Hello everyone!
I’m wondering here what is the why track whether the sound on my device is on/off?
The thing is that when I use  

wav_player_start

my sound’s volume changes only after pressing hardware buttons. If I want to set my phone to “mute” or “vibrate” modes from the top panel the sound is still played! 
P.S.: I use 

SOUND_TYPE_RINGTONE

Thanks for helping!