//1.

[DllImport("Kernel32.dll")] //引入命名空间 using System.Runtime.InteropServices;

        public static extern bool Beep(int frequency, int duration);// 第一个参数是指频率的高低，越大越高，第二个参数是指响的时间多

Beep(, );

//2.

 [DllImport("winmm.dll")]

public static extern bool PlaySound(String Filename, int Mod, int Flags);

PlaySound(@"C:\Windows\media\Windows Proximity Notification.wav", , );