If you noticed a change in the sound quality coming from your AirPods Pro, it’s probably due to a firmware update released in December. After many users speculated that the update was to blame, testing done by RTINGS.com has confirmed this to be the case.
The site had already reviewed Apple’s AirPods Pro before the new firmware was released, but ran the same tests on the earbuds again after receiving last month’s update. When comparing the results, the site found “minor changes” to the sound reproduction of the AirPods Pro---some of them positive, and some negative. RTINGS posted these discoveries in a series of updates to its original review page on 1/10/20.
(Note: RTINGS calls it Firmware 2C45 but it’s actually 2C54, whoops.)
Bad news first: If your AirPods Pro have been updated to firmware 2C54 (from 2B588), you’ll be dealing with worse noise isolation performance in the bass range, which is to say that when active noise cancellation (ANC) is enabled, the earbuds won’t be as good at blocking noises such as the engine of a bus or plane. RTINGS also recorded a slight reduction in mid-range sounds and a very slight reduction in treble accuracy.
On the flip side, updating to firmware 2C54 brings a “significantly better” frequency response consistency and bass accuracy. However, likely due to the aforementioned noise canceling issues, it’s also worth noting that Apple pulled firmware 2C54 so your AirPods Pro might not have been updated. However, if they have been updated, then it seems you’re stuck with the borked firmware until Apple releases another update.
You can check what firmware your AirPods Pro are running by connecting them to an iOS device and then navigating to Settings > General > About > AirPods > Firmware Version. The old firmware: 2B588; the new firmware: 2C54.
Here's to hoping for a quick fix.