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Achieving Accurate Accelerated Audio Mixing With Genelec UNIO - Part 2

The origins of Genelec’s UNIO platform date back to the launch of our Smart Active Monitoring (SAM) family in 2006.

SAM technology automatically calibrates the loudspeaker setup to any given space, and since its introduction Genelec has been looking at how to create working environments which keep pace with the changing landscape of audio creation. Our goal has always been to provide engineers with an accurate mixing environment which can flex to different practical spaces, and enable them to continue working with confidence and precision.

This includes engineers who have no access to dedicated monitoring spaces at all, and the introduction of Genelec Aural ID technology was our first step to enable a headphone experience akin to listening on loudspeakers. The ability to transpose a calibrated immersive environment to a set of professional headphones means that the user can move seamlessly between in-room loudspeaker monitoring and headphones to create an uninterrupted, more efficient workflow.

Naturally, there are hurdles to overcome. The most prominent being that every individual has a unique way of hearing audio, which affects their headphone listening experience. This effect is known as the Head-Related Transfer Function (HRTF), and is created by the shape of a person’s head, ears, and upper body. This influences how the person interacts with and affects the sound reaching them, and everyone’s HRTF is unique. This is the reason why binauralized audio created using an average person’s head and ear shape – or even the HRTF of a mannequin head and torso simulator – may not be very successful in creating a reliable and accurate sense of direction and sound color, although it can create a sense of ‘externalization’, which is the feeling that the headphone audio is no longer located entirely ‘inside’ the listener’s head.

Accuracy In Binauralization

The first step to more accurate headphone monitoring is to provide professionals with their own personal HRTF, which is what Genelec’s Aural ID technology has been providing since 2019.

Aural ID creates and utilizes the user’s personal HRTF for headphone rendering, and it goes way beyond the capabilities of similar binauralization technology products. In terms of binaural audio generation, most services offer rendering of audio at ear height, while Aural ID covers the full 3D space around the listener, including levels below and above the user’s ears.

When users are monitoring immersive content using binaural rendering over headphones, it ensures that every loudspeaker in the monitoring playback system can be correctly represented in the binaural space – creating an accurate 3D soundstage and enabling reliable mixing. The soundstage experience and image presentation on headphones then closely resembles in-room loudspeaker monitoring.

Aural ID user interface.

Aural ID user interface.

This is a key component of the UNIO concept. UNIO enables headphone monitoring that is as reliable as listening on a set of monitoring loudspeakers. This capability is not limited to a certain format or monitoring channel set. It supports applications from standard stereo to a 9.1.6 configuration – with users able to access any loudspeaker or monitoring channel layout through headphones.

Personalization Is Key

Setup is straightforward. Using the free Aural ID Creator mobile app, a friend or colleague takes a 360 degree video of the user’s head following the detailed guidance provided in the app. This includes capturing details close to the ears, enabling Genelec to build a detailed 3D shape of the person’s ears, head and upper torso, and then uses acoustic modeling to calculate all the different directions of arrival for audio from more than 830 different locations. This data is then available in the Aural ID plug-in, and this enables precise rendering of audio in any direction. The plug-in installs in VST, AAX and AU formats into any DAW.

The Aural ID plug-in comes with head tracking support using standard computer webcams – as well as hardware trackers supporting the Open Sound Control (OSC) interface format – so that the binauralized monitoring loudspeaker set appears to remain stationary in space. These natural head movements strengthen the sense of externalization, and support an experience similar to listening to an actual set of monitoring loudspeakers. We deliver the personal Aural ID data to the user via their MyGenelec personal account, including the plug-in software install straight into their DAW. The HRTF binauralization options enable different styles of accessing the personal HRTF for both stereo and immersive monitoring, allowing access to either the complete raw HRTF or the directional (DTF) component only – as well as accurately maintaining the natural sound character of any professional headphones.

Mac users can also run the Aural ID 2.0 plug-in in a standalone ‘soundcard’ mode, to render any audio for headphones. This provides additional flexibility where a conventional plug-in inside the DAW can’t be used – such as processing audio directly from a stream or using Aural ID as a post-rendering engine when monitoring Dolby Atmos immersive content.

Personal Calibration

While Aural ID helps achieve accurate binaural presentation for an individual, there is a second hurdle to achieving maximally accurate binaural rendering, and in many ways, it is an extension of the first.

Just as everyone’s HRTF is different, so is every set of headphones, including how they interact with you as a listener. Every headphone design provides slightly different detailing of the frequency response, affecting spatial positioning and sound color, and this interacts with the listener’s personal physical features. This variation between headphones can be significant – and must be accounted for.

For this reason, Genelec’s Aural ID system gets even closer to mirroring the user’s in-room loudspeaker system by allowing manual adjustment of the azimuth, elevation, and level of each individual ‘virtual monitor’. Using the solo and mute controls on each virtual monitor, this enables personal calibration, and guarantees maximally accurate personal presentation of the soundscape for every individual. This headphone modelling of in-room monitoring is further enhanced by Aural ID 2.0’s advanced calibration controls, which subjectively adjust the overall tonal character of the virtual reproduction set.

Getting The Reference

So, we’ve looked at how the UNIO ecosystem combines Genelec Smart Active Monitoring with GLM calibration software and Aural ID binaural monitoring technology, to provide consistency between monitoring on in-room loudspeakers and headphones.

With the recent introduction of the 9320A Reference Controller, these elements are now tied together in a tactile and compact hardware format. As well as directly connecting to two SAM monitoring systems, it crucially also features a professional headphone amplifier with built-in calibration, to accurately adjust the presentation of the soundscape for headphones. These controls also integrate tightly with Aural ID to finesse the soundscape presentation with the user’s unique combination of HRTF and headphone choice. The combination of analog, AES/EBU and USB I/O connectivity means that the 9320A can enable monitoring directly on any system, including use as a high resolution output interface for stereo and binauralized audio from a computer.

Although the 9320A can support any active monitor loudspeaker system, it can also calibrate and manage an entire immersive network of Genelec SAM monitors via GLM 5 software. Integrating with a DAW or audio interface, the 9320A ensures compliance with EBU R128, ATSC A/85 and SMPTE RP200 standards, and doubles as a high-quality A-D and D-A converter, enabling connectivity to both monitor loudspeakers and headphones.

But more than that, it can also prolong hearing.

Noise Dose

Noise dose is all about measuring an individual’s exposure to sound and hasn't historically been something that the audio industry has consistently measured. But we really should, as it is vital in helping audio engineers ensure long-term aural health.

In heavy industry, the noise dose is frequently collected by placing a microphone on an employee’s shoulder over the course of a working day. The risk to hearing increases with exposure to high noise levels over extended periods of time, and the noise dose helps us understand the sound level required to ensure that a person can complete a full working day with no long-term hearing damage. 

9320A Reference Controller.

9320A Reference Controller.

When the daily dose is frequently exceeded, the risk to hearing loss increases. People in the audio industry tend to limit the dose by shortening the amount of time that they are exposed to these high sound levels. For instance, exposure to double the noise power (i.e. 3 dB higher) requires halving the exposure time in order to keep the dose the same.

UNIO’s measurement microphone provides sound level data as well as measurement of the incoming audio signal to the headphones, and this enables calculation of sound level at the listener’s ears – and therefore the noise dose. The 9320A Reference Controller does all this in the background, with no manual intervention, tracking the exposure to noise and calculating the dose accumulation during the working day. This information is immediately available to help the user plan their day for the best possible hearing safety.

Paradigm Shift

There has been a fundamental change in how content creators approach audio, with a clear shift from stereo to immersive. But the need for reliable monitoring has not changed.

Stereo environments are now looking to support immersive monitoring at an increasing rate. Immersive rigs are much more complex and more demanding, particularly regarding room space and acoustic quality. To present a reliable soundstage, they need more calibration than stereo systems and they may demand more rigorous acoustic treatment, particularly in difficult spaces.

At the core of Genelec's UNIO platform, the 9320A Reference Controller allows the user to instantly switch between accurate immersive loudspeaker monitoring and binauralized headphone monitoring with the same presentation. This level of monitoring reliability frees the engineer to work in any physical location, promoting greater mobility and the ability to confidently work in improvised environments. It ties Genelec’s entire UNIO ecosystem together.

We can’t wait to see where it goes next.