Thanks for reading, and for the great question!
I do call testing for any headphone that supports it in a moderately noisy cafe. Unless there’s a major issue for the person on the other side, I don’t say much about it because it’s not usually the feature that people want me to focus on. But let’s dive in for these two a little deeper!
Only Bose officially touts that they use the same noise-cancelling algorithm on the mic that they use for your audio, and it does indeed cancel out some background noise in a similar fashion to the playback mode. I can confirm that the poor soul I talk to who helps me test these things had an easier time hearing me on the QC35’s, though the Sony’s worked okay. I’m not sure that Sony does any specific noise-cancelling on their mic feed, and if they do…they don’t mention it.
With the Bose model, you also get automatic built-in sidetone, which makes it easier to hear yourself…though if you’re in a very loud room, it might actually hinder your ability to hear the person you’re talking to, because the ANC is lessened and you’ll get a fair bit of that background noise pumped into your headset. There’s no way to turn the sidetone off, either. A strange dilemma then, eh?
On call quality and background noise reduction alone, considering nothing else, the Bose set is better.
Also of note: Both headphones only support calls in Wireless Bluetooth Mode. So if you’re looking to make calls on the cable, it’s a no go with the included wires. On the Sony set, you can buy a third party cable that includes a built-in mic…but then you’d be right back to something comparable to your mic experience with the QC15's.
I hope that helps you out! Bose and most of their retail partners offer a decent return policy, so if you try out the QC35 and hate it you should be able to return it. If the server room noise is above a certain low frequency level, any ANC algorithm is going to have a tough time with it, and microphones in general love silent environments for picking up voices. If that sounds like me hedging, it’s because I am! :)