True-Fi technology

Sonarworks technology delivers studio sound experience on consumer headphones. Find out how it works!

Frequency response and its translation to the
consumer experience

Any audio playback device has many parameters that contribute to the final sound they produce. For headphones, the most noticeable characteristics from the user’s perspective are the type of headphone design (over-ear, one-ear, earbud, IEM or in-ear-monitor) employed, and the level and type of environmental noise isolation implemented. However in terms of sound reproduction performance, there is no aspect more important than frequency response.

The human auditory system is capable of interpreting frequencies in the range of 20Hz to 20kHz - this is the reason any musical digital audio signal is tailored to hold audio information within said frequency range. The frequency response between different headphone models differs drastically, as it is affected by their physical characteristics.

Frequency response graphs of popular studio headphones.

In essence, the frequency response curve of a transducer conveys which set of frequencies are attenuated or boosted by the playback device, making different headphones sound harsher, brighter or boomier than others even though the original input audio signal remains the same. When listening back to the same track through different headphones, the consumer gets differing sound quality and experience due to the audio dynamics being affected by the frequency response of the headphone model. This results in a distinct, audible artifact, as the link between the conscious decisions in frequency balancing and dynamics made by the producer in the studio, and what consumer hears in the end, can be lost.

Our goal is to ensure that the exact content the producer generated in the studio is not only digitally, but also physically delivered to the end consumer’s eardrum by ‘fixing’ any unwanted signal processing and nonlinearities imposed upon the audio signal by the chosen playback device, allowing full ‘translation’ of an audio signal between all headphones.

How we do it

The core of sonarworks is convolution-based equalizer with an equalization curve unique to each headphone type and model. The purpose of equalizing the input audio signal is to compensate for deficiencies introduced by the playback medium, allowing the end consumer to hear the sound exactly as the sound creator intended without any added coloration.

With True-Fi, the final output frequency response of the transducer can be made flat, meaning that the frequency content exiting the headphone driver is neither boosted or attenuated - all frequency bands remain in the same relative ratio as they were when the final mix was rendered in the production studio. In other words - calibrated headphones are tonally indistinguishable from calibrated studio speakers.

Different headphone frequency response after calibration

Headphone measurement is done with measurement tools developed in-house, which make sure the measured data conform with what's actually heard. For measurement reliability, multiple units of the same headphone model are tested and frequency responses captured, generating the true average response of the particular headphone model. As a final step, the full-frequency-range calibration curve is proofed to the in-house headphone reference target by a team of in-house engineers before deployment to the market.

Sometimes preference trumps reference sound

A flat sound target, originally meant for studios, so far has been widely appreciated by listeners. However there can be exceptions, as it's hard to argue about individual hearing specifics or preferences. An important aspect of sound personalisation is hearing loss compensation. With age, many people start losing high frequency hearing, meaning that it needs to be compensated with higher levels. True-Fi offers research backed hearing loss compensation that's adjusted both for age and gender. Another aspect, True-Fi allows for bass adjustment to retain a boosted low end while correcting the rest of the spectrum.

A set of headphones calibrated to produce a flat frequency response curve can have another frequency target curve layered to reproduce the characteristics of virtually any sound balance preference. With True-Fi, the calibrated frequency response can be tailored to adjust any preferred targets by artists, music engineers or end consumers - the switch from neutral balance to a more specific target is just a click away. The target curves that can be layered on top of a flat calibration are limitless.

Furthermore, not only can a large number of headphone models be replicated, but an arbitrary frequency curve target can be applied to the calibrated headphone set. This opens up a whole new world of possibilities in audio source creator-to-consumer transmission. Band members can now layer a frequency curve target that depicts how they individually envisioned the sound of a track. This target curve can then be digitally delivered with the track, and can be dynamically turned on and off by the end consumer. Sonarworks provides a medium to objectively share the same audio experience amongst listeners using different headphone models, adds another layer of experience and interaction between the artist and the end audio consumer, and allows each user to explore their sound tastes in an intuitive and automated way.

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