Amazon Prime Day - Bose QC25 on sale $125

Thank you! I would have missed this if you had not posted.

Thanks for the alert! Spousal Unit loves his and I've got a pair for myself now. The AAA battery ones are actually better because Bose makes proprietary battery replacement expensive enough you just want to buy a new set.

Missed the saled. It's at $200 now. Thanks for sharing though.

it uses a replaceable AAA battery.

If the headphones are wired, why is a battery needed?

I assume the battery is used to power the active noise cancellation electronics. The wired connection is for the sound signal. So these don’t have Bluetooth connectivity.

I assume the battery is used to power the active noise cancellation
electronics. The wired connection is for the sound signal.

Thanks. As you can tell, I am not familiar with the particulars of noise cancellation. What exactly do you hear that cancels out the noise and thus requires a battery to emit?

Amateur explanation: you hear nothing but your music or audiobook, but the part that requires a battery generates a sound that cancels out the exterior noise of, say, the airplane engine. An engineer could explain more scientifically, but this is how I understand the process. I just know it’s a wonderful thing to have on a long-haul flight.

sound (or noise) is in the shape of a wave, both above and below a centre line. If a device can hear exactly what wave is being emitted it can mimic the noise but make the wave upside down. So the up bits of the sound are cancelled by the down bits of the mimic, and the same for the down bits of the wave cancelled by the up bits of the mimic.

It takes some decent circuitry to achieve all that in real time and not delete the sounds you want to hear.

I wanted to make it sound as simple as I could, but it is actually quite complicated.

The technology has come on by leaps and bounds over the years. Back in the days when people still used quill pens on papyrus and I was but a callow youth I worked for an electronics company doing work for the US Navy in exactly this technology. This was at the early days of transistors and chips were barely a gleam in some engineer's eye. Imagine trying to devise circuits like this using vacuum tubes.

Thanks Nigel. Your explanation especially about the waves does help.