Determining if recording is stereo

How do I determine if a recording is actually a true stereo signal taken directly from a cassette player. I was able to record with the preferences set to mono. After changing to stereo, it appears that I have 2 separate signals according to image. Is it really 2 channels or a mono signal that is being duplicated. Using a Dell Inspiron 1525 laptop with sigmatel sound.

As far as i can remember if you have recorded as a stereo track you will have 2 identical (or pretty close to) waveforms and on the left you will only have one set of gain and pan sliders etc.

if you have two copies of a mono recording each wave form will have its own set of gain and pan sliders etc.

make sense?

to see what i mean go to

the top left image is two mono the top right image is a stereo recording

You are right, but I am still not sure how to verify that each channel shown in stereo has different material or signals. If the original source has predominate vocals on left and instrumental on right, are they being mixed into one signal and then split into 2 channels or tracks?

The easy answer is to blow up the timeline waveforms with the magnifier tool. A “real” stereo signal has left and right wiggles in the waveform that very clearly don’t match. Two Track Mono will have identical waves.

The compulsive will want to split the stereo track, invert one track and add the two. A two-track mono signal will vanish–completely cancel–if you do that.

My Spidey Sense is telling me you convinced your PC laptop to record a stereo performance by plugging sound cables into the Mic In. Microphone connection on laptop computers are mono. You probably didn’t get the right channel of the performance at all.


I hope your spidey sense is incorrect. That is the reason for my doubt. Here is what I have done since. While recording directly from cassette player with rca patch cables on player to mic in plug on laptop, I alternately disconnected right and left plugs. With each disconnect, the corresponding channel lost its signal. ON play back, right and left speakers cut in and out in sync with waveform.

As far as fooling laptop, when I plug in patch cord to mic input, I get the option to choose line in or mic. So as you can tell, I think I am still confused, but it does sound and look like a stereo signal.

Cool. Or cooler than you think. You have a laptop that can switch successfully between a microphone type of connection and a high-level Line-In.

There is a trick to doing what you did. Launch Audacity and once it arrives, click once anywhere inside the red record meters. They should wake up and start monitoring the input level without you actually going into record and wasting hard drive space.

Then unplug the RCA cables from the amplifier or radio and touch first one tip and then the other with your finger. Hold the connector with your other hand on any rubber or plastic part. The corresponding sound channel will bounce when you do that if everything is OK. You are intentionally creating trash and distortion on each channel just long enough to make sure the channel is running.

Then plug it all back together.

It certainly appears that Audacity and your computer are running perfectly well. Why do you suspect that your show is in mono?


What that does in Audacity is record from the Left connection and ignores the Right. I believe it produces a single mono sound track, too. With reference to my web page with the illustrations, Microphone signal in one configuration turns out to be “Left Audio” on the other.

Also, I have several nice microphones that have their own battery. In that case, the connector has no ring connection. Just the shield and tip. A “SoundBlaster” type of sound card is designed to tolerate this kind of connection. You can plug any type of microphone in there.


Thanks, I feel lucky as it sounds good on playback and comparing waveforms visually, they do appear to be different and after max zooming, there is marked difference. I do feel like it is capturing a stereo signal. BUT you did bring out the compulsive in me. I am able to split tracks, invert one, but cannot figure out how to ADD them together.