Impact case study database

Research by McPherson at Queen Mary has led to the development of Bela, an open source [5.1] hardware platform for ultra-low latency processing of audio and sensor signals, designed for various creative uses. The technology enables a wide variety of users (artists, designers, students, researchers, the disabled) to develop new ways of producing music and sound.

At the end of 2015, Bela was in use by around 50 researchers and artists worldwide. The number of people using Bela has since exceeded 2,000. In 2016, the Queen Mary team launched Bela to the public on the crowdfunding site Kickstarter, attracting the backing of more than 500 people and raising over GBP54,000 (1100% of their goal) [5.2]. The technology was commercialised through the Queen Mary spin-out, Augmented Instruments Ltd (AIL).

Use of Bela by the music community and industry

There are an estimated 2,500 unique users on 6 continents that have bought their own Bela boards and a similar number have encountered it through classes or workshops. The Queen Mary team studied the characteristics of the Bela early adopter community in 2017 and found a diversity of profiles and interests: technology hobbyists and independent creators; musical performers; musical instrument designers; media artists; teachers; students and researchers in fields ranging from human-computer interaction to signal processing to neuroscience. Musical applications predominate with musical instruments and synthesisers being the most common. Art installations are another frequently mentioned application. Reasons that people used Bela, included "signature features": low latency (particularly important for percussive instruments as confirmed by a user); compact size; open-source design plans; ease of getting started and support for popular open-source software tools.

Dozens of instruments have been created by Bela users and are showcased on the project blog (86 posts to date) and their own sites. There is an online forum (over 830 registered users) with spontaneous (unsolicited) public promotion of the platform by its users, and volunteer ports to Bela of audio programming languages including SuperCollider, FAUST, Csound and Pyo.

Making music more accessible to the disabled community

The Accessible Music Hackathon

In February 2016, Bela was used in an Accessible Music Hackathon co-organised with Drake Music [5.3], with the support of the British Council, to develop prototypes of new accessible instruments. Tim Yates, Research & Development Programme Leader & Associate Musician at Drake Music said “we produce bespoke instruments for individuals; they have disabilities and can’t use standard musical instruments in the standard way, so we help them to use the instruments in a way that is specific to each person. Bela is low cost and you don’t need a Master’s degree to build it. It opens up the opportunity to give access to music to people who didn’t have that before; it’s very powerful. It also opens up the possibilities to people from multiple different backgrounds to create projects and instruments that otherwise were not possible.”

There was engagement with around 50 people on the day of the hackathon with an international audience. Two projects out of the 10 that were presented at the event used Bela. Leah Zakss, Programme Manager for the British Council’s Music team in London, said that “It was amazing to see what entrants had produced in such a short period of time, and refreshing to be connected to a whole new network of people around the UK working in the field of AMT [assistive music technology]. I know that our international colleagues who visited were amazed at the innovation on display. We had a lot of fun and learned so much” [5.3].

The Haptic Baton

The Haptic Baton, created using Bela, helps visually impaired musicians to perform live within a group. Motion sensors inside the baton send data to a micro-controller, which wirelessly transmits the movement data as vibrations, felt by the musicians through wearable wristbands. Musicians can wear the wristbands and feel the baton movements as haptic vibrations rather than following the visual cues of the conductor’s baton [5.3].

Strummi

In 2018, Jacob Harrison and Robert Jack (McPherson’s PhD students) created Strummi, a simplified guitar-like instrument that uses Bela's low-latency audio processing to maintain the richness of strumming real physical strings while simplifying chord selection into a series of buttons. Strummi, shown in use in Figure 2, emerged from a collaboration with the OHMI Trust, a charity devoted to music-making for physically disabled individuals [5.6]. OHMI stands for ‘one handed musical instruments.’ Stephen Hetherington, founder of OHMI, writes “Our primary task is to adapt traditional instruments or create sophisticated emulators, such that the instrument itself is not a barrier to full inclusion and potential virtuosity. By making the guitar fully playable with one hand, Strummi offers the real opportunity for many thousands of disabled people in the UK to play music for the first time.”

Figure 1: Left: Bela Mini unit; Right: Strummi in use.

Strummi is now in use in the OHMI national teaching programme, the OHMI Music-makers, which provides one-to-one music lessons and ensemble groups. It makes around 50 school visits per year. Lessons are given in school time so children learn alongside their peers. After launching in Birmingham in 2015, the project was rolled out in Surrey and Hampshire in 2016.

A new musical instrument for stroke patients in rehabilitation

A musical performance including Robyn Steward, who used Bela in a foot pedal called ‘Barry’ connected wirelessly to her trumpet, took place at the Barbican in 2019. This event was attended by 20-30 people. It was hosted by AIL and featured in an article in The Guardian (print readership: 3,600,000; circulation: 111,953; monthly browsers: 25,100,000) [5.7]. This led to a GBP25,000 grant to Queen Mary from the Chelsea and Westminster Hospital Foundation to create a new instrument for stroke patients “that could be used by patients at various stages of their rehabilitation, offering both accessibility and challenge, in a design small enough to potentially be used by patients in bed - and all this while adhering to hospital infection control protocols”, according to Andrew Hall, Music and Sound Research Consultant at Chelsea and Westminster Hospital NHS Foundation Trust [5.8]. He wanted to use Bela, as it “was clearly the optimal starting point for the design of the instrument, due to its low latency and ease of implementation.” He went on to say, “So far prototype trials with 4 patients, and interviews with 2 patients and 7 clinicians have illustrated the various ways of approaching the instrument, from picking out melodies to strumming the surface like a guitar, but they have also highlighted patients’ appreciation of the instrument’s aesthetic, describing it as ornamental or resembling an old board game.”

Use of Bela as an educational resource

Bela has been adopted for teaching in over 20 universities spanning Europe, North America and Australia. It is a core part of the curriculum of a new cross-university Master's in Music, Communication and Technology (University of Oslo, NTNU Trondheim). According to Bernt Isak Wærstad, Academic Programme Director for the Live Electronics program at the Norwegian Academy of Music and co-founder of the COSMO Project (an open source project devoted to making a hardware and software framework for designing and building embedded standalone Csound instruments to use on stage), “the hardware solution was both more compact (one board sitting on top of a single board computer) and possible for anyone to order readymade (unlike our current custom designed hardware). The convenience of the browser based IDE made it possible for a much smoother and easier workflow making it easier for less advanced users who are not very comfortable operating a system through a terminal. Finally, the low latency and real-time kernel made this system both more snappy and much more stable in performance compared to the Raspberry Pi.” [5.5].

The Bela team has also released a series of 14 free public YouTube videos on C++ audio programming with Bela, ranging from 22 to 53 minutes long, which as of 1 October 2020 have a combined total of 14,494 views and 699 likes [5.9]. Comments on the videos are very positive, including: “This entire course has been utterly fantastic, thank you so much for putting something so professional together and making it free. I really love what you and the entire Bela team are doing” and “Amazing material! I love how well the hardware and software has been designed. Can't wait to get one and get through the whole course.”