There are 2 file types use the .MUI file extension:
1. Myriad User Instrument File
An MUI file is a user instrument file used by Myriad musical notation software products such as Harmony Assistant. It stores sounds for a variety of instruments such as piano, strings, woodwinds, brass. MUI files are used for generating realistic sounds.
|Myriad Harmony Assistant||Freeware|
Updated: September 24, 2017
2. Multilingual User Interface File
Resource file used by the Multilingual User Interface component of Windows 2000 and later; contains resources that allow the Windows interface to be changed to different languages.
Many MUI files can be found within the Windows %SystemRoot%\ directory (e.g., %SystemRoot%\en-US\ in Windows 7). They may also be located within specific program installations, such as Windows Journal, Windows Defender, Windows Mail, and other Microsoft Windows programs, including Notepad (notepad.exe.mui).
Additional language packs can be installed in Windows 7 by selectingand clicking the button.
|Microsoft Windows Multilingual User Interface||Free|
Updated: August 17, 2010