The Nokia Bh-905i that i have been playing with for a while, has a very interesting feature, which is the USP of this device imho.Its called Active Noise cancellation (shortened as ANC).I am going to discuss this feature in detail after the break.
Now what is active noise cancellation ? Simply put, it cancels the surrounding noise that affects you, in realtime. Note that it doesn’t actually cancel ANY noise, but only ambient noise that is persistent around you, but in a wide range of frequencies.
so,how do you activate it ?
The Active noise cancellation switch is present near the charging port of the BH-905i. So just push the slide switch to activate the ANC(the LED near the switch turns green),and when you do that , multi array mics present in the BH-905i get activated. Note that it will take a few seconds to start the process, you may find out why soon, below.
Now,lets see what Nokia has to say, about this technology :
Wolfson AudioPlus[TM] Ambient Noise Cancellation technology uses
patented signal processing technology and advanced acoustic design
expertise to deliver class-leading active noise cancellation for stereo
headsets and headphones.
This novel feed-forward technology cancels more decibels of noise
across a wider frequency range than traditional feedback technologies,
providing a peaceful and tranquil environment for users wherever they
happen to be. As Wolfson’s advanced technology does not process the
playback audio stream, your music comes through in untouched hi-fi
So according to Nokia, it is also called Ambient noise cancellation, which sounds more truthful to its doings.And it does not process your playback audio, it comes untouched. Intriguing to know how, right ?
From the above quote you can notice that it uses Feed forward technology to cancel the ambient noise. So, what is feed forward technology which plays a key role in this whole ANC thing ? i asked my friend Wikipedia and the good ol’ myself in college(being an engineer) for help and this is what i inferred :
First, let’s see what feedback is.In Control systems, for example, lets take a user interactive system, a process(the input) goes through some operations to give the output, the sample of the output is taken back to the input for reference and thus feedback is implemented. So, the difference between the input and the output is taken as feedback . Now, the exact opposite of this is feed forward. What happens is,the processing is done before the input and thus you get pre-defined set of operations which doesn’t act according to the output. This is what exactly happens in the Noise cancellation of BH-905i, the operation of eliminating the noise happens pre-defined, and so it does not touch the audio that plays through your headset.According to nokia, this setup is far better than older feedback based noise cancellation techniques, and i can see why.And since it pre-processes the noise cancellation, it takes 2-3 seconds for activation in realtime, now you get it, right ?
Now that we know what active noise cancellation is, let’s see some practical usage scenarios.
If you happen to travel a lot, using public transport , the ANC may prove very useful. For example, while traveling in my city transport bus, i preferred to use the BH-905 i, just pushed the ANC switch and bang! immediate silence.And while riding as a pillion on a bike, the ANC caused a lot of noise, quite the irony,eh ? while trying hard to cancel the noise, it lets in some whisshing sound of air , surely ambient noise is canceled but sadly, the effect is spoilt while riding in an open vehicle.
One more intriguing use of the ANC is its offline capabilities, i mean without being connected to the phone, you can use the ANC, just like that. Well,if you are in a noisy surrounding, and not in the mood for a song, just push the ANC switch and have a drink, in peace.
So, thats it from my side, about the Bh-905i’s USP ,the active noise cancellation. I have told you what i know. Now i need feedback from you.
Like the article ? What more features of BH-905i should i cover in the full review?
Comments section is open for discussions 🙂