Standard MIDI Files (SMF) contain instructions that trigger sounds played by a synthesizer which is typically expected to meet the General MIDI specification. On a personal computer these instructions can be turned into sound by either a software synthesizer, or by sending them along to a hardware synthesizer.
There can be remarkable differences in the sound produced by a MIDI file, depending on the machine on which it is played and the instrument samples it uses.
On Wikipedia, it is possible to play MIDI files, but only through an extension. Some pages will not utilize the extension to play MIDI files, so you will either have to download the file or edit the article.
The following problems might occur when playing MIDI files:
The machine on which you play the file must have both the software and hardware required to play MIDI files. This is natively supported in Windows, used to be built into Macintosh computers by default. Now you may need to install additional software.
Your sound card mixer playback settings might need to be changed. You can enable and unmute all playback devices, and then increase the volume of all of them, to ensure that your sound card sends MIDI audio to its output.
MIDI files encoded with a more recent version of the MIDI standard might not be correctly rendered if your machine doesn't support that version of the standard.
Some hardware manufacturers produce proprietary extensions to the general MIDI standard that are not rendered by all MIDI players. Such hardware-specific extensions are to be avoided in MIDI files uploaded to Wikipedia.