AudioSource.dopplerLevel  

// Dont use doppler effects.

audio.dopplerLevel = 0;

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        audio.dopplerLevel = 0;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        audio.dopplerLevel = 0