I am sure you have often marvelled at the night sky. The endless, unexplored vastness of other solar systems and galaxies is hard to see and difficult to imagine. Yet more astronomers are bringing these far-flung worlds closer by converting cosmic signals into sound.
Through a process called sonification, scientists construct a soundscape to represent data from telescopes. For example, this is the sound of the black hole star system V404 Cygni
The firework at the beginning is the sound of the black hole, the crashing waves are light echoes (bursts of energy that bounce off nearby gas and dust), and the random notes are individual stars. Although sonification is not a new technology, a growing number of astronomers are recognising the benefits of ‘listening’ to the universe.
The first recorded case of radio astronomy was in 1932. US physicist and radio engineer, Karl Guthe Jansky was trying to find the source of static in overseas radio communications. His rotating antenna picked up a consistent ‘hiss’ throughout the day. After ruling out all other possibilities, Jansky discovered that the sound was radio waves coming from the centre of the Milky Way! However, it was only later that scientists began listening to their data on purpose. For example, in the 1980s, Donald Gurnett and his team at the University of Iowa used sonification to identify problems affecting the Voyager 2 mission around Saturn. When the radio signals from the spacecraft were converted into audio, they heard sounds ‘resembling a hailstorm’. This turned out to be electromagnetically charged micrometeoroids the size of a grain of dust, which were bombarding the probe. In 2004, Gurnett converted data from the Cassini mission around Saturn into sound. He discovered lightning on Saturn as well as radiation emitted by electrons in the planet’s auroral zone.
This is the sound of lightning on Saturn
Sonification trumps visual data analysis in many ways. By simply using their ears, scientists can sift through large volumes of data that they would otherwise struggle to process and even pick out signals they might have missed. This is because our auditory systems can identify patterns and extract meanings that our visual systems cannot. Furthermore, according to Anita Zanella, by using sound, scientists can portray up to 12 dimensions at once! These include parameters such as pitch, frequency, rhythm and spatialisation. Sonification helps to pick out weak signals in lots of noisy astronomical data: humans can focus on several sounds at once whilst filtering out unnecessary background noise. This is called the cocktail party effect - think of how you can understand what your friend is saying in the middle of a loud party.
Although sonification is a new technique for some, Wanda Díaz-Merced at European Gravitational Observatory in Cascina, Italy, has been using it for years. Since losing her sight
as a teenager, Díaz-Merced has, with the help of her colleagues, turned all her data into sound. Sonification has helped her study gravitational waves, black holes and gamma ray bursts. For example, after listening to one gamma ray burst, she heard chirps, squeaks and rustles within the noisy data. Díaz-Merced and her team then discovered that gamma ray bursts give off energetically charged particles which are crucial to the formation of new stars.
However, there are some issues with the technology. Due to its unorthodox beginnings, astronomers working with sonification today use techniques passed down by previous colleagues or even invented by themselves. This means that methods are not rigorously tested for efficacy and are neither published nor peer-reviewed, all vital processes in the scientific canon. Furthermore, knowledge exchange is limited which can lead to many groups working on the same thing and achieving the same results – highly inefficient.
To combat this, Zanella has collaborated with the psychology department of the University of Padova, Italy to develop the first joint PhD in astronomy and psychoacoustics (how we perceive sound). The programme, starting this October, aims to find the best ways to sonify astronomical data and establish standardised methods so, eventually, standard techniques will be available to everyone!
As demonstrated by Díaz-Merced, more sonification of data improves accessibility for the blind or visually impaired. Therefore, fewer people will be faced with the challenges she was confronted with over her physics journey. As well as in academic research, sonification is being used in educational outreach. For example, British astronomer, Chris Harrison, created an audiovisual show to take into Newcastle schools. He originally tried a tour of the solar system using ‘cool sounds’, but said the children much preferred musical instruments. Each planet has a distinct pitch and instrument corresponding to their motions – Jupiter features a ‘rumbling bass trombone’.
In conclusion, the universe may be large and intelligent life may be unlikely and hard to fathom, but soon, it won’t be Ed Sheeran at the top of the charts, because we’ll all be jamming out to the carina nebula
Sound of a solar flare from Cassini mission: https://www.nasa.gov/wav/52924main_t2003_301_11.wav