iPhone 16 Plus: Unexplained train whistle and haptics

• Another place to check is at Settings > Notifications > Mail > Custom Notifications (bottom of page). Do any of your Accounts listed there show Sounds under the name? If so, tap on that account and see if the sound used is Choo Choo. That will override any default sound or setting that you have for Mail notifications.

• Do you have the Life360 app? That will play a sound when a member of the plan arrives or leaves a location. Similarly the Verizon Family app also has a feature that works the same way. While at times you said it appears random no matter what you are doing, but does it seem to happen on your phone when your partner leaves a location. That could happen when you leave together or appear random on your phone when it is just your partner leaving a location. That may indicate it is one of those types of apps used to keep track of members.

• I assume you also went through the list of apps that show Sound at Settings > Notifications. You can have an app that is only set to play a sound without any banner on your screen. Mail is one exception where it may not list Sound, but as seen in the first point, you can still have a Custom Notification sound.

It may be that you have a Shortcut that had been added either accidentally or someone that knows your Passcode is pulling a prank on you. Social Media sites have Shortcuts that you can download and you may have inadvertently downloaded one without knowing what it did. It is easy to create a Shortcut that plays a sound either at random times or when you leave a location.

Open the Shortcuts app and tap All Shortcuts and you will see a list of the Shortcuts on the top of the Library screen. The ones listed first are on your device and may be active. Below that are Shortcuts that an app can provide when creating your own Shortcuts. It is not necessary to have any Shortcuts on the top of that screen for any operation of your phone, although there are some Starter Shortcuts that gives you some examples of how they can be used.

Could it be this --> https://discussions.apple.com/thread/253557808?sortBy=oldest_first

Expressing or conveying auditory experiences effectively through these forums may be challenging. The underlying sound issue on your iPhone cannot be accurately diagnosed from a YouTube link. Factors such as your iPhone's specific sound settings, visual defects, and potential hardware problems cannot be assessed through this method. For more personalized and in-depth assistance, I recommend securing a Genius Bar Reservation and exploring the various support options provided by Apple.

Get a Genius Bar Reservation and Apple Support Options - Apple

When you encounter issues with your Apple devices, the Genius Bar at Apple Retail Stores is the go-to place for expert assistance. The Genius Bar is staffed by knowledgeable Apple employees, often referred to as "Geniuses," who can diagnose and resolve a wide range of hardware and software-related problems. To ensure personalized attention and a convenient visit, Apple provides the option to schedule a Genius Bar Reservation.

Contact Genius Bar.

Manage Reservations - My Reservations - Apple

I am having exactly the same problem with an iPhone 16e. I have used various suggestions obtained from AI platforms. Nothing has worked, but apparently this is not an uncommon problem. I would think Apple would be all over this? The sound is so distinctive and it’s clearly related to motion, but there are no visual messages or warnings. How hard can this be for an engineer to figure this out? I bet there have already been multiple “genius bar“ queries about this?

51Alan

I continue to have the same problem. Somewhere, someone, suggested it might be related to the wireless carrier. I am on a Verizon. May I ask, what carrier you are using?