Is there a way to listen to the input sound on Mac OS X?

Question

Is there any easy way to listen to the input on a mac?

For example, assume I have a microphone hooked up to the input (i.e. line in) of my mac, and I have headphones hooked up to the output of my mac, is there any way that I can hear what I say in the microphone through the headphones?

This is very easy in Windows XP, simply by going to the sound settings for recording devices, checking "Select" on the Line In and increasing the volume. Which makes it so you can hear what is said into the microphone.

It has to be in real time, a solution where you record the input and then playback the output later doesn't help.

Answer 1

Take a look at Rogue Amoeba's LineIn. It is a free application which will allow you to do what you want.

Answer 2

If you're using an older Mac, the application Audio MIDI Setup.app in the Utilties folder (found in the Applications folder) allows* the ability to pass-through input straight to your output.

To do so; click on your input device and then check off the "Thru" checkboxes to pass audio through. However oddly enough I've never seen anyone to get it to correctly work on an Intel based Mac, I've had it work great on some PowerBook G4s however.

The better alternative is to use Rogue Amoeba's LineIn (as said by Richard Hoskins). Personally I use this and find it easier to use.