Sony aren’t the first company to promise believable surround sound on headphones. But are they the first to deliver it?

Very occasionally, a new product creates a real buzz within the industry. Word spreads in trade‑show corridors and dealer showrooms, and suddenly everyone is clamouring to hear this new phenomenon. Sometimes it turns out to be a damp squib. Sometimes, as in the case of Celemony’s Melodyne all those years ago, it’s the start of something very special. It’s been a while since anything else had that sort of impact, but the jungle telegraph has definitely been sounding about Sony’s 360 Virtual Monitoring Environment.

On the face of it, that might seem odd. After all, isn’t Sony 360 Reality the ‘other’ immersive format in a market dominated by Dolby Atmos? And aren’t there plenty of other products on the market already that promise to deliver immersive virtual control room environments on headphones? Well, yes, and yes — but also no.

First of all, 360VME is entirely agnostic about, and independent of, mix and delivery formats. It can be used to mix material in Sony 360 Reality, but it’s equally capable of supporting Dolby Atmos, 5.1 and indeed stereo. And second, whilst there are other products that virtualise control‑room monitoring, 360VME has a unique selling point. To explain the significance of this, it’s worth a quick delve into how these products work.

360VME is entirely agnostic about, and independent of, mix and delivery formats. It can be used to mix material in Sony 360 Reality, but it’s equally capable of supporting Dolby Atmos, 5.1 and indeed stereo.

Acting On Impulse

No matter how many speakers there are in an immersive setup, a human listener has only two ears. These can be considered single‑point receivers, like microphones. Thus, in principle, it should be possible for an impulse response to perfectly describe how the sound from any given speaker is reflected, refracted, absorbed and otherwise coloured on its way to each ear. And if we can generate a set of impulse responses mapping each speaker onto each ear, we can recreate the sense of listening in a 3D space on headphones.

In practice, there’s a problem that limits how faithfully this can be done. The most important source of coloration in this context is the physical geometry of our own head, torso and outer ear. Our perception of direction is derived from the filtering effects introduced by these structures, so in order to ‘binauralise’ headphone sound, the filters we apply need to perfectly describe the effects of the listener’s head geometry. Considered independently of the room and speakers, these are known as the head‑related transfer function or HRTF.

The limiting factor is that no two people have the same head, ear or torso shape. So in order to create a viable commercial product, manufacturers need to either work out a practical way of measuring the HRTF of the person who’s going to use it, or choose a generic HRTF and hope that it will be close enough. In the past, the latter option was the only feasible one, but in recent years, we’ve seen several attempts to derive personalised HRTFs from visual sources. Genelec’s AuralID, for example, can do so by analysing a video of your head, whilst Embody’s Immerse Virtual Studio uses just a photo of the ear.

Once the HRTF has been calculated, it can be superimposed on the characteristics of a control room to create a virtualised listening experience. In some cases, such as AuralID and APL Virtuoso, these characteristics are derived from first principles, to create an ‘ideal’ control room. In others, including Immerse Virtual Studio, they are measured in real‑world control rooms. Either way, there is no such thing as a completely neutral set of headphones, so it’s often desirable to add further equalisation to compensate for the headphone frequency response.

Profile Pictures

What’s different about 360VME is that it it uses a single set of measurements to capture the characteristics of all three elements: the room and speakers, the headphones, and the geometry of the ears and head. It’s not just creating a personalised HRTF and applying that to a generic room simulation, or an impulse response recorded separately. It’s measuring the entire system, with the listener in place.

In order to use 360VME, you will need a file that Sony call a Profile. This is based on measurements taken in the space you wish to replicate, and needs to be done by an authorised representative of Sony. Because your ears and the room are…