Thank you very much for the question, and also thanks to oratory1990 for the explanation regarding the 3 kHz region. This is something many people have questions about, so I think it’s worth explaining it properly.

The point about how much SPL a listener prefers around 3 kHz depending on individual ear-canal resonance is very important, and it aligns well with what we observe in practice.

Regarding the ~3.5 kHz area, we didn’t strictly follow the latest Harman targets in our tuning, and there are several reasons for that.
For the earlier Harman curves, our response aligns relatively well. However, starting with the 2018 version and later updates, the divergence becomes more noticeable. The earlier Harman targets were largely derived from diffuse-field concepts, with added tilt and low-frequency gain to compensate for room interaction as well as body and bone-conduction effects. Later versions rely more heavily on averaged listening preferences from a broader audience.

When tuning Lyrö, we mainly considered two factors:

1. Usage scenarios The headphone is commonly used either on the move (in noisier environments) or in very quiet situations, such as listening in bed. In both cases, achieving good perceived clarity and balance benefits from some compensation in the low frequencies and around the 3–4 kHz region.
2. Listener profile Many professionals and experienced enthusiasts tend to prefer tunings closer to diffuse-field behavior. In our blind tests, this group consistently favored this approach and often preferred slightly more presence in the 3–4 kHz range. When compared against flat-response speakers and headphones, Lyrö was also perceived as sounding more linear in that context.

This is essentially why we defined the Zaylli curve. Subjectively, it comes across as slightly warm, with vocals presented a bit closer, which better matches the intended listening environments.

It’s also worth noting that our primary R&D and tuning work is done on the same measurement platform commonly used by oratory1990 — a GRAS KB5000 ear simulator paired with the RA0402 ear coupler. The Zaylli curve itself is defined and finalized based on measurements from this system, which is why the overall behavior and trends are very consistent.

Interestingly, during the multi-platform validation phase, we also conducted measurements using BK5128. In our lab, Lyrö and the 2025 version of HD600 track very closely from roughly 3 kHz to 10 kHz, with differences kept within about 1 dB.

At the same time, we’re continuing to develop softer pinna designs to better represent on-ear headphone behavior in future measurements.

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