Why doesn't twitter or facebook have sound on iPad Air?
For Facebook:

First make sure this is done so that you can go on to the actual solution. Facebook push notifications are controlled inside the actual Facebook app under “Account Settings>Notifications”. They are NOT controlled under the iOS “Settings>Facebook>Settings>Notifications”, if you go there you will be directed to the actual Facebook app.

Now it’s time for the solution to the problem. There is one more step that you need to do that doesn’t turn on by default for some reason.

STEPS:


This starts from your iOS device home screen
“Settings”
“Notifications”
“Facebook”
Turn on the “Notification Center” – required to have the push notifications work
Under “Alert Style” by default this is set to “None” for some reason. So, turn this to the style you want.
Turn on the “Badge App Icon” – if you want to, this will display the number of new notifications on the Facebook icon, just like it does on your Messages app when you have a new text message
Turn on “Sounds” – if you want to, this will play a sound when a new Facebook notification comes in