I am still trying to work out what the cause of the problem is - I have not yet suggested a solution. I'm trying to eliminate a common cause.
You have a sound source - e.g. a guitar - plugged into your computer.
Many sound cards have a "local monitor" option which routes the sound coming in directly to the sound output.
That effectively bypasses the computer (and hence ninjam).
However, you must not do this. You will have to check your sound card settings to see whether it has this feature, whether it is on or off and how to turn it off.
Also, make sure you are using headphones that stop you hearing anything that is happening locally. The only way sound should get to your ears is through the sound card output (and hence your headphones).
Once the sound gets from your sound card it gets to ninjam somehow. I am assuming you are not using Reaper as you didn't list it. So I am assuming you are using the ninjam standalone client. (Reaper is much nicer.)
In the standalone client, when you connect, you will see your local channel(s) at the top and any remote channels for other participants on the server you have connected below, with chat to the right.
You should be able to hear three things:
- the metronome
- your local sound
- any remote sound
There is an overall mute "button" (check box). If you press this, you should hear none of the above.
Each of the above has its own mute button, too. So pressing that mute button should just stop you hearing that item. (Don't leave the metronome muted.)
The test you are doing here can use either the overall mute button or the local mute button(s) but either way, you should not hear yourself when these are muted.
The client can also record your session locally, which may help trying to work out what is happening - see Options->Preferences.
The public servers are listed on the Cockos ninjam site. Go to
http://www.cockos.com/ninjam/ and click the link labelled "public servers" at the top.