EditorApplication.Beep

Description

Plays system beep sound.

// Play sound on mouse down event
function OnGUI () {
    if (Event.current.type == EventType.MouseDown)
        EditorApplication.Beep();
}

/ Play beep sound on menu click

using UnityEditor;
using UnityEngine;

public class BeepExample
{
    [MenuItem("Examples/Play beep")]
    static void DoBeep()
    {
        EditorApplication.Beep();
    }
}