I looked up in the net, it was suggested to set the additionalFlags option of AndroidNotificationDetails to have a value of 4.

This is what I did

AndroidNotificationDetails(
      'notif',
      'notif',
      'Notification',
      icon: '@mipmap/launcher',
      priority: Priority.high,
      sound: RawResourceAndroidNotificationSound('notif'),
      largeIcon: DrawableResourceAndroidBitmap('@mipmap/launcher'),
      additionalFlags: Int32List.fromList(<int>[4]),
      importance: Importance.max,
      playSound: true,
    );

But the moment I swipe down to see the list of notifications, the sound stops playing. I want the sound to keep playing, unless and until I tap on that particular notification (and not merely swipe down to see the list of notifications)?