In this article, Sam Hocking compares a selection of binaural plugins that share a common theme - they are multi-channel capable binauralisers similar to the more familiar Dolby Atmos binaural found in the Dolby Atmos Renderer. Included are details of the features and audio examples for each plugin.

More and more Dolby Atmos music is being experienced through Apple Music, Tidal, Amazon etc, when listening on headphones connected to Atmos enabled devices, but which tools are the best for producing a binaural render of a Dolby Atmos mix?

While the Dolby Atmos Renderer binauralises each object individually and offers each object and bed channel, as well as off, near, mid, or far within a binaural HRTF, when working in non-object or non-renderer channel-based formats there might also be situations where you wish to offer a binaural two-channel version perhaps for online use, streaming, podcasts, QC or are not needed to deliver a final Dolby Atmos ADM BWF object-based mix.

The plugins featured in this article are a selection of ones currently available that each offer something unique, many with surprisingly feature-rich controllability over the binaural processing compared to the Dolby Atmos Renderer.

The only criterion used for making the list was the plugin must be able to process a 7.1.4 multichannel input to binaural output. To help make comparisons, the plugins are demonstrated in a VST Host for easy solo switching. We also have versions available in the article so you can compare each plugin for yourself. The music used is commercially released and available on Apple Music & Tidal as Dolby Atmos.

An Overvew Of Terminology

For a very detailed overview of HRTF, terminology and binaural, I would highly recommend watching this video from Ben Supper titled ‘Spatial Audio: Showing You What You Already Know’, which also has a binaural plugin included in this comparision but to help you get started here is a summary of terminology is provided to jump into this review:

• Binaural: Stereo audio that is recorded through a dual microphone setup or emulated to create a 3D audio effect in headphones. We all listen binaurally with two ears.

• HRTF: Head Related Transfer Function. A pair of HRTFs are used to synthesize a binaural sound for a particular point in space. As we all have differently shaped bodies, heads, ears and pinna, different HRTFs can improve the binaural experience. They are typically measured in an anechoic chamber to minimize the influence of early reflections and reverberation on the measured response.

• Room Modelling: In the context of this review, this means adding some form of early reflection and reverberation to the HRTF binaural output. Some plugins have various room presets to choose from, and some have none to allow the engineer to add the room themselves.

• OSC Head tracking: Ability for the plugin to receive yaw, pitch and roll or quaternion instructions from an IMU (Inertial Measurement Unit / Headtracker) over OSC (Open Sound Control) via a matching IP Address and Port number.

• Non-HRTF: Simulating HRTF processing using algorithms and DSP processing rather than emulating with HRTF responses.

01 - Acustica - Sienna Sphere

Sienna Sphere is a relatively heavyweight plugin on CPU but packs a lot of features for finely adjusting the binaural image and some very useful monitoring capabilities unique to Acustica. Capable of binauralising up to 9.1.6, it is focused on replicating Dolby Surround & Atmos speaker formats. The standalone version also allows the processing of system-wide audio outside the DAW too.

Particularly useful features are the inclusion of Dolby’s Near, Mid & Far binaural render modes, Apple Logic (Apple Spatial) binaural and Steinberg Nuendo binaural. To have them all in one plugin is a unique selling point, as you can monitor all the binaural modes heard in Dolby Atmos / Apple Spatial used by the streaming services and in the Dolby Atmos Renderer. Unfortunately, such features make it a bit too heavy on the CPU to be used across many tracks in a session where you might want to mix near, mid and far modes (probably because this is all convolution-based emulation of those binaural flavours), but for Dolby Atmos & Apple Spatial QC work it gets you close enough to knowing how the mix or track will sound without needing to either load a DD+JOC mp4 to an Apple device, or track through the Dolby Atmos Renderer so has its uses, especially when working simply in multichannel modes before any Atmos mixing begins or with the need for a multichannel or binaural playback outside Dolby Atmos Renderer workflow.

Rather confusingly, there is room simulation as well as the room modelling happening in the binaural processing itself, which clearly isn’t how you would ever monitor Dolby Atmos as you’re either on headphones or on speakers, this is combining two worlds, and so I don’t use the room simulations and have an empty anechoic room. However, you can also dial in the ratio of the room/speaker to binaural anyway and so perhaps there is some creativity possible there?

Also included are over 300 headphone correction models to dial in frequency curves, which can help to improve the HRTF and accurately represent a room convolution in headphones The plugin offers very deep control of many parameters and is very much a comprehensive binaural tool and a monitoring solution and one I regularly use.

• Likes: Fine controls of all parameters & many binaural render modes and Dolby speaker formats to choose from.

• Dislikes: It will be a bit too CPU heavy for multiple instances within a session on anything but the faster computers. It would be nice if the inputs could be soloed and speaker positions are shown for the format selected. No head tracking or user rotation is possible.

02 - DearVR - Monitor

Its brother DearVR Pro is the more widely used plugin in the Dear Reality suite, but DearVR Monitor is intended to sit further along the workflow once you’ve mixed to a multichannel format you wish to binauralise and experience through a mix room on headphones. Deceptively simple, it offers a very clean and controllable binaural through its Ambience and Focus controls, although not to the level of detail possible in DearVR Pro, which is a shame. However, DearVR Pro isn’t capable of multichannel input. The binaural flavour in DearVR Monitor is Ambeo-only, whereas DearVR Pro only offers DearVR’s own binaural model.

Speaker input formats cover all the familiar Dolby Surround & Atmos formats up to 9.1.6 and are visually represented in the plugin, which helps with imaging and some visual feedback to what you’re hearing, which all helps add to the realism and even learning the different speaker setup configurations out there being used to check your mix with. It’s a shame the head rotation control is only a dial, and there aren’t any options to connect to your own head tracker, but it does at least allow some controller rotation to be heard/applied via automation.

The room modelling is very good, as you would expect from DearVR and allow presets from dry analytical, which is without any room modelling, through to more familiar spaces such as Mix Room A & B & Large and are comparable to Dolby Near, Mid & Far render modes in the Dolby Atmos Renderer.

• Likes: Simple layout, easy speaker visualisation and high quality of the binaural. Very similar to Dolby binaural and so could be trusted to QC with for some of the input formats.

• Dislikes: Lack of head tracking capability, no speaker/input channel isolation, no DearVR binaural mode to match DearVR Pro and no custom HRTF/SOFA capability.

03 - Fraunhofer - MPEG-H Authoring Plugin

While this plugin is part of the larger MPEG-H Authoring Suite and essentially the plugin version of the standalone MPEG-H Authoring Tool, it is available free on request from Fraunhofer for professional users.

It can be used to monitor any mix binaurally from mono through to 7.1.4. It’s particularly useful if you intend to publish to MPEG-H of course, but offers some unique features not really found elsewhere as it supports both object and channel-based MPEG-H Audio and so indirectly supports Dolby Atmos formats too.

Probably not the easiest to initially understand as this is more an MPEG-H rather than Dolby/Surround workflow, but all you need to do is connect up a multichannel input as a component, select e.g. a 7.1.4 speaker layout for it and binauralise it in the monitoring tab. The binaural HRTF is extremely good and as you would expect from Fraunhofer, although it does have a very wet room sound, which unfortunately cannot be controlled as it’s simply a final output binauralizer (unless working in the MPEG-H format and then channels/objects can be selected to be part of the binaural processing or not similar to Dolby Atmos). However, it is free and is essentially Fraunhofer’s equivalent of the Dolby Atmos Production Suite Panner & Renderer combined.

• Likes: A very high-quality free binaural plugin and also essential for any MPEG-H workflow you might like to look into. The interface is very logical, if not a bit technical when first trying to get sound through it. It includes loudness measurement, channel routing, downmixing and monitoring so useful if you intend to master binaural through this plugin for final delivery somewhere.

• Dislikes: Lack of head tracking and the binaural is a little too much room for some styles of music in my opinion.

04 - Ircam - HEar V3

HEar V3 is similar in concept to DearVR Monitor with minimal controls over the binaural other than speaker width and user angle (rotation) with some basic room presets included. Particularly welcome is the input routing matrix making custom channel routing and correction so much easier than some plugins allow.

The HRTF is based on the Kemar HRTF dummy model and so sounds familiar to many binaural listeners, but the Space presets offer various rooms and colourations, and Presets 1 to 3 are probably going to suit most situations, especially when wanting to emulate a Dolby Atmos near, mid far room feel.

OSC support is a welcome addition, but it’s unclear how or if this can be used with a head tracker, and OSC isn’t covered in the manual. I tried to connect a Supperware head tracker but without knowing what specific yaw, pitch and roll data it needs and in what format, I had to assume the OSC is for plugin controllers only.

Sound quality is excellent and very responsive, with options to report latency or not and use multithreaded processing when required.

• Likes: Routing matrix makes it easy to set up various channel configurations or customise new ones and the input metres visually give clues to the incoming audio too. The overall sound is well-balanced.

• Dislikes: No details about the OSC in the manual, no apparent head tracking possible, no custom SOFA, so it’s Kemar only.

05 - Kinicho - SMT

Still in Beta, this is a unique plugin and one you’ve possibly not heard of, but it has emerged as my favourite while beta-testing it over the last couple of months.

It’s not your traditional HRTF-based emulation, which immediately addresses high latency usually unavoidable in HRTF-based plugins. So this allows the head tracking and HRTF changes from it to be perceived with greater realism. When you consider the latency in Apple spatial head tracking is into 200ms  territory, this is well under 20ms and so feels very snappy with a good head tracker connected.

It’s described by Kincho as ‘an accurate physical simulation of perfectly positioned flat-response speakers in a virtual anechoic space for a fully volumetric spatial mix’ and the results are very impressive, although perhaps slightly underwhelming because the mix isn’t going to sound hugely roomy, but that is kind of the point of it. The mix should be artifact free from the non-HRTF approach and maintain the tonal and timbral integrity of the mix even once processed. That IMO is a priority, often not at the forefront of other plugins in this review.

As for features, the list proposed in this beta version are not fully implemented yet, but already every possible speaker configuration is possible up to 16 channels and the ability to create your own simply by entering the Azumth and Elevation of each speaker's position. This has the capability, therefore, to mimic your exact speaker positions in your studio or any studio if you have the measurements to hand. The addition of OSC head tracking for your favourite IMU is a welcome recent addition and works particularly well, especially with a low latency head tracker such as the Supperware Headtracker and will still maintain a total combined monitoring head tracked latency under 15ms.

Features proposed and still to be added during this beta phase are Volumetric Room Effects and Speaker Response Modelling. The current speaker simulation assumes a completely anechoic room and so this feature will also include volumetric reflections and reverb similar to other plugins. The speaker modelling is said will allow the matching of real-world response curves of specific monitors. This is essentially addressing the plugin currently only having a perfectly flat frequency response when in reality, most studio monitors and rooms are not perfectly flat and so this will also be simulated in due course.

Overall, this is a very interesting plugin, although too early to make too many conclusions. At the time of writing, access to the beta program is still possible, and I believe is open to anyone, but do check first.

• Likes: Complete freedom to position speakers and full OSC Head Tracking support, and very welcomed transparent sound.

• Dislikes: A little too early to judge when in the early beta stage, but the interface feels like it will need some work. Saving presets is possible but not editable, and the standalone version is macOS only.

06 - Noisemakers - Binauralizer Studio

Based on a Neumann KU 100 HRTF, this is a solid and very clear-sounding binauraliser, with its main feature being the ability to import your own custom HRTF SOFA for better binaural results from resources like the SOFA Conventions database or even your own personal SOFA if you have one.

Similar to DearVR Monitor, input speakers are viewed from the listener's perspective and can be soloed. This is a very welcome feature often overlooked by plugin manufacturers. Besides a gain fader and an LFE lowpass switch, there are no controllable parameters or room modelling. I feel it’s missing at least rotation support, but for mix room monitoring, its a very good and CPU-friendly minimal multichannel binauraliser.

• Likes: Custom HRTF & simple interface with speaker isolation

• Dislikes: No head tracking or rotation possible

07 - NovoNotes - 3DX

08 - Sound Particles - Space Controller

A relatively new arrival, this plugin combines input panning and/or bus output binauralisation into a single plugin with a unique feature for panning sounds using your mobile phone. You can view it a little like DearVR Pro+Monitor combined. Although it typically isn’t seen as an option to buy just to binauralise your audio, it does it and does it very nicely with several unique features and so is included in this review.

I don’t personally use the mobile phone remote control option or the panner, but can see it being useful for live use or to quickly get some panning ideas flowing into a mix before committing it to automation. It also offers the ability to import back through the Dolby atmos panner in the DAW for full Dolby Atmos automation and metadata control.

Similar to Kinicho SMT & SPARTA Binauralizer, speakers can be positioned using either cartesian or polar coordinates depending on your preference in the 3D viewer set as a cube or sphere. Clear input metering shows the multichannel audio entering the plugin and binaural output, although speakers cannot be soloed anywhere unless you turn all speakers down individually, which isn’t practical.

There are no binaural or room controls, it is simply the standard anechoic generic Kemar/Neumann head style HRTF of the anechoic style, it seems, so any room modelling would need to be added manually with multichannel reverb and delays etc.

Again, this plugin has no OSC head tracking support, even though there is a scene rotation capability, and the Android/Apple control app supports OSC. Overall the binaural is good and comparable to other binauralisers, but this plugin is really more about the panning, so it’s not immediately obvious to use it.

• Likes: Cartesian or Polar user interface and easy-to-understand speaker positioning with coordinates or using a mouse.

• Dislikes: No Head Tracking despite rotation feature, no room modelling and no soloing of input channels possible.

09 - SPARTA - Binauraliser

This is undoubtedly the most advanced and well-thought-out binauraliser in this review. It ticks all the boxes with custom speaker formats, custom HRTF, OSC Headtracking and up to 64 speaker support.

It would be nice to have some control over adding/editing room reflections and feel, but this is easily added with multichannel reverbs and often the preferable workflow for many spatial audio professionals anyway. This NF version adds a Near Field proximity filtering function, which reproduces the binaural effects of nearby sound sources discussed in this ScienceDirect paper Distance rendering and perception of nearby virtual sound sources with a near-field filter model.

Likes: Everything in one screen, fully customisable in both channel input and binaural output

Dislikes: No room reflections, so additional plugins are required if a room sound is required over the HRTF.

10 - Supperware Binaural

You’re only likely to discover this plugin once you have purchased one of Ben Supper’s head trackers. It is a very well-thought-out and featured binaural plugin freely available to download. Designed to use with the Supperware head tracker, it will work perfectly fine without it.

Similar to Kinicho SMT, I believe it isn’t HRTF-based, unlike the majority in this list, and so allows for extremely low latency. With Supperware’s head tracker being class-leading in its price point for low latency, too, the combination offers head-tracked binaural supporting latency low enough to be imperceptible, making it capable of achieving results really only seen in academia and research until now.

For comparison, an Apple AirPod with Head Tracking enabled will have over 200ms of latency added to the processing of your head moving and hearing that change in the binaural HRTF, here we are seeing <20ms and even lower if your system can run reliably at very small buffer sizes.

The speaker formats included cover everything you are likely to require, and Supperware is open to adding more formats and kindly included SPS/Mach1 for me recently. Ben is extremely knowledgeable on the subject of binaural and head tracking, and this plugin is regularly used for both multichannel, stereo and simply playing back music online.

The interface is self-explanatory, with the familiar 3-room model roughly representing near, mid and far approach. Speaker isolation is simply a matter of clicking a speaker, although custom speaker positions would need to be requested from Supperware. A feature not seen in any other plugin is the option to choose a near-field or full-range speaker setup. New updates are regularly added, and Supperware is very open to discussing your requirements. Supperware is also the official head tracker for L-ISA Studio.

The binaural is extremely good with clearly defined sound placement, and the adjustable reverb ratio is very useful, especially when mixing multiple inputs.

• Likes: Automatic integration with the Supperware Headtracker, Clean Binaural with room control and very low latency.

• Dislikes: Would be nice to be able add/edit speaker positions. No AAX option.

Audio Examples

A Dolby Atmos Binaural render of the ADM for this track is also kindly provided by Artist/Engineer McKay Garner so that you can have context for what each plugin is or isn’t adding compared to the Dolby Atmos Renderer binaural or your headphone playback mobile device from Tidal or Apple Music. The 7.1.4 playbacks are a channel-based re-render from the ADM file and so essentially represent what would be the 7.1.4 speaker output in a studio. The Dolby Atmos Binaural playback also referenced is the Dolby Atmos Binaural Render, also as heard in the studio if listening on headphones with binaural enabled.

You can find McKay Garner’s track ‘Envelopes’ on Apple Music or TIDAL.

All the audio examples have been time aligned and normalised to -18LUFS. We start with the DAPS Binaural version as a reference point.

Sam Hocking has an extensive collection of videos on his youtube channel. Use the button below to find out more.