[HardySpicer]

On Jan 20, 5:20*pm, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.


hardy