Bose investigation concludes QC35 firmware update didn’t break noise cancellation

Bose is bringing an end to the long-running saga of complaints regarding noise cancellation issues with its Quiet Comfort 35 and Quiet Comfort 35 II Bluetooth headphones. After spending months looking into reports of reduced NC performance — something many customers have blamed on firmware updates — Bose has concluded that firmware isn’t responsible for the perceived drop in noise cancellation effectiveness. But it’s going to let QC35 owners downgrade back to older firmware if they want to, which is an option that the company had previously supported, but later pulled amid all this controversy.

As noted by Gizmodo, Bose published a long, in-depth forum post about its findings on Thursday. “When we launched QC35 I and II, we set stringent specifications for noise cancelling performance,” the company wrote in its report. “Through all of our investigation and testing, we’re confident that firmware 4.5.2 did not affect the noise cancelling feature.”

The company conducted extensive lab testing and went so far as to visit some customers at home to observe them using the QC35 and QC35II headphones. “This robust evaluation of customer-returned units did not reveal any issues with noise cancellation performance, and Bose was not able to replicate the concerns of our customers,” the report says.

Image: Bose

But since there was still a disconnect between customer feedback and its own findings, the company wasn’t satisfied to end the investigation there. So it went further and sought out independent testing through “a third-party acoustics test laboratory.” Again, the updated 4.5.2 firmware showed no signs of being the culprit behind degraded noise cancellation.

So what’s the problem, then? There’s got to be something going on that created this chorus of complaints, right? Well, Bose has an explanation. In the few small cases where it did find a measurable difference in noise canceling quality, the company says the ear cups weren’t fully snapped on; Bose says missing even one of the 10 tabs can make a difference. Third-party ear cushions were also found to “negatively impact passive reduction performance” and put the headphones out of spec, and Bose also noticed that some units from customers had mechanical damage — likely from everyday wear and tear.

“Our full engineering analysis determined that the degradation in all cases was the result of hardware related issues with ear cushions, aftermarket parts, or mechanical integrity. Once again, the firmware update 4.5.2 was not found to be the cause of any degradation in overall noise reduction performance.”

In response to all of this, Bose is updating its testing procedures, improving its firmware update website, and (temporarily) giving customers the option to downgrade if they so choose — even while insisting that firmware was never the problem. QC35II owners can downgrade to 4.3.6, and the original QC35 can go back to 2.5.5. “If you wish to take advantage of this downgrade option, we advise you to do so as soon as possible,” Bose said, and the company said it encourages all customers to remain up to date on the latest firmware. It also made the above video for troubleshooting noise cancellation problems.

Take it all in, and I think this is a pretty commendable job from Bose in trying to hunt down whatever problem has been frustrating people. The company took a long time to address the initial buildup of complaints, but it’s hard to argue that Bose didn’t put in some serious work here. To that end, Bose has posted a forum thread where customers can discuss the latest report. Some are appreciative of the company’s effort, but others still think Bose has missed the mark and say the reduced noise cancellation issue remains unresolved.

The overall takeaway is this: if your QC35 or QC35II are working well, maybe just try to keep them on whatever firmware they’re running for as long as possible if you want to avoid this headache.