You can quickly mute the iPad so that it immediately go into silence instead of the sound gradually fade out. Normally to turn down the audio sound you would press the down volumn button to turn off the sound, but this can take sometime, you could use the side switch button instead. You can set different functionality to the side side switch, by default it as been set for screen rotation lock. If you want to assign the lock sound functionality to the side switch here's how:
1. Press the Home button to go to the Home screen.
2. Then tap on Settings.
3. Select General.
4. Now select Sounds.
5. Near the bottom of the screen set the Lock Sounds switch to the On Position.
Note: The side switch is just above the volume button.
Now you can slide the side switch to quickly enable or disable the audio sound.