billvs
New Head-Fier
- Joined
- Feb 21, 2011
- Posts
- 1
- Likes
- 0
This is a bit off-topic for this group, but it seems that there are some knowledgable folks here. So, is it possible to use head-phone style noise cancellation circuitry connected to loudspeakers to cancel a point source of 60Hz transformer hum?
I live across a lake from a very large transformer, and it has a very loud 60Hz hum. The folks who built it just put up a theoritically sound reducing wall, but it is ineffectual.
In theory, I should be able to take the guts of a sound cancelling headphone, (like http://gilmore2.chem.northwestern.edu/projects/noise_prj.htm ) connect it to an amplifier and do larger-scale sound cancellations. For ideal operation, the sound would have to come from a point source, and the mic and speaker would have to be colocated with the sound source.
However, the transformer in question is about 30ft x 20ft. The wavelenght of the 60Hz sound is about 12ft, right? So, the source is not a point source. Even if it were a point source, I do not think I could get the county water department (who own the transformer) to mount the gear on their site.
So, my plan B would be to try to do noise cancelation of one or more areas on my property. There is very little multipath, and the sound is largely from a single direction - across the lake. Would putting a mic, processor (tuned to 60Hz for simplicity) and speaker at the corner of my deck work? At the corner of my property? Based on the 12ft wavelenght, I should be able to protect an area of a few multiples of 10 ft, right?
My EE degreee is about 30 years old, so my brain hurts when I think about this stuff.
Thanks in advance
Bill VerSteeg
I live across a lake from a very large transformer, and it has a very loud 60Hz hum. The folks who built it just put up a theoritically sound reducing wall, but it is ineffectual.
In theory, I should be able to take the guts of a sound cancelling headphone, (like http://gilmore2.chem.northwestern.edu/projects/noise_prj.htm ) connect it to an amplifier and do larger-scale sound cancellations. For ideal operation, the sound would have to come from a point source, and the mic and speaker would have to be colocated with the sound source.
However, the transformer in question is about 30ft x 20ft. The wavelenght of the 60Hz sound is about 12ft, right? So, the source is not a point source. Even if it were a point source, I do not think I could get the county water department (who own the transformer) to mount the gear on their site.
So, my plan B would be to try to do noise cancelation of one or more areas on my property. There is very little multipath, and the sound is largely from a single direction - across the lake. Would putting a mic, processor (tuned to 60Hz for simplicity) and speaker at the corner of my deck work? At the corner of my property? Based on the 12ft wavelenght, I should be able to protect an area of a few multiples of 10 ft, right?
My EE degreee is about 30 years old, so my brain hurts when I think about this stuff.
Thanks in advance
Bill VerSteeg