private lateinit var audioManager: AudioManager ... audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager val targetVolume = 0 audioManager.setStreamVolume(AudioManager.STREAM_ALARM, targetVolume, AudioManager.FLAG_PLAY_SOUND) audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, targetVolume, AudioManager.FLAG_PLAY_SOUND) audioManager.setStreamVolume(AudioManager.STREAM_SYSTE..