If you can hear other sounds (i.e. scores playback) but no sound for metronome, probably the installed SoundFont is not able to generate all sounds in the General MIDI (GM) standard.
You probably already know what a text font is. It is used to change the appearance of the characters you type in programs such as Microsoft Word. Well you can think of a SoundFont in a similar way. SoundFont files contain sound samples of real instruments and other music synthesis parameters such as loops, vibrato effect, and velocity-sensitive volume changing. By changing the SoundFont used by your MIDI synthesizer you can control the sound it produces. So instead of hearing a crappy piano sound, you can replace the SoundFont used by your synthesizer to get the sound of a high quality grand piano.
Normally, the default SoundFont included in MIDI synthesizers covers the 128 sounds of General MIDI standard. But there are many SoundFonts available on the web with different file sizes and sound quality. If you have changed the default SounfFont, you could experience problems with LenMus if you have installed a SoundFont that does not conform to the GM standard. The most common problem is that sound for metronome is not generated.
To solve the problem you should either:
Last updated: 2014/07/24
LenMus