Symptom
You may hear a high-pitched noise during a song's silent passages. This only occurs with MP3 files and is most noticeable when the volume is set higher than 75 percent.
Note: Most people are not able to hear this sound. iPod itself is functioning normally.
Solution
Update iPod to iPod software 1.1 or later. The updater is available from Apple Software Downloads (
http://www.apple.com/swupdates/).
Lowering the volume may minimize the noise with MP3 files.
AIFF and WAV files are not affected since they do not use the MP3 decoder.