If you are using a smart phone (like an iPhone) and listening to AM radio, in some circumstances this creates problems that you’ll want to be aware of.
Most (but not all) AM radio stations broadcast on only one channel. Since people don’t like to hear the radio station in only one ear, most (but not all) AM radio stations that are mono-only stream their AM signal as “dual mono”, meaning they want the player to take the mono signal and cause it to come out both speakers.
Great if you are using speakers – but not so good if you use the built in speaker on the iPhone – there is only one speaker.
The iPhone recombines the sound of both speakers into one speaker – which causes the signals to cancel out each other – resulting in a very weak signal that is only picking up small distortions between the two inputs. Sometimes the radio station is streaming in stereo and will suddenly start to sound “normal” (like during a network newscast).
If you listen on earbuds, everything sounds normal, because the phone isn’t combining two identical signals into one speaker.
I’m not an electronics guru, so I probably have the explanation slightly wrong. But if you hear gibberish on the phone, and plug in ear buds and it sounds normal, that’s why. I’ve generally been excluding those stations from appearing on the list of stations if I detect you are using an iPhone, but I’m sure I’ve missed a lot of them.
