Reviewed on: SoundStage! Solo, March 2021

I measured the Sennheiser IE 300 earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 12 audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The earphones were amplified using a Musical Fidelity V-CAN. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

Frequency response

This chart shows the IE 300s’ frequency response. The bass looks pretty normal, and the response above about 5kHz looks pretty normal, but there’s something missing: a peak somewhere in the 2 to 4kHz range. The lack of this peak, and the rather prominent peak around 7.5kHz, are probably the reasons I sometimes found the upper harmonics of voices to be overemphasized.

Frequency response

This chart shows how the IE 300s’ tonal balance changes when they’re used with a high-impedance (75 ohms) source, such as a cheap laptop or some cheap professional headphone amps, or some exotic tube amps. There’s no significant difference.

Frequency response

This chart shows the IE 300s’ right-channel response compared with the JVC HW-FW01, Shure Aonic 5, and the AKG N5005 earphones, the latter being the earphones that come closest to the Harman curve target. You can see that all the other models have a prominent peak somewhere between 2 and 4kHz.


This is a very clean spectral-decay plot, with no hint of an audible resonance.


The IE 300s have a little bit of distortion, but even if you really cranked them, you probably wouldn’t hear it: it maxes out a little above 2% THD at around 1kHz, at the extremely high level of 100dBA, measured with pink noise.


In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. The isolation of the IE 300s is not as good as I’d expect, given their over-the-ear cable routing; I’d guess that their compact, lightweight design makes them less isolating than the Shure Aonic 5s (also shown).


The IE 300s’ impedance magnitude is amazingly flat for a dynamic driver, running 15 ohms at all frequencies, and there’s very little electrical phase shift.

Sensitivity of the IE 300s, measured between 300Hz and 3kHz, using a 1mW signal calculated for 16 ohms rated impedance, is 103.1dB. That’s about 3dB lower than what I extrapolated from Sennheiser’s 1V RMS rating, but it’s high enough that the IE 300s should play quite loud from practically any source.

Bottom line: The Sennheiser IE 300 earphones’ frequency response is pretty weird in its near-complete lack of an upper-midrange peak. I loved the sound, but I sure wish I had access to a listening panel to get some other opinions.

. . . Brent Butterworth