Check application if is running

Not sure that I understand. Which application are you checking?

I try to explain the scenario:

When start my app, sets the audio settings (mode normal, max level volume ecc..) to enable better management of the voice recognition.
When i close the application with back button, resets the audio settings

The problem is how to reset settings if the user close application with home button.
I thought of a service (which starts when the application starts) that every second checks if the application is active or not. If not (IsPause(MainActivity)) resets the audio settings.
As mentioned before, the method IsPause is not reliable when in action the voice recognition

I would like to know if there another way to check if application is active or not

The problem is that in Android there isn't really a point where your application reaches its end (unless you create an "Exit" button).

The simplest solution is to set the audio settings in Activity_Resume and reset them in Activity_Pause. If however you also need the custom settings when the voice recognition dialog is visible then you should use the service and check whether the activity is paused after 30 seconds.

This may help:

sub CheckPackage(Package as string)
Dim sb As StringBuilder
sb.Initialize
Phone.Shell("ps", Null, sb, Null)
Dim m As Matcher
m = Regex.Matcher2("^[^ ]*\s+(\d+) .*" & Package, Regex.MULTILINE, sb.ToString)
If m.Find Then
Log(Package & " is running")
Return True
Else
Log(Package & " is NOT running")
Return False
End If
end sub

The above code will not help in this case. The process is running for sure as the service is part of the process.