Why is a cellist and sound artist collaborating with someone who deals with brain disorders?
Chris Chafe: I am working with neurologist Josef Parvizi on what we think is the first – certainly the cheapest – device that turns brainwaves into both music and a powerful medical tool. In the process, I am making some of the best, most exciting electronic music of my life.
What led you down this path?
CC: I have been involved in other projects where I turn data into sound, for example the output captured by underground geophones from fracking, or complex structures in synthetic biology. This is called sonification.
Humans have great auditory acuity when it comes to comparing slightly mismatched things. We’re taking inaudible brain signals and making them audible through sonification. Then we feed them to the areas in the brain that recognise patterns in music. The result is our Brain Stethoscope.
What can the device do?
Josef Parvizi: We use EEG electrodes and connect them to a computer. An algorithm written by Chris then allows us to listen in to brain activity. I specialise in treating patients with intractable epilepsy, and we need EEG monitoring to see where the seizures are coming from in the brain. The Brain Stethoscope can help us find out whether a patient is having continuous seizures.
How does it detect seizures?
JP: Many times we don’t see any particular behavioural manifestation of seizures – falling down, convulsing and so on. This can be dangerous because you don’t know what is really going on with such a patient. EEG reliably captures seizure waves because they are synchronised, very high amplitude waveforms generated by the synchronised activity of billions of brain cells.
CC: If you were just to convert raw brainwaves to an audio file, and hook up a loudspeaker, you would hear a low-frequency rumble. So we pull those signals into the more usual audio range by treating them as a modulation. It’s like photographers in a darkroom, enhancing contrasts to get at figures they want to portray.
How do you bring the patterns and variations in a recording to the fore and translate it into a more musical, listenable state?
We’ve chosen the output sound to be a singing voice, so it has a vowel quality to it – such as “aah”.
What does the brain sound like?
CC: All brain activity can be described in musical terms. A flat-line brain signal produces a dull, computery-sounding singing voice. Normally, an electrode channel has a bit of a wiggle to it and you’ll hear it modulate the pitch up and down. It modulates at a slow enough rate that we hear it as something like a vibrato or a pitch inflection.
It’s not all that unfamiliar, because of the happy accident that the speed of those undulations is in the range of the speed of the inflections you get in music. For a lot of these things, the proof is in the hearing.
Is it straightforward to use as a diagnostic tool?
JP: I asked 52 of my colleagues, medical and non-medical, to try it out. After only 30 seconds of training, they chose the correct answer about 95 per cent of the time when they heard eight clips we played to them. It shows that ears are absolutely amazing in differentiating between the sound of a seizure and normal brain activity.
Does this mean our ears are sharper than our eyes?
JP: Imagine you are in intensive care or an ambulance, and you really need to know if a person is having a seizure. Evolutionarily, ears are much more intelligent than eyes. In an emergency, we think that it is far more intuitive to hear rather than see if there is seizure activity.
What about the musical side of the collaboration?
CC: Some of the translations from brainwaves to music are producing extraordinary rhythms. It’s the music of the brain. I’m involved with free improvisation, which is often fast and has a lot of variation. Oddly, it resonates with the sounds that we’re getting from the Brain Stethoscope. It’s also very fast, and very intricate – and musically really exciting.
Will we hear music made this way in a concert hall or club?
CC: I don’t think that incorporating it into a concert will produce the fullest impact, so I’m looking for a better outlet than a one-off composition. There is a considerable cognitive load in hearing a new form of music. Experiencing and appreciating something like this may take longer than the time available in just a segment of a concert. Maybe it would take a whole concert? Or maybe it belongs online.
Can anyone use the Brain Stethoscope?
JP: Yes. You can use it for biofeedback or neural feedback, where you can put an EEG band over your head, put on headphones and listen to your own brain sounds. Then you can try to alter it by thinking, and listen to the difference.
Why is it useful to be able to hear our brain at work?
JP: That is very important for patients who suffer from neuropsychiatric disorders or chronic pain, but it can also be used as a toy by kids who are interested in playing with their own brains and, hopefully, becoming more and more fascinated by the intricacies of our brain universe.
When can we get our hands on it?
JP: We have a real-time prototype. The next phase is making the electrodes more flexible and for it to run on a mobile device. That should be by the middle of the year.
Josef Parvizi is an associate professor of neurology at Stanford University Medical Center, California. Chris Chafe is a music professor, also at Stanford
Syndicated content: Kat Austen, New Scientist