Last month, you gave me some advice on identifying why the vocals on my track weren't audible when I played it in my car [see last month's answer to this by going to /sos/aug12/articles/qa-0812-5.htm]. However, I've since discovered something that I thought you might be interested to know about. I have the iPod plugged into the car via one of those radio transmitters, powered by a cigarette lighter, which you tune into the car radio. It would seem that the car was picking it up in mono.I retuned the transmitter and the iPod was picked up in stereo. I never realised just how wide it would be in the car. My monitors and headphones don't show up the full effect very well. So do you have any advice as to what to do now?
Via SOS web site
SOS Technical Editor Hugh Robjohns replies: Ah yes: stereo FM radios revert to mono if the signal reception is weak. This is a deliberate design ploy to minimise audible noise during weak reception.
What it demonstrates is that your mixes have very poor mono compatibility, and that is often the case when you use a lot of stereo-widening or width-enhancing techniques and tools.
I suggest you invest in a hardware or software phase meter and learn to mix your material to keep the meter on the positive side of zero. This should ensure a reasonable degree of mono compatibility. Headphones aren't the best for this, because each ear only hears the sound from that earpiece: it's called binaural listening and is a completely unnatural experience. Consequently, the brain processes the sounds in a different way to normal, and stereo imaging perception goes right out of the window. There are various headphone monitoring systems involving clever crosstalk systems to try to overcome this problem. Listening over monitors, both ears hear the sounds from both monitors, and that produces an impression that is more like real life. It's still an illusion and is still fooling the brain, but it works rather better.
I'm surprised you hadn't noticed how wide the stereo was on your monitors. That would suggest either that your monitors aren't very good, or that you have polarity or phase issues with them, or — more likely — that you have poor acoustics in your listening environment, with a lot of strong local reflections that mess up the imaging.