Microphone input tails off when sustained

Unity Engine
1

Hi All, I’m working on an app where I need to record my voice and play it back. When the input is sustained (e.g. a long whistle or continuous singing) there is a problem where the recording fades out after 1-2 seconds. So when playing back the recording the audio is perfect for 1-2 seconds and then the volume seems to fade to 0 over the course of around 1 second. If I make a sustained sound for a time, pause, and then repeat, the same thing happens twice - fine at first and then fade.

I’ve tried this with 2 microphones and with the app below and a 3rd party app (MicControl 2 demo). Getting the same each time.

Setup - Unity 5.4.1, Windows 8.1

Any thoughts before I submit this as a bug?

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(AudioSource))]
public class MicrophoneTest : MonoBehaviour
{
    AudioSource src;
   
    void Start ()
    {
        src = GetComponent<AudioSource>();
    }
   
    void Update ()
    {
        if (Input.GetKeyDown(KeyCode.F1)) // start recording with F1
        {
            src.clip = Microphone.Start(null, true, 10, 44100);
        }
        if (Input.GetKeyDown(KeyCode.F2)) // Stop recording and play with F2
        {
            Microphone.End(null);
            src.Play();
        }
    }
}
2

It appears this is an audio enhancement that is part of Windows. It’s a noise cancelling feature. Very frustrating as it kind of limits my project. The solution I found involves altering settings in the Microphone properties in the control panel. Annoyingly this option is not on my system, even after reinstalling drivers. It appears you can potentially override this from an application. Does anyone know if this is possible from a Unity app? This is my first attempt at Unity. Is it possible to do these more low level things or are we more limited?