AudioSource.spread
var spread: float;
float spread;
spread as float
Description

Sets the spread angle a 3d stereo or multichannel sound in speaker space.

0 = all sound channels are located at the same speaker location and is 'mono'. 360 = all subchannels are located at the opposite speaker location to the speaker location that it should be according to 3D position. Default = 0.
	// when any AudioSource goes trough this transform, it will set it as 'mono'
	// and will restore the value to 3D effect after exiting
	// Make sure the audio source has a collider.
	function OnTriggerEnter(other : Collider) {
		 if(other.audio)
			other.audio.spread = 0;
	}

function OnTriggerExit(other : Collider) { if(other.audio) other.audio.spread = 360; }
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void OnTriggerEnter(Collider other) {
        if (other.audio)
            other.audio.spread = 0;
        
    }
    void OnTriggerExit(Collider other) {
        if (other.audio)
            other.audio.spread = 360;
        
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def OnTriggerEnter(other as Collider) as void:
		if other.audio:
			other.audio.spread = 0

	def OnTriggerExit(other as Collider) as void:
		if other.audio:
			other.audio.spread = 360