Partial loss of sound

I have this problem that after SL has been running for a while, some sounds drop out. Ambient sounds like wind, birds, water are unaffected, but foreground sounds, especially the typing sound, cease to be audible.

I can fix it by relogging, but there's always the risk of not being able to log back on.

Can anyone explain why this is happening, please?

Hi Daisy, something I observed recently is the 'microphone' follows the 'camera'. Pretty certain while I was observing something at a distant I couldn't hear my typing. Probably not your problem .. just a wild thought .. hell, it IS Monday

No, this is cutting out. Once it happens, I won't hear (e.g.) the typing sound no matter how close I am to the origin. But at the same time, the neighbourhood birds are chirping away.