slow blog — Sony MDR–NC11A Earphones

Sony’s MDR–NC11A noise cancellation earphones work; they noticeably reduce outside noise. However, they are imperfect.

The earphones have a reasonable dynamic range (10—22,000Hz), a lot better than those supplied free with my iPod. They’re a lot more comfortable to wear. After a couple of hours wearing those free earphones, I felt I’d put sharp stones in my ear. I can wear these Sony earphones as long as I wish.

The earphones are inserted deeply into the ear. They are supplied with small, medium and large rubber fittings. You select whichever fitting is most comfortable for you. This close, deep fitting reduces external noise.

The device consists of a pair of earphones, a central control unit, and cabling. You wear the earphones with a cable running between them along the back of your neck. This cable can get caught in your collar. The left hand earphone has a second cable running to the control unit, which can be attached like a fat tie clip, or put in a pocket. Unfortunately these cables transmit rubbing on clothes as sound. Because the earphones are deep fitting, this sound is loud enough to interfere with the music, particularly when walking.

The triangular control unit requires an AAA battery, has a volume control, and an on/off switch. With that switch off, there is no noise cancellation; the device acts as an ordinary pair of earphones. When it is turned on, it both amplifies the music coming from the MP3 player, and cancels some external noise. Unfortunately, it adds a little background hiss. I soon got used to it, but others might find it irritating.

The volume control affects all output from the unit, so if you turn it down, both sound and cancellation is reduced. Thus using this wheel is useless for working out the effectiveness of the sound cancellation. I really haven’t understood the reason for it.

The sound cancellation reduces outside sound by about half. It doesn’t reduce sound for the entire dynamic range of the earphones (only 50—1,500Hz). It can’t handle white noise, nor wind noise, so they really stands out. However, it does suppress enough sound to be a noticeable improvement in most environments.

These earphones are early technology. They are imperfect, there are some obvious areas for improvement. Even so, they’re worth the extra cost over ordinary deep fitting headphones. I look forward to the technology improving: greater dynamic range of both cancellation and music, greater percentage of noise cancelled, and better cabling.

Type: dynamic, closed
Driver units: 9mm dia
Power handling capacity: 50mW
Impedance: 20ohms at 1kHz (power on), 8ohms at 1kHz (power off)
Sensitivity: 102dB/mW (power on), 98dB/mW (power off)
Frequency response: 10—22,000Hz
Frequency range of noise cancellation: 50—1,5000Hz more than 10dB at 300Hz
Power source: DC 1.5V, 1xRO3 (AAA) battery
Mass: Approx. 47g including battery box, cord and battery