Google has started an investigation into the "ticking" sound that's affecting certain Pixel 2 units. The issue recently came to light as owners of the smaller second-gen Pixel device reported hearing clicking and high-pitch frequency sounds during voice calls.
A community manager at the official Pixel forum who goes by the name of "Orrin" said that Google is looking into the issue and offered a temporary fix:
Our Pixel 2 review unit also suffers from this problem, so we can confirm that disabling NFC truly works. Needless to say, when NFC is turned off, connected services like Android Pay and Trigger also won't work, but we suspect that Google will soon find a fix for the issue. The iPhone 8 also suffered from a similar ailment at launch, but Apple quickly resolved the problem with a software update.