Make sure that only one source is selected in GoldWave (press F11, Volume tab). If multiple sources are selected, they may be a source
of noise. Also use the correct source. If you are recording Line In,
then select that instead of things like Stereo Mix or What You Hear,
which involve multiple inputs.
Check that all connections are firm and that no cables are damaged.
Make sure you are using proper cables (stereo cables have three sections on the plug).
Try selecting a different quality setting in GoldWave (press F11, Device tab). Normally "PCM 16 bit" quality must be selected unless
you have a 24 bit sound card that actually works.
For stereo recording, make sure you select the Stereo option when creating a new file for recording.
Update the sound driver if it is listed as "emulated" in GoldWave (press F11, Device tab).
Try recording in the Windows Sound Recorder accessory to see if that has the same problem. If so, the driver or hardware may be