Why my iPad speaker crackle?

It might just be a software fluke. Try this and see if it helps. You will not lose any data.

Reset the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider if it appears on the screen - let go of the buttons. Let the iPad start up.

iPhone: No sound or distorted sound from speaker

http://support.apple.com/kb/ts5180

To solve some sound problems, just follow these simple steps

1. Go to Settings

2. Tap on General

3. Tap on Reset

4. Tap on Reset All Settings

What this effectively does is to reset some of your Settings to factory default. It’s not a complete removal of settings. It removes all of your preferences for Wi-Fi, Bluetooth, Do No Disturb, Notifications, General, Sounds, Brightness & Wallpaper and Privacy. It doesn’t affect your data. All of your email accounts will remain intact, as well as any SMS text or iMessages.

 Cheers, Tom 😉

I don't know why your speaker is crackling. I have seen this happen to other people and resetting the iPad fixed the problem for them. It might not work for you, but it doesn't hurt anything. It's like rebooting your computer, when you reset your iPad.

If resetting doesn't fix the problem, best thing to do is probably to book a Genius Bar appointment and bring it in to the Apple store for them to have a look.