speakers in the game world.

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In this example our turbine has an audio source attached

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with the turbine audio clip that's been applied to it.

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We can assign a clip by dragging and dropping,

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or by using code to select a clip to play.

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We can mute, bypass any filters,

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choose whether to play this audio source on awake,

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as in - when the game begins

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and whether to loop the clip.

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Priority varies between 0 and 255,

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0 being the highest priority.

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It's advisable to have music set as the highest priority

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to avoid other clips from overriding

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when many clips are being played at once.

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Volume determines how loud the clip is played

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based on it's original waveform.

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Pitch controls the pitch of a clip.

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If you're working with 3D sounds

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the settings are more detailed.

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Doppler level defines how much the Doppler Effect

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will be used.

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This is a perceived shift in frequency as the listener

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or the ear in real terms

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is moving past the sound source.

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It will seem higher approaching it

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and lower as it moves away.

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Think of an emergency vehicle's siren as it passes you

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for example.

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Volume roll-off determines the type of roll-off

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to be used by the sound

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as the listener moves away from it.

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This can be logarithmic, linear,

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or customised manually using a curve

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and adding keys as shown.

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The minimum distance defines how close

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to play the sound at full volume.

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So if you are designing 3D sound

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use this value to make the sound source louder.

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This can be adjusted using the spherical Gizmo

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in the scene view.

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And it works in the conjunction with the

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maximum distance setting below,

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which by default is set to 500 metres

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and is a distance after which

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the sound rolls off.

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Pan level defines how truly 3D the sound is.

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This defaults to 1 for 3D sound

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making it fully panned when the stereo listener

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is moved past it.

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Spread is the control of the angle of spread

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from 3D stereo to multichannel sound.

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Finally for 2D sound pan can be controlled

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at the bottom of the component.

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As a rule elements such as music

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should be set to 2D sound,

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whilst diegetic sound that should be

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fading realistically should be set up

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as 3D and positioned accordingly.

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The 2D and 3D values of a sound

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are controlled by an audio clip's import settings.

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When selecting a clip in the project

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you will be able to see the import settings

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in the inspector.

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You can choose the audio format to use,

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whether it should be 3D or 2D sound,

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whether you want to force your stereo sound to mono,

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how to load it and what compression to use.

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You can also preview sound at the bottom,

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choose whether to loop whilst previewing

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and set the inspector to auto-play

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whilst browsing through clips.