Today Apple was granted a patent titled "Ultrasonic touch detection through display" Apple's granted patent relates to system architectures, apparatus and methods for acoustic touch detection and exemplary applications of the system architectures, apparatus and methods. The technology will allow touch commands on an iDevice under water and more. 

 Apple notes in their patent filing that the position of an object touching a surface can be determined using time of flight (TOF) bounding box techniques, acoustic image reconstruction techniques, acoustic tomography techniques, attenuation of reflections from an array of barriers, or a two-dimensional piezoelectric receiving array, for example.

Acoustic touch sensing can utilize transducers, such as piezoelectric transducers, to transmit ultrasonic waves along a surface and/or through the thickness of an electronic device to the surface.

As the ultrasonic wave propagates, one or more objects (e.g., fingers, styli – Apple Pencil) in contact with the surface can interact with the transmitted wave causing attenuation, redirection and/or reflection of at least a portion of the transmitted wave.

In some examples, an acoustic touch sensing system can be configured to be insensitive to contact on the device surface by water, and thus acoustic touch sensing can be used for touch sensing in devices that are likely to become wet or fully submerged in water.

Apple's patent FIG. 2 below illustrates an exemplary block diagram of an electronic device including an acoustic touch sensing system; FIG. 4 illustrates an exemplary acoustic touch sensing system stack-up

Apple's granted patent 10,802,651 that was published today by the US Patent and Trademark Office.

This theme of underwater iPhone technology is starting to become a trend.  On September 22, 2020 Patently Apple posted a report titled "Apple Wins a Patent for a future iPhone with Under Water Imaging Capabilities in up to 60 Foot Depths."