Future Development
and advice for the young and optimistic sound cancellers of today

Keep your circuit on the breadboard for most if not all of the testing. Small things can easily get mixed up on a circuit board, and it's best to have everything laid out and easy to measure while you are still testing.

Use a nice pair of headphones for the user and a sacrifice a cheap pair for the mics.

Research the speed of sound through whatever material makes up your user's headphones. Compare it to the speed of electricity-- it will be painfully slower. Think about what you could do to offset this.

Bring more than one CD into the lab when you're preparing to work on the project. And if you're looking for suggestions, try "Magnetic Fields" or "Stereolab." (these suggestions are the responsibility of Laura and perhaps no one else in the group.)

Start by seeing what your headphones do with generated low-frequency sine waves.

If you are able to get a good response for low-frequency tones, they will get even better if you add a good low-pass filter. We added an easy first-order RC filter but you could get fancy and do a second-order or higher or a different kind of filter.

or, you could go for the more ambitious feat of diminishing higher frequencies. This will take a lot of precision dealing with the phases of both the original signal and the inverted signal.

for ambient noise cancellation that does not cancel directional noise, you could subtract the signals from each mic and omit that from the cancellation signal sent to the speaker. This means that signals that differ in amplitude from one ear to the other are not cancelled... cool.

Don't expect to cancel out your annoying partners' babbling. (if you are able to do it, though, contact us.

the studs