Armour Home recently announced that it has been appointed worldwide distributor of Phitek System's BlackBox range of Active Noise Rejection (ANR) headphones and earphones. Phitek says that the level of ambient background noise can reach 60dB in a busy street, 80dB in the office and up to 94dB in the cabin of a passenger jet. The company claims that its technology is capable of reducing ambient noise levels by 90 percent or more, and I've been sent some C18 in-ear phones for review.

Active noise cancellation attempts to interfere with background noise signals by producing an anti-noise wave, 180 degrees out of phase with the measured disturbance. When the two sound waves collide, they cancel each other out. If not carefully designed, however, transducers used to measure the anti-noise response can add their own characteristics to the signal or worse, actually create bothersome noise.

Engaging such technology in headphones which totally enclose the ear (as opposed to supra-aural types) does increase the efficiency of the noise cancellation, but I must confess to having only ever been truly impressed by some rather expensive Denon cans, and that was more to do with the superb quality of the audio than the noise cancellation technology.

Phitek's Active Noise Rejection uses a proprietary feedback compensation network that's claimed to better regulate the noise level and enhance the dynamic characteristics of the speakers for improved handling of low and mid range noise levels. Control electronics included in the design are said to monitor performance in real time, so that the rejection of noise close to the ear is as high as possible.

Opening the BlackBox

The BlackBox range consists of two pairs of circum-aural headphones and three in-ear, bud-type phones – the latest addition being the i10 earphones, which have a 30-pin dock at the end of the audio cable for use with Apple devices. As I don't own an Apple device, Armour Home sent me the similar C18 earphones, which have a 3.5mm audio jack at the end of a 1.2-meter (3.93-ft) cable instead.

A 6.5mm jack adapter is also included in the box, and an airline-friendly, single-to-double 3.5mm adapter. There's also a carry pouch, AAA-sized battery for the in-line controller module, a lanyard and a user manual. The package comes with three sets of silicon ear buds of varying sizes.

As with other bud-type earphones, the C18s benefit from a certain amount of passive noise cancellation anyway, due to the buds creating a seal at the ear. The company claims that the ANR circuitry in the C18s offers active noise cancellation of up to 18dB under 1kHz, and passive noise isolation of up to 35dB from 1kHz. Each earphone contains a 9mm diameter, dome type, neodymium driver – the frequency response is 20Hz to 20kHz +/-3dB and the impedance is 50 Ohm.

The C18s come with a lanyard that secures to a clip on the cable of each ear piece. At 48 cm (18.89 inches) from the base of the earphone module, these cables converge to meet an in-line controller. The controller houses the ANR circuitry, is powered by a supplied AAA-type battery, and has a power on/battery status indicator to the top and a power on slider and a volume control to the right side (looking from the front). The battery is said to give about 50 hours of service before needing to be replaced.

Shutting out the world

Armour says that some users use the ANR circuit to just "shut out the world," so this was where I started. As the in-line controller module weighs about 32 g (1.12 ounces), most users will find it necessary to use the included lanyard to stop this weight from causing the buds to pull away from the ear.

As expected, plugging in the ear buds resulted in some screening out of the background disturbance, but after sliding on the power I noticed an immediate further reduction in low level background noise. I have to say, though, that the sound of our neighbor's dog greeting passers-by and the active chatter of the local bird population could still be detected.

I then turned on my media player to start my ten album Clutch marathon. Due to the in-ear design, I tend to keep my player's volume quite low, and the volume control on the in-line controller set to full gave a comparable output to my usual bud phones. It was a fairly windy day when I walked into town and I'm happy to say that the circuitry admirably took care of most of the annoying whooshing sound you usually get on such occasions.

I wanted to quickly compare the sound with and without the active circuitry engaged, but this wasn't possible as switching off the in-line controller's power turns off the source audio altogether rather than just bypassing the circuit. While disappointing for my testing, this is unlikely to cause users any problems.

I walked through a noisy outdoor market, then a busy supermarket and on towards a main road where redevelopment work was being undertaken. I went on to a park and walked down a number of busy roads. I've also been plugged in on a tram and a train but have not had the opportunity to try them out on an aircraft, where I can see them being of help drowning out irritating cabin noise.

At the end of the day ...

Overall, I found that the combined efforts of the passive and active noise cancellation technologies of the C18 did reduce much of the otherwise annoying background buzz of busy town life, the ANR circuitry seeming to work best when combined with music without appearing to add its own texturing. Due mainly to the weight of the ANR module, I would say that the test model is probably best suited to use in seated travel situations rather than jogging through the park.

I do have to award some points to my local collared doves, though, for managing to cut through the audio much of the time (if only they could coo in time with the rhythm).

Unlike the C18, the i10 earphones draw power from the connected device, making the in-line controller somewhat lighter, and have up to 22dB active noise cancellation under 1kHz. Both are priced at US$129.

Amour Home told us that it is "now the exclusive distributor for BlackBox in UK and everywhere except North America and Australia/New Zealand," where Phitek Systems continues to use established networks for distribution.

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