TestMic.cs

using System.Collections;
using UnityEngine;

namespace Assets
{
    public class TestMic
        : MonoBehaviour
    {
        // Set an explicit input device here. leave as null to use the default.
        public string MicName = null;

        private AudioClip _clip;
        private AudioSource _source;

        private void Start()
        {
            //Get device capabilities and choose a sample rate as close to 48000 as possible.
            //If min and max are both zero that indicates we can use any sample rate
            Microphone.GetDeviceCaps(MicName, out var minFreq, out var maxFreq);
    
            var sampleRate = minFreq == 0 && maxFreq == 0 ? 48000 : Mathf.Clamp(48000, minFreq, maxFreq);
            Debug.Log($"GetDeviceCaps name=`{MicName}` min=`{minFreq}` max=`{maxFreq}`");
    
            // Start capturing audio from mic
            _clip = Microphone.Start(MicName, true, 10, sampleRate);
            if (_clip == null)
            {
                Debug.LogError("Failed to start microphone capture");
                return;
            }

            StartCoroutine(WaitForMicClip());
        }

        private IEnumerator WaitForMicClip()
        {
            // Wait for recording to start
            var count = 0;
            while (Microphone.GetPosition(MicName) <= 0)
            {
                if (count % 10 == 0)
                    Debug.Log($"Waiting for recording to start ({count})");
                count++;

                yield return null;
            }

            _source = GetComponent<AudioSource>();
            _source.loop = true;
            _source.clip = _clip;
            _source.Play();
        }
    }
}