NotificationChannel always make sound in Android 8.0

I have upgraded target build version to 27 so need to implement notification channel. I'm starting a foreground service which will show a notification when started. With notification channel it's working as expected but it's always make sound. Changing the notification priority doesn't have any effect.

if(Build.VERSION.SDK_INT >= 26) {
    NotificationChannel notificationChannel = new NotificationChannel(CHANNEL_ID,
            CHANNEL_NAME, NotificationManager.IMPORTANCE_LOW);
    mNotificationManager.createNotificationChannel(notificationChannel);
    notification = new Notification.Builder(this,CHANNEL_ID)
            .setContentTitle("My App")
            .setContentText(status)
            .setSmallIcon(R.drawable.ic_stat_notify)
            .setContentIntent(pendingIntent)
            .build();
}

I have checked IMPORTANCE_MIN, IMPORTANCE_DEFAULT and IMPORTANCE_LOW, all are making sound