Sound can be added to learning materials in a variety of ways. Most office applications allow sound to be directly embedded into files - for example, sound can be recorded into a Word document by clicking Insert > Object > Wave sound and directly recording a sound clip. Alternatively, the Windows operating system has a programme called Sound Recorder (normally under Start > Programs > Accessories > Entertainment) which allows files to be directly recorded and saved for inclusion in Word, PowerPoint or web files. MP3 files can also be recorded directly from digital voice recorders - for example those bundled with MP3 players. The links below explore different accessibility opportunities and constraints provided by sound files.