What’s behind the mystery of high-pitched noises emitted by Google’s new Pixel 2?

People who have bought Google’s new smartphones are having their calls interrupted by mysterious “highpitched” sounds.

The Pixel 2 and Pixel 2 XL only went on sale on 19 October—the Pixel 2 XL will start shipping on 15 November in the UK—but have already sparked a huge number of complaints.

These include potentially serious screen issues, unreliable Bluetooth connectivity and strange noises during calls.

Users have taken to online support forums to bring attention to the sounds, which are being described as “clicking”, “whirling” or “squealing” noises.

They say the Pixel 2 clicks when NFC is on, and emits a high-pitched sound during calls. Several methods for fixing the issue are being suggested by users, including switching off NFC, Bluetooth and Wi-Fi.

The Pixel 2 and Pixel 2 XL are the lynchpin of Google’s efforts to take on Apple Inc’s iPhone directly.

Google said on Sunday it is investigating whether graphics are burning into the display of the Pixel 2 XL, following a report on the Android Central blog detailing the issue after a week of use.

Burn-in, which usually becomes a problem only after several months of activity, can make it difficult to see information on the display.

Google likely would need to halt production if there is a problem, said Ryan Reith, a mobile device analyst at research firm IDC.

“We take all reports of issues very seriously, and our engineers investigate quickly,” Mario Queiroz, Google’s vice president for Pixel product management, said in an emailed statement to Reuters. “We will provide updates as soon as we have conclusive data.”

The investigation follows Google’s acknowledgement that it may introduce new software to respond to users’ concern about a blue tint to the Pixel 2 XL’s 6-inch screen. The device incorporates new OLED display technology, which Google described as offering “a more natural and accurate rendition of colors.”

On Friday, the company vowed to reimburse an undisclosed number of people who were charged $30 extra for the Pixel 2 by a Verizon Wireless reseller operating at Google pop-up stores in the United States. The surcharge “was an error,” Google said in its apology.

Prior complaints l ed Google to drop the price of an adapter used to connect headphones to £9 from £20, matching the price of a comparable iPhone adapter.

Google also sent emails over the weekend to buyers advising that delivery of their Pixel 2 may be delayed as much as one month, to late November, according to the Android Police news blog and users’ postings on Reddit forums. Customers said Google offered a free smartphone case, which otherwise starts at $ 40. Google did not immediately comment.

Google made a significant bet on the smartphone business last month, agreeing to acquire an HTC Corp hardware development team for $1.1 billion.

Shares of Google fell 1.9 percent to $985.54 at Monday’s close. THE INDEPENDENT