Disable notification sounds but keep SMS Sounds Device: Galaxy Ace Duos 6802

I want to to turn off all the notification sounds, but keep the SMS sounds when I get SMS, WhatsApp messages, Skype messages, etc. It is very frustrating having to hear my SMS ringtone everytime my phone is updating an app, or when the battery is fully charged. However, I don't want to miss out on any Whatsapp messages I get.
A partial solution is to create a silent notification sound and use it as default, and then set custom notification sounds in each of the apps you use, assuming that the apps allow you to choose your notification sound. Most stock SMS apps and WhatsApp allow this, but the latest version of Skype does not.