Active Noise Control
#1
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Active Noise Control
The principle behind noise-cancelling headphones is as elegant as it is simple – sample the noise to be cancelled out and use small speakers to create an equal, but opposite, sound that effectively erases the problem.
Now, Toyota has taken that concept and applied it to one of its high-end hybrid cars to reduce interior noise for the comfort of passengers.
The company’s ‘Active Noise Control’ system appears in the new Toyota Crown Hybrid car and reduces the noise inside the vehicle by up to 8dB. It was implemented after the car’s engine was found to be noisier than expected as it rotates more slowly for better efficiency.
Toyota found that the low-frequency noises given off by the engine were more audible than in other cars with similar equipment under the bonnet and tackled it by first adding three interior microphones to listen in on cabin conditions.
Then, it installed three speakers – on the front doors and the rear shelf – to play back the cancelling signals. The car’s music system can still be used at the same time, of course.
Although describing the system like that is relatively simple, the acoustics inside a car made getting it right a challenge.
Unlike headphones, the in-car system has to deal with both direct noise and its echo when it bounces off interior walls. The result is a system that cancels out the engine sounds around head height – right where our ears are, in other words.
#2
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Honda has been doing this for years.
#3
I recall Lotus doing a lot of research in this area too. With the drive to reduce weight, everyone will want to reduce the insulation so this might be a good solution across the board.
#5
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Yeah the 2005 RL and 2005 Accord Hybrid were the first Hondas IIRC to do this.
The first car that could really be compared though is either the 2006 or 2007 TL added it whereas I know the 2004 and 2005 didn't have it... not sure on 2006. Anyhow... compare a 2004/5 TL to a 2007/8 TL to see how well the system works.
To me I think I can tell a difference but it's not significant and only really changes very low frequency noises. I heard it's supposed to also reduce exhaust boom, road noise, and potentially wind noise but those all sound pretty close to the same to me.
I read somewhere that the RL's designed was spared of about 50 pounds of added sound deadening material thanks to the system.
The first car that could really be compared though is either the 2006 or 2007 TL added it whereas I know the 2004 and 2005 didn't have it... not sure on 2006. Anyhow... compare a 2004/5 TL to a 2007/8 TL to see how well the system works.
To me I think I can tell a difference but it's not significant and only really changes very low frequency noises. I heard it's supposed to also reduce exhaust boom, road noise, and potentially wind noise but those all sound pretty close to the same to me.
I read somewhere that the RL's designed was spared of about 50 pounds of added sound deadening material thanks to the system.
#6
Lexus Champion
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You know I had a pair of Bose noise cancelling headphones, and my ears would hurt after using them for a few hours. I've had them for a few years, so I tought it was the nature of headphones, but they have worn out and I have switched to some $99 syberia headphones.... No more problems.
#7
We have an '05 RL with this feature, and it doesnt
do jack to the noise we get from the rutted concrete roads these ya-hoos build up here. Its so loud that you have to drive with your Bose 5.1 Surround Sound System cranked up so loud your ears are almost bleeding when you get to work...
I went to the IS350 recently in hopes of cutting this noise down some, and guess what - it didnt !!! Turn up the Mark Levinson 7.1 system honey, and text me, I cant hear a thing !!
DanF
I went to the IS350 recently in hopes of cutting this noise down some, and guess what - it didnt !!! Turn up the Mark Levinson 7.1 system honey, and text me, I cant hear a thing !!
DanF
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#9
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edit:
I found what I think you are referencing in this
http://corporate.honda.com/press/art...20010221001319
It's not active noise control. It's active driver control which only corrects for distortion in the speaker when playing music - it doesn't invert/cancel road noise. Very different.
Last edited by Threxx; 06-28-08 at 06:45 PM.
#10
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Well, I wouldn't say very different, but you're right. I remembered the active system (and even remember turning the stereo volume as high as it would go on my test drive and just spinning the volume **** with no effect, and the sound was perfect, no distortion), but not the details. Thanks for doing the research to clear that up!
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