My friend and colleague Geoff Morrison is reviewing the new Bose QuietComfort 20 (QC-20) in-ear noise-cancelling headphones for Forbes and The Wirecutter, and he asked me to run some lab measurements on them and give them a listen.
On-the-go headphones like the QC-20 are more the kind of thing Jason Hidalgo reviews on the Portable Electronics page, but as of this posting no one at any other website seems to have measured them, so I thought I'd go ahead and post the measurements here. You can read Geoff's full Bose QC-20 review on Forbes.com.
Although I'm not doing a full review here, I will say that my impression of the QC-20 is about the same as my impression of Bose's QC-15 over-ear noise-cancelling headphone. The sound is better-than-average, the fit and comfort are the best in the business, and the noise cancelling function works so much better than any other manufacturer's that the QC-20 almost belongs in its own product class.
I measured the performance of the QC-20 using a G.R.A.S. 43AG ear/cheek simulator, a Clio FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-Can headphone amplifier. (I don't usually use the full ear/cheek simulator to measure in-ear headphones, but due to the unusual shape of the QC-20's silicon tips, it didn't fit well into the G.R.A.S. RA0045 coupler I normally use for measurements of in-ears.)
Measurements were calibrated for ear entrance point (EEP), roughly the point in space dead center at the opening of your ear canal. I used the clamp mechanism of the 43AG to assure a good seal of the headphone on the simulator, and a consistent result overall. Note that beyond the calibration to EEP, I do not apply a diffuse-field or other compensation curve. Recent research has questioned the validity of such compensation, and until the industry agrees on a good, research-supported standard, I prefer to show raw data.
Sensitivity of the QC-20, measured with a 1 mW signal at 32 ohms (my standard impedance calculation for internally amplified headphones like the QC-20) is 104.8 dB, high enough to get loud levels from probably any source device.