音を鳴らすスピーカーを選択して音声ファイルを再生。数字,ファイル名、でそのスピーカーから音を再生。w,ミリ秒 でwミリ秒待ち。ビルドするときは、NAudio を nuget で追加してください。

PlayScript.cs

using NAudio.Wave;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace MultiSpeaker
{
    public class PlayScript
    {
        string[] _list;
        public PlayScript(string filename)
        {
            Initialize(filename);
        }
        public void Play()
        {
            for(int i=0; i<_list.Length; i++)
            {
                Console.WriteLine(_list[i]);
                string[] d = _list[i].Split(',');
                if(d.Length == 2)
                {
                    if (d[0].Trim() == "w")
                    {
                        Thread.Sleep(Convert.ToInt32(d[1]));
                    }
                    else
                    {
                        PlaySound(d[1], Convert.ToInt32(d[0]));
                    }
                }
            }
        }
        public void PlaySound(string filePath, int index)
        {
            var waveReader = new NAudio.Wave.WaveFileReader(filePath);
            var waveOut = new NAudio.Wave.WaveOut();
            waveOut.DeviceNumber = index;
            waveOut.Init(waveReader);
            waveOut.Play();
        }

        private void Initialize(string filename)
        {
            _list = File.ReadAllLines(filename);
            string[] device = GetDevices();
            for(int i = 0; i < device.Length; i++)
            {
                Console.WriteLine($"{i} = {device[i]}");
            }
        }
        private string[] GetDevices()
        {
            List<string> deviceList = new List<string>();
            for (int i = 0; i < WaveOut.DeviceCount; i++)
            {
                var capabilities = WaveOut.GetCapabilities(i);
                deviceList.Add(capabilities.ProductName);
            }
            return deviceList.ToArray();
        }
    }
}

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MultiSpeaker
{
    class Program
    {
        static void Main(string[] args)
        {
            var p = new PlayScript("script.txt");
            p.Play();
            Console.ReadKey();
        }
    }
}

script.txt

0,1.wav
w,5000
0,2.wav
w,5000
0,3.wav
w,5000
0,4.wav