Reviewed on: SoundStage! Solo, June 2021

I measured the EarFun Free 2 earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator with the RA0402 high-resolution ear simulator with KB5000/KB5001 simulated pinnae, and a Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. An Mpow BH259A Bluetooth transmitter was used to send signals from the Clio 12 QC to the earphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. Note that my usual impedance and sensitivity measurements are irrelevant for wireless headphones, and impossible to do without disassembling them, and are thus not included here. If you’d like to learn more about what our measurements mean, click here.

Frequency response

The above chart shows the Free 2s’ frequency response measured with the RA0402 ear simulator. I did these measurements after I submitted the review text, and was delighted to see that they exactly match my subjective impressions. That peak at 3kHz is pretty much “by the book,” but otherwise, this is a classic “smiley” response, with a big boost in the bass, balanced out with a broad peak between 7 and 11kHz.

Frequency response

This chart shows the Free 2s’ right-channel response compared with other true wireless earphones: the original Frees, the Grado GT220s, and the KEF Mu3s (which are the true wireless earphones I’ve found come closest to Harman curve). This chart makes it clear how boosted the Free 2 earphones are in the bass and the mid-treble.


The Free 2s’ spectral-decay (waterfall) response shows some hashy, super-high-Q resonances between about 7 and 11kHz, which corresponds with the big mid-treble peak in the frequency response. I’m not sure if this is an actual acoustical artifact or a Bluetooth-related artifact, but I see something similar around 2kHz when I measure spectral decay of planar-magnetic over-ear headphones. If it’s audible, my guess is that it creates a sense of “air” rather than the perception of a sonic coloration.


The Free 2s’ distortion is negligible even at the extremely loud level of 100dBA (measured with pink noise).


This chart shows the Free 2s’ isolation in its various modes compared with the original Frees, the Grado GT220s, and the Bose QC earbuds, which have active noise canceling. The Free 2s’ isolation is about in the same ballpark as similar designs.


Latency with the Free 2s connected to the Mpow BH259A Bluetooth transmitter is typically about 217ms. As the BH259A and the Free 2s both have aptX, I assume this is from an aptX connection, but the measurement with SBC should be similar. It’s enough latency to create mild lip-sync problems when watching YouTube videos or playing video games, but that will also depend on the latency of the display you’re using.

Bottom line: The EarFun Free 2 earphones definitely have a smiley response curve, but it’s well-balanced between the bass and treble, and the other measurements look fine.

. . . Brent Butterworth