Ville Pulkki’s research group utilises existing techniques to develop 360-degree sound for virtual reality environments.
With the surging popularity of virtual reality glasses, many of us have had the opportunity to experience the virtual 3D world. The ongoing boom in virtual reality technology has resulted in new applications for existing techniques.
Spatial sound, typically integrated in virtual reality environments, refers to those properties of sound that result in the listener’s perception of space, containing factors such as the perceived location of the sound source. The goal is to create 3D audio for virtual reality environments that is as realistic as possible. For this, the technology must meet two criteria: It must have the ability to replicate real, recorded sonic environments and to synthesise non-existing ones. The technique must also succeed in creating these audio experiences through both headphones and loudspeakers in a way that results in the perception of natural sound from any and all directions.
‘When the sound technology for virtual reality applications is advanced enough, it will revolutionise the entire field and open up new avenues in terms of virtual travel and conferences, for example. For that, however, we still need to have transparent displays of better quality. I think this will happen within next decade,’ says Ville Pulkki, Professor of Acoustics.
‘My dream is to stand amid a noisy colony of penguins at the South Pole, with the assistance of virtual reality technology. The existing technology already allows us to record surrounding sound and image, and when we transmit this recording to a virtual reality display, we will create a breath-taking experience,’ explains Pulkki.
Surround sound for virtual reality environments
Pulkki’s work has influenced many of the sound techniques currently used in the production of motion pictures and virtual reality games. Some of the gaming applications already utilise the synthesis method developed by Pulkki for his doctoral dissertation. In 2014, Pulkki was awarded the Samuel L. Warner Memorial Medal in Hollywood for his contributions to motion picture sound technology.
The method enables the localisation of individual sources of sounds in the desired direction via both loudspeakers, and also headphones as long as the listener’s head movements can be tracked accurately. Today, this technique is integrated into the MPEG-H and DTS:X audio formats and commonly applied in the reproduction of virtual reality sound environments in Sony Playstation VR.
Pulkki developed another solution for spatial audio reproduction in collaboration with Juha Merimaa (D.Sc.(Tech.)). In the technique, sound is recorded from different directions with four microphones. The recording is analysed to estimate the sound directions, and this data is then used to enhance the reproduction of the sound via either headphones or loudspeakers. Originally developed as a tool for teleconferences, the technique was sold to the German research institute Fraunhofer IIS in 2007, and since then it has also been applied to virtual reality environments. Already demonstrating it to potential customers, Fraunhofer IIS may be able to bring the technique to the market in the next few years. Simultaneous reproduction of surround sound and video provides a powerful ‘I’m there’ experience.
‘Our method creates a more realistic sensation than the techniques based on more conventional processing methods. The downside is the heavy computations required by the method. Fraunhofer IIS has, however, already succeeded in getting the technique to work in a smartphone simultaneously with displaying the video,’ says Pulkki.
Professor Ville Pulkki
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