How to listen to the other person singing ?

I take it that your headphones are plugged into the interface? Is there a way to switch between the signal that goes into GB and the one that comes from GB?

The easiest solution for your problem: get a little splitting adaptor that allows to plug in two sets of headphones and plug it into the computer's headphones jack. In both tracks, turn on monitoring in the info pane. Now both singers should be able to hear both vocal tracks in their headphones.

There are a couple of things you have to be aware off:

Speakers vs headphones.

GarageBand has only one output signal. Regardless where you send that signal (computer out, USB interface, etc) it is one signal. If you hooked it up to a speaker and headphone(s), they should all have the same signal. If two singers listen to the same GarageBand output and they claim they hear different singals, that is not possible.

Multitrack Recording

I assume that you have Multitrack recording enabled in GarageBand so you can record the two singers on two different Tracks.

Monitoring.

What Christoph is referring to is the Monitor setting on your Track. The Electric Guitar Track has this button visible on the Track Header automatically but a Basic Audio Track does not. You have to enabled it in the Track Menu. That's where you also enable MultiTrack Recording

Once you made the Monitor button on the Track Header visible, you can choose to set Monitor on or off. Click on the button to open a little popup menu with the option. You have to turn Monitoring on so the microphone signal reaches the output (and the headphone of the singer).

The feedback options helps if you are recording a microphone in the same room whee you listen to the monitor speakers.

Hope that helps

Edgar Rothermich

http://DingDingMusic.com/Manuals/

'I may receive some form of compensation, financial or otherwise, from my recommendation or link.'

Speakers vs headphones.

GarageBand has only one output signal. Regardless where you send that signal (computer out, USB interface, etc) it is one signal. If you hooked it up to a speaker and headphone(s), they should all have the same signal. If two singers listen to the same GarageBand output and they claim they hear different singals, that is not possible.

I think it is possible with his Liquid Saffire Pro 56. The mixing/routing software that controls the interface does allow routing of input signals to the two headphone outputs. I never used one but it is really flexible piece of hardware.

Yes, Audio Interfaces usually provide their own little mixer/routing and many musicians use that especially for recording to create a monitoring/headphones setup or just to eliminate the latency when listening "through" the DAW.

Using those external mixing and routing options makes it even more important to have the proper Monitor setting in GarageBand.

If you don't see it you may be using a older version of garageband. If this is the case these options are on by default.