Anyone looking forward to a cross country (or cross ocean) trip in a plane
where passengers can use their cellphones? Noise cancelling headphones
anyone?
If you have not personally tried these you might be surprised with
this.
Unfortunately in my experience, using three different brands of noise
cancelling headphones over the last 15 years, while they do a
surprisingly good job of whacking low frequency roar and rumble of
engines and road noise, this actually lets the conversations that you
were not previously able to hear come through loud and clear now.
Flip
the switch off and the roaring grumble of the city bus is all you can
hear, flip it on and now two dozen conversations, half on cellphones,
loud and clear is what you get to listen to.
I've asked a number of times if this is just because of the compute
power or battery life or the quality of the microphone limiting the
upper frequency that is effectively cancelled, or if there is really
deeper physics that says it would be exponentially harder for every
higher octave. I tried reading the Handbook of Noise Cancellation and
couldn't get an answer from that either.
I've never gotten what seemed like a really convincing explanation,
but
I have gotten some silly ones. The sales kid at the Bose store, who
was
1/3 my age, told me I would be putting my life at risk if they
cancelled
the speech so this would never be done, strictly them saving my
life.
But I have not tried the $500 Bose small plane pilot noise cancelling
headset on the bus, they didn't want to loan me a set for the
afternoon,
and you don't get to see those at your mall Bose store. Those are
supposedly playing at a completely different level from the consumer
grade Bose and Sharper Image and Philips and two other brands, one of
which I started using over 15 years ago and are now flakey. The
Philips
HN050 were particularly poor compared to others in my opinion, but
they
were cheap when closed out. They claim only 10 dB reduction between
100
and 1500 Hz. If you didn't have experience with noise cancellation I
doubt you would even notice this.
If someone finds a brand that really does cut 40 dB from 20 Hz to 6000
Hz or more and is plausibly priced let me know and I'll buy a pair.