After updating audio setting in my lumia 520, when I opened it there was a flash of equalizer and then it disappears.
From then onwards whenever I opened it the same scenario is repeated.
Please help me...
As far as I'm aware, the Lumia 520 doesn't have an equalizer. It's likely just a glitch that it's showing up in the settings. Thus the reason why it crashes. And by the way, this isn't the right place for this post. This should be in the Nokia Lumia 520 forum.
The lack of equalizer and Dolby in L520 is not a hardware issue. Lumia 620 has equalizer. Both Lumia 520 and 620 have the same audio codec - WCD9304 and Class-D Audio Amplifier with Gain Select - TPA2012. The same hardware is used even in Galaxy S4. Nokia just blocked(or just didn't add equalizer drivers L520's firmware) in software.
There's already a built-in equalizer in Lumia's music app, so don't have to develop anything. It's simply a firmware issue. When firmware detects your phone as L520 it disables equalizer. You can either make your phone be recognized as L620 or just decompile audio firmware and add support for Lumia 520. Your warranty will be void when you do so. Reverse engineering is also prohibited by the EULA.
When firmware detects your phone as L520 it disables equalizer. You can either make your phone be recognized as L620 or just decompile audio firmware and add support for Lumia 520.