Thu. Aug 18th, 2022

So you’ve just purchased a new pair of wireless headphones. If they were Apple’s AirPods, you forked out $229, so you’d expect them to work close to flawlessly.

Except it turns out AirPods, like other wireless headsets, are susceptible to signal congestion, which can lead to dropouts caused by a build-up of other nearby devices that operate on the same frequency band.

In the case of wireless headsets, this is often caused by other devices operating on the same busy 2.4GHz frequency as the headphones; a frequency used by some cordless phones, other Bluetooth devices, Wi-Fi access points, baby monitors, microwave ovens, wireless microphones, and RFID theft-prevention technology in retail stores.

Even some traffic lights in NSW have been known to use Bluetooth as part of a trial to analyze signals moving through the road network to count traffic volume, measure travel times and provide detailed information on traffic movements. So if you’re near a traffic light, this could potentially be causing you issues too, and is apparently something Apple’s Genius Bar staff have acknowledged is an issue.

A spokesperson for Roads and Maritime Services, which operates NSW’s traffic lights, said “the use of wireless equipment in traffic infrastructure is limited”, without revealing further detail. But they said the trial to measure traffic flow using Bluetooth receivers had ended, and there were “no receivers currently in use”. Apple declined to comment for this story.

Further, phones can only make a limited number of Bluetooth connections at once, so if you’re using a fitness tracker, wireless headphones and a smartwatch, issues will be more obvious.

“There are literally millions of devices that operate in that [2.4GHz] spectrum across Australia,” explains Mark Loney, executive manager of the operations branch at the Australian Communications and Media Authority, which regulates spectrum, “and you will get to some point where you will find a device that is just going to get beyond its operating limit, it won’t be able to receive a signal [due to] all the other activity going on in the area.”

Apple's AirPods aren't cheap: they cost $229.

Apple’s AirPods aren’t cheap: they cost $229. CC: BLOOMBERG

In recent testing in Sydney, we uncovered one particularly problematic spot where a journalist’s wireless headphones dropped out almost every time he approached traffic lights on the corner of College and Oxford Street in Surry Hills, just outside Sydney’s CBD. The journalist observed various fixed-wireless equipment in the area’s vicinity and hundreds of Bluetooth and Wi-Fi signals, which the ACMA says could be why the dropouts are occurring.

RMS said it did not operate any wireless equipment at the intersection of College and Oxford streets, however, this doesn’t rule out other authorities’ equipment causing congestion.

“It is certainly a possibility that there may be facilities in that vicinity — on the poles or in the general region — that are using the 2.4GHz [frequency and causing congestion],” says James Cameron, an authority member at the ACMA. “If you are in a CBD environment where you have got a lot of shops, commercial offices, and apartments plus street-side infrastructure there is going to be very intense use.”

But it’s not only fixed devices that cause dropouts. People who own “key finding” devices, such as those sold by Tile, can also cause problems.

Operating on the 2.4GHz spectrum, Tiles are often attached to keys or placed in wallets and regularly send a signal of their position to their owner’s smartphone. In the Pyrmont region alone in Sydney, Tile’s app shows there are 12,177 Tile users.

After Tile received reports of headphone dropouts from its users, it released a feature designed to ease congestion problems that users need to go into their settings to turn on. It limits the number of times its devices connect to users’ phones.

“When Bluetooth bandwidth is being used up by smart speakers, fitness trackers, headphones, music streaming, etc., the connection to one or more of your Bluetooth devices can falter or drop,” a Tile spokesperson says. Other factors can also affect Bluetooth bandwidth, such as humidity and the distance between you and the transmitter, the spokesperson said.

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