// Prints how many channels the attached audio source has
// 1 --> Mono
// 2+ Stereo
Debug.Log(audio.clip.channels);    

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        Debug.Log(audio.clip.channels);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        Debug.Log(audio.clip.channels)