VoiceSpeaker.cs

using System.Collections.Generic;
using UnityEngine;

public class VoiceSpeaker : MonoBehaviour
{
    private List<float> _buffer = new List<float>();
    private object _lockObject = new object();

    private AudioSource _source;
    private AudioClip _speakerClip;

    private const int SampleRate = 16000;
    private const int RecordingTime = 1;

    void Start()
    {
        _source = GetComponent<AudioSource>();
        _speakerClip = AudioClip.Create("Speaker", SampleRate * RecordingTime, 1, SampleRate, true, OnAudioRead);
        _source.clip = _speakerClip;
        _source.loop = true;
        _source.Play();
    }

    public void RecvData(List<float> data)
    {
        lock (_lockObject)
        {
            _buffer.AddRange(data);
        }
    }

    void OnAudioRead(float[] data)
    {
        System.Array.Clear(data, 0, data.Length);

        if (_buffer == null) return;

        lock (_lockObject)
        {
            if (_buffer.Count < data.Length) return;

            for (int i = 0; i < data.Length; ++i)
            {
                data[i] = _buffer[i];
            }

            _buffer.RemoveRange(0, data.Length);
        }
    }
}