Small Ship Noise Cancelling Systems... Do they exist commercially?

Bertramdriver

Bertramdriver

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From the research I've done it almost impossible to find a boat noise cancelling system. I thought I was making progress with an Israeli company who had a small area 2msq "cone of silence" package that they had developed for the wheelhouse of Israeli Navy gunboats, but as soon as I got serious they killed the contact. It's a shame. Their system was laptop based software, microphones and a couple of speakers all for a couple of £ grand. Since they pulled out I haven't found any other source. Anybody know who else is around to contact? If not, does anyone out there fancy developing one?
 
I don't know about the Israeli system, but it would be extremely difficult to create a noise cancelling system that didn't require headphones. They work by creating a copy of the sound to be cancelled, inverting the phase, and putting it through a speaker. The sound entering the ear must be of equal amplitude and 180 degrees out of phase with the original. Obviously, the closer to the ear the anti-phase sound is created, the closer will (can) be the phase difference to 180 degrees. I can't imagine how it could work without headphones. You may as well buy some noise cancelling headphones.
 
The value of the Israeli system is that it is possible to select the frequencies to be cancelled out. Eg you can select the frequencies associated with the boat exhaust note which are then effectively countered, but all other frequencies such as stereos and VHF are unaffected.
It works by the microphones picking up all ambient sound and then the software breaking down the noise and sorting each frequency range into a distinct pattern, like a hifi frequency analyser or recording mixing deck, which can then be countered through strategically placed speakers. Within the cone of silence created the engine exhaust noise is dramatically reduced but you can still hear a seabird calling.
That's the theory anyway and the Israeli guy assured me that it has a really significant effect on their patrol boats, allowing the helmsman to listen for other remote engine noises around the boat. Guess I ran into their "National Security" issues.
As my boat has a open back wheel house and the aft deck seating is over the exhausts it seemed like a great way to control the unwanted noise and allow a conversation between both areas. If I was a few years younger, and richer, I would have a go at this one myself.
 
From what I remember of this, from many years ago: I might well not be up to date:
as already said, it's much easier to cancel noise in the small volume of headphones, and there are many commercial and leisure systems that do this.
If you want to reduce noise, do the obvious things first. For instance. If exhaust noise is a problem (first thought: is it exhaust noise? there are many ways that engines can produce noise) then fit more efficient silencers.
You may find that some of the noise is structure borne, and you can combat this.
If the engine noise is echoing around the wheel house, then there are ways of reducing this using conventional sound deadening.
Really, the place to put sound reduction measures in place is the drawing board. Once the boat is built, your options are more limited.
Active noise reduction over the large volume of a wheel house is going to be expensive and possibly (depending largely on exactly what you are trying to do) not as effective as you might have hoped. And of course, if it's a one off then the development costs will be all yours. Start with more conventional methods, which might well be enough.

And: what works in one boat might not be the optimum solution in another.

Maybe some people like to hear the engine. Getting the right engine noise is a part of sports car design.
 
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Hi Bertram, another tack, for more available software at least, might be to look into intelligent eavesdropping systems. For example, I want to hear the conversation of a couple of spies in the embassy, by pointing a directional microphone at their open office window from across the street. However it is Knightsbridge and the traffic noise is dominant, their voices are totally lost amongst the hooting cabs and roaring buses.
However, with my clever software, I can leave the mike hanging out the window all morning and the software will learn all the street noises and wipe them from the recording, either by frequency (a standard black cab horn for example) or by inverting the waveform (an accelerating motorbike for example), allowing me to hear the betrayal of the battleship blueprints.
Perhaps you were trying a bit too hard with the IDF? By the way, have you noticed the bagel delivery van with lots of aerials in your street ;)
 
I have seen a cabin noise cancelling system in a small business prop jet. Apparently very successful. Google for aircraft noise cancelling. I am sure they will sell you a system. Probably pricey though. I would think if you were seated in the centre of the weel house with speakers either side it could work well. Indeed if you got noise cancelling headphones and add 2 amplifiers in lieu of phone speakers then to 2 larger speakers it should work OK. Room for experiment.
However as said I have always thought there is no excuse for noisy engines in boats. Insulation and water cooled exhausts work well. I hear from home some boats incredibly loud exhaust while most are very quiet.(just like cars) do some people get high on exhaust noise? good luck olewill
 
Bertramdriver said:
From the research I've done it almost impossible to find a boat noise cancelling system. I thought I was making progress with an Israeli company who had a small area 2msq "cone of silence" package that they had developed for the wheelhouse of Israeli Navy gunboats, but as soon as I got serious they killed the contact. It's a shame. Their system was laptop based software, microphones and a couple of speakers all for a couple of £ grand. Since they pulled out I haven't found any other source. Anybody know who else is around to contact? If not, does anyone out there fancy developing one?
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Why would you want to filter out sound? It tells you all sorts of things.
 
Bertramdriver said:
From the research I've done it almost impossible to find a boat noise cancelling system. I thought I was making progress with an Israeli company who had a small area 2msq "cone of silence" package that they had developed for the wheelhouse of Israeli Navy gunboats, but as soon as I got serious they killed the contact. It's a shame. Their system was laptop based software, microphones and a couple of speakers all for a couple of £ grand. Since they pulled out I haven't found any other source. Anybody know who else is around to contact? If not, does anyone out there fancy developing one?
Click to expand...


They killed the contact?
Would have been easier just to say "No we don't sell it to you." :D
 
http://www.silentium.com. I thought I was making progress with their tech guys and then no reply to my mail. Annoying.
Most of the points in the thread are well made but I want the option. Yes I enjoy the purr of the DD's but after a few hours it can be wearing. I don't like the idea of headphones because I can't hear the VHF and what's going on behind me. A switch on/off nose reduction system tuned into the exhaust note seems the perfect solution.
I suppose I'll have to do with sitting on the foredeck and driving by remote control.
 
I find it so depressing on this forum that people who have nothing to say resort to abuse and mockery, rather than just keeping their fingers off the keyboard. I agree with blackbeard that the correct approach is to work from the noise source to the ears, rather than the other way. That is, reduction at source, then damping and absorption, then personal protection - that's the basic approach to all health and safety risk management. If you must use protection, then yes, as olewill says, such systems exist in aviation, but search on "aircraft cabin noise cancellation" to find relevant sites. Here's an example: http://www.avweb.com/avwebflash/news/Elliott_Rosen_SMS_active_noise_reduction_196945-1.html
 
William_H said:
I have seen a cabin noise cancelling system in a small business prop jet. Apparently very successful. Google for aircraft noise cancelling. I am sure they will sell you a system. Probably pricey though. I would think if you were seated in the centre of the weel house with speakers either side it could work well. Indeed if you got noise cancelling headphones and add 2 amplifiers in lieu of phone speakers then to 2 larger speakers it should work OK. Room for experiment.
However as said I have always thought there is no excuse for noisy engines in boats. Insulation and water cooled exhausts work well. I hear from home some boats incredibly loud exhaust while most are very quiet.(just like cars) do some people get high on exhaust noise? good luck olewill
Click to expand...

Now that sounds like a plan. I might try it out this winter. At the end of the day the only difficult bit is the actual algorithms. If the NC headphones have it embedded in their firmware then whoopee
 
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