I am running sonar Jan 2017.
I want to loop and record, where each loop is immediately audible so I can play over it.  This is so I can switch instruments in a live situation and play over the prior tracks (like a looper).   According to the help file, I should be able to immediately here the prior loop(s) if I use the sound on sound mode.  However, it is silent.  If I stop and rewind, it is all there and playing back, but I want to do this on looping.  Am I missing something?  Help is greatly appreciated.  

Last I checked it doesn't work that way with audio. Midi recording sound on sound does IIRC.

If you want to do audio looping try Mobius. 
 
http://www.circularlabs.com/
 
 
 

I'm a bit confused on this as well.  The other night I was trying to record a counterpoint along with what I had already recorded by using take lanes.  If I hit play, I can hear the other recorded midi tracks and play along, but if I record, the original [T1] take lane is silent.  I had sound on sound selected and according to what I've read, the T1 track should be heard as I record an accompaniment on T2.

Have you tried unchecking "Create new lanes on overlap" ?

If you don't need every loop (take) in its own lane than give this a shot.

Chuck, That didn't help.  I might be misinterpreting the purpose of take lanes feature to begin with.  Somehow I thought it would work that way. For now I'll just go back to the old fashioned way of doing it and just insert some additional midi tracks. Not sure if my problem is the same as Geoffrey's. Thanks for your help.

It works, I have used it many times. 
 
Watch this video
 
If you are recording midi, each instrument has to be on a separate channel, not omni.
 
Loop recording in Sonar

The video states that in overwrite mode all takes except that last one are muted, implying that they are not in sound on sound mode.  The manual explicitly states this.  In the help file page for "comping methods," there is a table.  One column is labeled "Hear existing material while recording?," in the the row for sound on sound, it says "yes."  Therefore I'm flummoxed. (Mobius really won't give me all the capabilities I want).  Perhaps this means only for midi, but it ought to work for audio.  Surely such a simple thing ought to be possible.  I have tried every permutation of the options in the recording settings page.  Insights?

The audio sound on sound has never worked like a looper when I have tried it.
 
The reference guide says
 

Not sure what everyone else is doing, but this is how I perform loop recording in Sonar Platinum
 
In Preferences > Project > Record
 
I select the following:
 
Comping
I select Auto Punch and check off "Mute Previous Takes" and then uncheck Auto Punch
Store Takes Lanes in Separate Tracks
Create New Lanes on Overlap
New Take Lanes on Top
Do not Group Tracks
 
Once this is configured, I save the project and then close and re-open the project. (May not be needed, but that's just me.)
 
I select the desired loop points. 
I insert my Soft Synth
Arm the track and begin playing the synth.
On each loop pass, I only hear the part that I an playing and the previous parts played have been muted and are in take lanes.
 
Try it.