These are usually plug-in devices like audio synthesizers, but might also be built into your computer.  Websites are normally not allowed to access MIDI devices. Improper usage could cause damage or compromise security.
这些通常是音频合成器等插拔设备，但也可能内置于您的计算机中。  通常网站不被允许访问 MIDI 设备。使用不当可能会造成损坏或危及信息安全。