When I got my iPad I put some mp3 files on it and listened to them (having bought the special extra widget required to do so, the thing not having a simple USB connection), and YouTube worked as did a few other things. Then I put some apps on it. Some worked and some didn’t. Skype did but I supposed that some others needed to be connected to loudspeakers. As the main one that I wanted was music from the radio, I got a cable to connect it to a proper speaker system. It still didn’t work. The manual said nothing about this. All the technical information it gives is:
You can listen to audio from the built-in speaker, headphones attached to the headphones port, or wireless Bluetooth stereo headphones paired with iPad. When headphones are attached or paired, no sound comes out of the speaker.
Not much use if no sound comes from internal or external speakers or headphones. After a session with Google I found the answer. You press the Home button twice. This reveals a task bar. You scroll to the far left of this task bar and find a set of audio control buttons. The speaker icon is set to mute by default. You unmute it and then everything works fine.
Brilliant. Nice one Apple. Almost as good as your maps!