Sound in the round: the arrival of 3D audio

Source: Dolby

Dolby’s Atmos demo room in London was the UK's first 3D audio cinema

The latest developments in audio technology could bring the 3D cinema experience to your ears as well as your eyes.

A helicopter roars overhead as the sound of sirens appears in the distance, the cars drawing gradually closer before circling the building. You start to hear rain hitting the roof above you and trickling slowly to the ground. Then an almighty explosion engulfs the theatre, passing from front to back as bullets fly past your seat. Luckily, none of this is real. These are the sounds of the next generation in immersive entertainment to hit cinemas: 3D audio.

We’ve already become used to watching images pop out of the screen or disappear into the distance when we’re enjoying the latest blockbuster movie with 3D visuals. But most people have yet to experience 3D sound, even though it was invented decades ago ­– a fact that could be about to change. In some forms, it’s an evolution of the surround sound we’re used to encountering in cinemas or home entertainment systems. However, the concept of 3D audio isn’t necessarily about placing more speakers around an audience; it’s about recreating sounds in a way that tricks listeners’ brains into thinking they are hearing them live rather than as a recording.

Inside a small, specially designed room in London’s Soho is one of just two examples in the UK of perhaps the most advanced commercial cinema sound system in the world: Dolby Atmos. Actually, it’s a room within a room, created to insulate screenings from the vibrations of the nearby Tottenham Court Road station (currently being rebuilt to accommodate Crossrail). Rows of speakers not only adorn the walls and hide behind the screen but also hang from the ceiling, ready to envelop the audience in sound from (almost) all directions.

The clever part of the technology, however, is invisible. As well as traditional dialogue, music and background sounds sent to different speakers, films mixed for Dolby Atmos include a number of individual sound effects known as “objects” designed to move between speakers as smoothly as if you were hearing them move in real life.

Typically, sound files such as movie soundtracks are mixed to a specific number of tracks or channels, each feeding a different signal to a separate speaker or array of speakers in a different part of the room. This number has grown over the years from mono (1), to stereo (2), to the now commonly used 5.1 (which includes an additional bass signal to a subwoofer), and on through a number of formats up to 22.2.

Rather than adding to this number again just to accommodate more speaker signals, Dolby Atmos uses the first 10 channels for the traditional soundtrack and a further 118 for the moveable objects. Each object signal includes extra information known as metadata that tells the speakers’ control system the three-dimensional coordinates of where in the room that sound should play from at any one time. As the coordinates change, the system uses different speakers to recreate the sounds in the right location, producing the illusion of a moving audio source.

‘For the first time now we’re opening up the possibility of having very precise sound coming from around the room, and those sat in the front will get a different experience from those sat in the back because as the sound pans around it will get remarkably quieter [as it gets further away],’ said Julian Pinn, director of cinema marketing at Dolby Europe, speaking at a recent demonstration of Dolby Atmos for the Audio Engineering Society.

“True 3D sound systems can aid the sense of reality and opens up many new creative possibilities

Dave Hunt, Immersive Audio

This precise level of control is what really differentiates 3D audio from conventional surround sound. And the technological breakthroughs that are enabling it, including Dolby Atmos, are creating real excitement among sound engineers who are ready to move their craft to a new level. ‘True 3D sound systems allow much better reproduction of spatial direction of sounds, moving sources and an acoustic environment which contains them,’ said Dave Hunt, a sound engineer from the recently founded firm Immersive Audio, set up to provide 3D sound installations to performance venues and live events. ‘It can aid the sense of reality (or artfully constructed hyper-reality), and opens up many new creative possibilities.’

Source: Warner Bros Pictures

The Hobbit is one of the first films with an audio track mixed in Dolby Atmos

So far, several films including Disney Pixar’s Brave and more recently Warner Bros’ The Hobbit have been released with an Atmos-mixed soundtrack to a handful of test cinemas, in advance of the system’s commercial launch in April this year. Because the object information is contained in the metadata not the main sound signal, Dolby doesn’t need to produce two versions of the soundtrack. Plus, the system doesn’t require a special cinema design: each object signal is encoded with spatial coordinates rather than sent to a specific speaker channel, so the Atmos software will render it to the best location regardless of the overall speaker setup.

‘With that in mind it gives us the ability to tailor the number of speakers that a given space will have depending on the size and shape of that auditorium,’ explained Pinn. In Dolby’s Soho screening room there are 26 speakers; in the Leicester Square Empire – the UK’s other Atmos-equipped cinema – there are around 40. The Dolby Theatre (formerly the Kodak Theatre) in Hollywood, meanwhile, essentially uses a hybrid of two and a half Atmos systems to cope with the auditorium’s balcony.

Although Dolby has so far only focused on the cinema market, this adaptability of object-based 3D audio systems means they could transition to domestic use relatively easily. In fact, there are a variety of techniques for producing 3D sound that could offer similar flexibility that could find their way not only into home entertainment systems but also the growing number of computers, tablets and mobile phones used to watch TV.

With this in mind, the BBC has set up an Audio Research Partnership with the universities of Surrey, Salford, Southampton, York and Queen Mary, University of London, in order to explore the possibilities for bringing 3D or spatial audio to television programme making, broadcasting and watching. ‘The most important thing for the BBC is to deliver very high quality to the audience and always look for new experiences,’ said BBC head of audio research Frank Melchior. ‘If we go back in history and look at what are the developments in audio formats, there hasn’t been much in the last decade. We would like to deliver a new experience to the audience, but this time it has to be flexible enough to deal with the habits of the audiences and multiple devices.’

As with Dolby Atmos, the key to this flexibility is the ability to take the different tracks of a sound file and use software to render and optimise them for the specific speaker set-up or device the viewer is using – the opposite of current 5.1 broadcasts that are optimised for speakers in set positions. ‘You can also imagine if you have these separate elements in your scene not mixed together then you can have also room for changing and adapting them, for example bringing in personal preferences or just changing the language of a movie,’ said Melchior. ‘So they open up a whole new dimension of new experiences, not only 3D where it’s really helpful but also there is a lot of new potential within these new representations of audio.’

3D audio theories

Three-dimensional audio goes back almost to the start of recorded sound and a variety of approaches have been developed to produce it. One method the BBC and its partners have been examining is binaural sound, a very old technique where two microphones are used to capture the same sound signals a person hears through their left and right ears, and the subsequent recording is played back through headphones. The signals are often recorded using microphones placed inside the head of a mannequin to get as close as possible to those picked up by human ears.

Another spatial audio approach known as wave field synthesis (WFS) dates back to the late 1980s. It uses loudspeaker arrays to synthesise wave fronts in such a way that you can control where the sound appears to be coming from. The advantage of this method is that – unlike other 3D sound techniques including ambisonics – it doesn’t create a sweet spot, outside of which the spatial audio effects break down. WFS systems have been installed in a small number of cinemas worldwide in the last few years, including in the famous Chinese Theatre on Hollywood Boulevard, although the large number of speakers need to make it work may have limited its spread.

One of the techniques the BBC is experimenting with to produce 3D audio is known as ambisonics, which attempts to go further than just controlling the signals received by the listener’s ears and instead create or recreate an entire sound field within a space. Invented by British academic Michael Gerzon in the 1970s, ambisonics involves combining a number of sound signals recorded or synthesised from different directions, based on a mathematical theory called spherical harmonics. Recording basic ambisonic sound requires three mics in the X, Y and Z directions and a fourth omnidirectional device; higher order recordings use additional microphone signals, processed to give even more sophisticated directional information. Specialist software can then combine the signals and use them with an array of loudspeakers to produce a sound field very similar to the one where they were originally captured.

The BBC has recorded the Last Night of the Proms using ambisonic sound

‘You can see ambisonics as something in between the channel- and object-based approaches,’ said Melchior. ‘You come up with a kind of scalable representation of the spatial audio scene and adapt that to a different speaker layout by decoding it, knowing the speaker positions and trying to adapt the representation to that layout, but you no longer have access to single elements in the scene. It’s not like the object-based approach where you can just take out the dialogue, for example. But you can make sure that if the centre speaker in the setup is not in the right position you can adapt the whole scene to that case and get the correct spatial reproduction.’

“We would like to deliver a new experience to the audience, but this time it has to be flexible enough to deal with the habits of the audiences and multiple devices

Frank Melchior, BBC R&D

One of the obvious uses for replicating an entire sound field is in live music recordings, especially of large bands or orchestras performing in unique venues. Sound engineers have long tried to reproduce on record the atmosphere of a concert, complete with echo, reverberation and background noise. Ambisonics adds to this a precise sense of exactly where all the musicians are playing in the room, allowing a listener at home to close their eyes and imagine they are at the concert. The BBC has already experimented with ambisonic recordings made at the Last Night of the Proms at the Royal Albert Hall and at a performance by award-winning band Elbow in Manchester Cathedral.

However, ambisonics is just one approach to creating this kind of spatial audio. Part of the challenge for the BBC Audio Research Partnership is to experiment with capturing and mixing 3D audio signals in a variety of different recording locations, whether that’s a controlled radio studio, a more unpredictable outdoor film set or an entirely synthesised environment. These signals will then need to be transmitted to and reproduced through relatively affordable and practical equipment in the home.

Members of the Partnership at Southampton’s Institute of Sound and Vibration Research are working on an alternative method for generating spatial audio based on mathematical techniques derived from a theory known as inverse problems. Developed in collaboration with the Korean Electronics and Telecommunications Research Institute (ETRI), this involves recording and examining a sound field and then effectively attempting to reverse-engineer it using active sound control, where the signals from different speakers interfere to create a specific pattern of sound. The researchers say that compared to other techniques, their approach is more adaptable to almost any speaker configuration.

To test their signal processing algorithms, the Southampton team, led by Prof Philip Nelson and Dr Filippo Fazi, has built a huge spherical array of 40 loudspeakers that each send out a different component signal. Inside is a microphone array that measures the resulting sound field, analysing phase and amplitude for all the different frequencies, to determine if it has been reproduced accurately. The sphere also provides a great platform for the researchers to hear what the result sounds like, which feeds into another element of their work known as psychoacoustics.

Source: University of Southampton

Fazi and team setting up the spherical array

‘The physical reality of the sound field is described by a very large number of physical observables that have a very high degree of complexity,’ said Fazi. ‘We can simplify this process but obviously every time we throw information away we reduce the accuracy of the model. [But] when human beings perceive the sound scene we throw away a large amount of information.’

If the researchers can create signals that only include the information picked up by the brain then they would need much less space to store and transmit those signals, in a similar way to how the MP3 format compresses sound files with relatively little noticeable difference in quality. And to do this they are developing biologically inspired models of how sound pressure at the ears is turned into an image in the brain. ‘We don’t try to mimic the brain but try to better understand it and use that as inspiration for engineering purposes,’ said Fazi.

This issue of file size is an important one to the wider success of the technology. One of the reasons 3D audio has yet to reach the mainstream, despite techniques like ambisonics being around for decades, is the vast amount of computing power it takes to render the files in real time to whatever speaker layout the listener happens to be using. But processors have finally reached the high-speeds needed to produce 3D sound at a reasonable cost, which explains some of the recent advances in the field.

The other barrier to the spread of 3D sound has been industry takeup, limited by a fear the technology is too expensive for consumers and the lack of an agreed standard format. So Dolby’s decision to roll out the Atmos system, encouraged by the movie industry’s desire to improve the cinema-going experience in response to piracy, is a big deal. However, just as 3D video has its detractors, there is a chance the audience might not buy into. ‘It is definitely an important milestone,’ said Fazi. ‘If it is not well received then obviously it might impact the whole 3D audio world … We will see if this will actually lead to a 3D revolution in the audio world or will be just an attempt and will die out again.’

But even if some find 3D audio to be a gimmick, the trend in the movie world is towards a greater number of ways to watch a film, whether with 3D glasses, giant IMAX screens, or the 48 frames per second format also pioneered by The Hobbit.

And 3D sound is another option for filmmakers and audiences, said Dolby’s Julian Pinn. ‘If we can allow content creators, whether they’re using a sonic device or a visual device, to bring more of an immersive experience to the audience then that’s just one more tool in their armoury to tell the story.’

Home sound systems

One of the great advantages of both object-based and ambisonic 3D audio systems is that the sound is rendered for whatever speaker setup the listener is using, although the level of immersion is likely to improve with more speakers. This means the technology may find its way into people’s homes more quickly than previous advances such as the 7.1 system for Blu-ray players, which requires consumers to buy a new set of speakers and arrange them in a particular layout. But it will still require the perfection of complicated spatial audio algorithms and the creation of standard formats.

One potential interim alternative could come from UK firm Cambridge Mechatronics, which is developing a single speaker array that can turn ordinary stereo (or the more effective binaural sound) into a representation of a 3D sound field around the listener. The Dynasonix projects two sound beams to a listener’s ears, creating the illusion that the signals are coming from separate speakers. Using motion-tracking technology, the device can follow and project to up to six listeners at a time, using additional noise-cancelling signals so each user can only hear their own sound beams.

This article originally appeared on The Engineer.

Putting data recovery engineering to the test

I decided to take some anger out on an unsuspecting hard drive in order to put the latest data recovery engineering techniques to the test.

Getting the high-speed freight debate back on track

Source: Network Rail

The debate over high-speed rail rumbles on with much of the noise but perhaps not enough of the velocity of the trains that provoke such heated arguments.

As we approach the environmental consultation for HS2, which could see changes to the design of the project, some of those worried about the impact the scheme could have on the countryside are focusing more on persuading government to change the route rather than opposing high-speed rail outright.

Action group Conserve the Chilterns and Countryside, for example, want the trains to start at Heathrow and pass through a tunnel under the Chilterns, rather than cutting through the hills directly from London.

But there are still some relatively high profile figures including MP Cheryl Gillan and actor Geoffrey Palmer arguing that Britain doesn’t need high-speed rail and that we could simply upgrade existing lines instead. (Gillan has previously said she was in favour of high-speed rail in a different location but this week called for the government to invest in the current network instead).

It has to be said it’s impressive how quickly those with homes in the Chilterns can become experts on Britain’s railways, helpfully bringing to light numerous scraps of evidence that have informed their carefully made decisions.

Proponents of high-speed rail in search of counter arguments (or those just looking to hear all the facts before making their minds up) may wish to look again, therefore, at the case for using HS2 to increase Britain’s rail freight capacity.

According to consultancy WSP group, moving freight to a freed-up West Coast Main Line (WCML) could take 500,000 lorry journeys off the motorways a year. This, they say, could lead to savings of over 3m tonnes of CO2 emissions and environmental benefits worth £1.3bn over 60 years.

Rail freight is on the rise as major companies such as Tesco and Sainsburys choose to use trains rather than lorries to transport goods long distances in order to cut costs and reduce their carbon emissions. The total amount of freight moved by train in 2011-2012 grew by 10 per cent compared to the previous year, the highest level since before the recession. And rail freight is predicted to have doubled by 2030.

But the case for freight hasn’t exactly been at the forefront of the HS2, which instead has focused on increased passenger capacity and carbon savings by encouraging fewer people to drive or fly. Prof Roger Kemp, professional fellow of Lancaster University and the Royal Academy of Engineering, said his submission to the government’s high-speed rail consultation largely discounted freight for two reasons.

‘Firstly the government plan talked about releasing slots on the conventional line for additional passenger trains,’ he told The Engineer. ‘If you run 12 trains an hour to Milton Keynes, there is unlikely to be much space left for freight.’

‘Secondly the traffic relief on the WCML will initially be on the Euston – Rugby section. It is difficult to see how much freight traffic would use this part of the route, without a lot of additional infrastructure.

‘Traffic flows like supermarket deliveries into London from warehouses in Milton Keynes have to use lorries for the last few miles – would companies really want to put stuff onto trains for 40 miles and then open a new distribution depot in the high-cost London area to tranship onto lorries for the last five?’

However, WSP’s head of rail planning, Ian Brooker, believes these are misconceptions and has produced the research on the potential contribution of rail freight in order to address them.

He pointed to a report from Network Rail last year that suggests four to five trains could run each hour in both directions between Rugby and Wembley while accommodating increased passenger capacity, compared to just three an hour theoretically available today.

There is also the importance of the Daventry International Rail Freight Terminal (DIRFT), which is becoming a major distribution centre for supermarkets. It lies close to Rugby on the WCML so extra capacity freed up by HS2 could make a real difference to its operations, said Brooker.

He added: ‘While the main market for rail will be supplier to depot and depot to depot, it is interesting to note that a supermarket company recently (a few weeks ago) trialled a train from DIRFT to Euston Station, with final delivery by road to their stores.’

Perhaps surprisingly, his comments on rail freight echo a report produced in September last year by a number of groups including the Campaign to Protect Rural England (CPRE). It found that HS2’s carbon benefits would increase by over 50 per cent if freed up space on the rest of the network was allocated to long-distance freight services.

If organisations such as the CPRE (not a group you’d normally expect to be trumpeting such a major countryside-disrupting development as HS2) are extolling the freight potential of high-speed rail, perhaps the debate is moving further along than it first appears.

We shouldn’t think that Britain’s railways will return to a pre-war golden era of freight transport with a depot in every town: not only do we not have the infrastructure but carbon savings are much less for short journeys.

But perhaps it’s worth giving goods transportation a greater role in the discussion than it has previously been allowed, whether the debate is on if we should build HS2, where and how to build it, and what we should with the space capacity once it’s finished.

This article originally appeared on The Engineer.

Molecular machines could lead to more efficient manufacturing

Credit: University of Manchester

This is one of the most fascinating news stories I've written.

Materials built by molecule-sized machines have moved a step closer to reality thanks to research at Manchester University.

A group of scientists led by Prof David Leigh have developed what they claim is the world’s most complex synthetic molecular machine, one that can build other molecules in a similar way to how biological compounds such as proteins and DNA are created.

The work, published today in a paper in the journal Science, could lead to the creation of molecular machines that automatically synthesise materials without the need for a complex process of chemical reactions, or even help create entirely new materials.

Molecular machines are complex arrangements of atoms that are designed to react with and manipulate other molecules, driven by the natural random movement of particles.

‘What people have done up to now is make molecular machines that can do very simple tasks like switch between different states and even do a limited amount of mechanical work, pull things a very small distance and so on,’ Leigh told The Engineer.

‘What we’ve come up with is a molecular machine that’s able to build other molecules and that’s not been done before.’

The new machine is based on a biological protein-building molecule called a ribosome, which consists of a ring-shaped molecule that includes a reactive arm and moves along a track, picking up other building block molecules and synthesising a new material.

Leigh explained that the movements of the molecules were random but that they were designed so that they could only react in the way and in the order needed to produce the new molecule.

‘The ring is moving randomly up and down the track but it can’t get past the building block,’ he said. ‘At some point the reactive arm on the ring will react with this building block and pull it off the track. Then the ring can move further down the track.’

A representation of how the molecular machine works. The movement of the real molecules is much more random.

The researchers hope that, one day, molecular machines could be used to more efficiently synthesise materials, in a similar way to how traditional manufacturing machines have enabled the more efficient production of goods.

‘Today, every pharmaceutical, every polymer, every paint, every catalyst is made by people in the lab or factory mixing together chemicals,’ said Leigh. ‘It’s lots of multi-step batch processes. Whereas with this sort of system we let the molecules do the work.’

He added that the first application of molecular machines may be to produce molecules that have not been made before, even in biological chemistry, which is based on just four types of polymer: DNA, RNA, proteins and carbohydrates.

The molecular machines themselves are gradually built up through a series of chemical reactions but Leigh described their development as a form of engineering.

‘You start with the function you want it do and then you try and design the chemical structure that will allow you to do that,’ he said.

‘Lots of different components are doing different things. For example, the ring is there to ensure the building blocks are reached in order because otherwise it could step over those blocks and react out of turn. Then we need rigid spaces between the blocks so the track doesn’t fold.’

‘Different parts of the machine have different functions, and designing the parts so they don’t interfere with the other parts is very challenging … We frequently found many times along the way that different parts of the structure were compromising another part.’

The next challenge will be to develop machines that can build molecules from a similar number of blocks to those used to make proteins – around 30 to 40 as opposed the four achieved so far.

This article first appeared on The Engineer.

Radio appearance: laser weapons, flexible tablets and modern airships

My latest appearance on Monocle 24's The Briefing, discussing weaponised lasers, flexible tablet computers at CES, and 21st century airships.

How a computer game could radically alter manufacturing

I'm used to explaining difficult concepts, whether it’s nuclear fusion or spintronics (actually I’m still not sure about that one). It helps that we have a receptive and enthusiastic audience and are tackling subject material that is usually instantly exciting.

But what if you had to explain something with less obvious appeal to people who think you might be wasting their time, for example, a complex new manufacturing business model to a group of sceptical bean counters? It’s probably not a conversation you’d want to have at a dinner party.

The answer to this might be to make the explanation into a game, according to one research group at least. Make the process fun, entertaining and engaging, and the audience might be more likely to understand and remember the concept, and perhaps even become more enthusiastic about it.

A team led by Aston University Business School are about to do just this by starting a five-year research project on the gamification of explaining servitisation. Now comes the bit where I explain what this boring and complicated-sounding concept actually is.

A product service system (PSS) is a business model where a firm offers both products and services. Rolls-Royce, for example, is well known for earning around 50 per cent of its revenue through service and support contracts, providing things such as maintenance and advice to customers that also buy its goods. Simply put, servitisation is when a straightforward manufacturing company adopts this model.

Particularly in developed marketplaces and economies, servitisation offers companies a chance to make more money than they would simply by selling products and competing against other manufacturers. Described like this, it sounds rather simple and very attractive. But making it a reality is a far more complex procedure with many barriers, and so servitisation of manufacturing firms has been slow.

Prof Tim Baines of Aston University argues that one of the biggest barriers to adoption of PSS is just explaining how the process of servitisation works. ‘To try to get those ideas across to someone in a manufacturing company in five or 10 minutes in a way that makes sense to them is quite challenging,’ he says.

This is where he believes gamification could come in. This is another slightly off-putting piece of jargon that basically means turning a process into a game. It’s not a new concept but has found growing popularity in recent years thanks to the growth of the internet and smartphones. There are any number of websites and apps that encourage you to do something by making it a game and rewarding you in some for participation.

For example, if you want to get fit but struggle to find the motivation, an app on your phone can monitor your progress to give you encouragement, telling you how many calories you’ve burnt or giving you badges for completing certain levels. One app even asks you to image you’re being chased by zombies and the only way to escape them is to run to a certain place.

But how will this work for explaining servitisation? Baines is planning to work with the Serious Games Institute at Coventry University and Sheffield’s Advanced Manufacturing Research Centre to create a computer simulation of a business adopting PSS. Companies, including Ford and Xerox, will then be brought in to test the game. ‘One of the big barriers is understanding, getting across the basic ideas and the language used, an appreciation of what it can actually mean,’ says Baines.

‘We’ll create a demonstration first of all so that we can communicate to the gaming community what we’re trying to do. The big hurdle is translating between these two communities, explaining to the gaming community what it is that we’re trying to model and them explaining to us what makes an engaging game. We’ve got to try to find the middle ground and from that we’ll create the basics of the game.’

It would be easy to write this concept of gamification off as a fad or a buzzword. For one thing, it doesn’t sound like the most fun idea for a game but, then again, there have been whole series of popular computer games designed around simulating real-life industries (Sim City, for example). And this won’t be the first time games are used to explain manufacturing concepts. Team games have been used before to demonstrate and introduce Western manufacturers to the Japanese-originated ideas of lean manufacturing.

Perhaps it will take more than a computer game to persuade companies to adopt dramatically different business models, but Baines hopes the game will do more than just change individual’s minds. ‘I would like it to be something quite pervasive that people inside the organisation become aware of and have a go at it, and for the top managers to hear about it not just from academics but also from people within the organisation who get to know about this thing called servitisation from playing the game.’

The game will also serve as a way for academics to further study servitisation so they can better understand the barriers to adopting PSS when it is attempted by real companies.

With gamification spreading even into business management techniques, it’s interesting to consider how else it could be used in manufacturing or other parts of the economy. Perhaps games could become a more common sight at work, motivating people to complete tasks or reach certain levels of achievement. On the other hand, you could argue we already run such a reward system. It’s called getting paid.

This article first appeared on The Engineer.