unit ttSound;

interface

uses winapi.windows, winapi.Messages;

type
  SimpleSoundControl = class
    class procedure Mute(); static;
    class procedure VolumeUp(); static;
    class procedure VolumeDown(); static;
  end;

implementation

{ SimpleSoundControl }

class procedure SimpleSoundControl.Mute;
begin
  keybd_event(VK_VOLUME_MUTE, MapVirtualKey(VK_VOLUME_MUTE, 0), KEYEVENTF_EXTENDEDKEY, 0);
  keybd_event(VK_VOLUME_MUTE, MapVirtualKey(VK_VOLUME_MUTE, 0), KEYEVENTF_EXTENDEDKEY or KEYEVENTF_KEYUP, 0);
end;

class procedure SimpleSoundControl.VolumeDown;
begin
  keybd_event(VK_VOLUME_DOWN, MapVirtualKey(VK_VOLUME_DOWN, 0), KEYEVENTF_EXTENDEDKEY, 0);
  keybd_event(VK_VOLUME_DOWN, MapVirtualKey(VK_VOLUME_DOWN, 0), KEYEVENTF_EXTENDEDKEY or KEYEVENTF_KEYUP, 0);
end;

class procedure SimpleSoundControl.VolumeUp;
begin
  keybd_event(VK_VOLUME_UP, MapVirtualKey(VK_VOLUME_UP, 0), KEYEVENTF_EXTENDEDKEY, 0);
  keybd_event(VK_VOLUME_UP, MapVirtualKey(VK_VOLUME_UP, 0), KEYEVENTF_EXTENDEDKEY or KEYEVENTF_KEYUP, 0);
end;

end.

来源：https://www.cnblogs.com/cb168/p/6367310.html