We are all for transparency in our reviews. Measurements can be an important visual aid to support the sound description. Here we will share raw and uncompensated measurements. We perform the frequency response curves on a 60318-4 make in-ear coupler, which is the follow-up to the infamous IEC 711.
As opposed to loudspeakers, for IEM we do not want a flat curve.
Notes
- As opposed to loudspeakers, for IEM we do not want a flat curve. Due to evolution, our ears are designed to enhance certain frequency ranges. Depending on the research, you will find that our ear shape boosts the 3 kHz area up to 15 dB. On average, this value is a bit lower but at least 10 dB. It also might shift a bit lower to 2.75 kHz or slightly above 3 kHz depending on your individual shape. We have subtly added a reference in the graphs for orientation. This frequency deformation helps us to communicate as it increases speech intelligibility and clarity. However, it also helps to alert us and pick up less enjoyable sounds. This is why in most curves you will see that this range is not following the recommended target, although for a neutral reproduction they should.
- We mark a resonance peak in every measurement. Just like the real ear canal, the coupler creates a closed cylinder with inserted IEM. This results in standing waves with nodes at the harmonic waves. Thus you will find that a high-frequency range might be unnaturally boosted. In fact, this resonance is also apparent in your ear canal, but due to different material to an arguably lower extent. This peak is highly dependent on IEM design and fit and it may also overlay with an actual peak. Correlating with insertion depth, the resonance peak can be shifted higher or lower. It is important that whoever performs the measurement also listens carefully to the product and matches his hearing to the actual measurement. Only that person can tell you exactly which peak is the resonance. Very important to keep in mind: your experience might be different due to an individual ear shape, use of different ear tips or simply different anatomy.
- We did not define a target for the bass response. Basically, it could be linear flat and follow the 90 dB SPL line. Though based on preference, most people enjoy a low-end boost to compensate for the lack of physicality from earphones. An enhanced low-end can also compensate for lower listening volumes. Depending on how low the distortion is, a 6 dB increase at 60 Hz can still be within the neutral/natural realm.
- We perform the measurements from an ultra-low impedance source. This is at least an RME ADI-2 DAC or a Chord Hugo 2. IEM can be very sensitive to the output performance of the source (or cable), which is why other sources might show different curves or your listening experience might not match the measurement.
- The frequency response is subjectively the most important factor for sound quality. However, it is not the whole truth. Distortion, phase and transient response are just a few more important qualities that help to define sound quality. You will find that IEM that measure similarly might still perform very differently.
- Product variance is a thing. We have often encountered that an IEM might sound slightly different with every unit. This is less likely at higher prices and stricter quality controls, yet still nothing unusual. Add to that, that measurements also have room for error. Take everything with a grain of salt and trust your ears first!
Very important to keep in mind: your experience might be different due to an individual ear shape, use of different ear tips or simply different anatomy.
Database
Table loaded from Google Sheets: direct link.
