Electronics Repair Questions? Ask an Electronics Technician
You are likely hearing that sound when you get a notification(such as an email or a text message).
Most likely, it is for a text message. To change the sound for a text message, then open the messaging app, and tap the 'menu' button(3 dots). Then press settings. Then go to Notifications and then sound. Now you can select another tone for new text messages.
If the notification isn't from a text message, then please let me know the following information: When you hear that sound, do you know exactly what type of notification you are getting? You should see the icons at the top, and you should be able to swipe down from the top to see your notifications.
Hello. Did you still need any help with this?