2

I am looking at active noise cancellation system for buses. I have found systems that have been developed by car manufacturers, but I am looking especially for systems designed by coach and city bus manufacturers, and unfortunately there is nothing on the internet about this issue. Can you give me some links or information about using this technology on buses.

Grüße.

  • @MooseLucifer Unless I misread the question, the OP is referring to the Lexus/Inifiniti style systems that employ the car stereo to provide some of this effect in the cabin. I'm pretty sure we are talking about a "house" system built into the bus, not wearing a set of headphones. I made a clear distinction in my answer. – SteveRacer Aug 29 '16 at 23:09
  • @SteveRacer OOHHHHHhhhhh. That makes much more sense and is totally on topic. I was not aware of said systems. I'd retract my close vote if you or OP edited the question to include a link or description of the Lexus/Infiniti systems. – MooseLucifer Aug 29 '16 at 23:12
  • @MooseLucifer done. This comment will self destruct within 24 hours. – SteveRacer Aug 29 '16 at 23:23
1

First, I am assuming you mean an embedded system like Cars Go Quiet, not a set of headphones optimised for a city bus. The latter would not be on topic here.

There's great information (albeit somewhat technical) contained in "Is active noise cancellation useful in vehicles" which may shed [eventually] the answer you are looking for, but I will try to explain the major caveats in simple terms here:

The problem is maintaining the correct anti phase relationship between what is likely the entire vehicle as a sounding board, and one or more "point source" generators (speakers).

The cancellation effect can even be done with light (lasers) MIT Destructive Interference

HOWEVER, there are some very key criteria. The energy must by culminated, focused, single-sourced, not combined with reflected waves, and ultimately maintain strict phase stability in the desired environment. This is almost never true with real light, and only marginally the case with a carefully benched and controlled split-mirror laser beam. Sound is a lot slower and simpler, and more stable as well. The multi-source and multi-phase issues are still a problem, and exponentiate depending on the volume of the space you want to control noise.

On a set of headphones, this is easily achieved, with only the space in the ear canal that needs to be carefully regulated.

On a car, this can be done to some extent, but will be most effective in the lower "exhaust rumble" frequencies.

On a bus, there is likely too much volume to address the multi-phase and multi-directional sound, as well as expect a single point source to address this volume effectively front-to-back.

The only simple solution for a bus is to wear a set of headphones.

Not the answer you're looking for? Browse other questions tagged or ask your own question.