Musical mould makes miserabilists mirthful

As the occupants of the Science Lite desk segue gently into middle-age, there aren’t many occasions where we all look at each other and say “so, that gig last night…Aaaamazing man!”

Nights out are, it pains us to say, a rarity. Creaking physiques, a growing commitment to the dying art of laziness and a default irritability tend to render us idle when the clock begins to bother the evening hours. Few things draw us out from our plump sofas and ever larger plasma screens. However, a month or so ago – we broke the mould. That is to say it was the mould that broke us. Slime mould to be precise.

The Peninsula Arts Contemporary Music Festival was to hold its tenth anniversary, and what better way to celebrate than the inclusion of a little science. The theme was biomusic – a strange and wonderful hybrid which uses biological processes to actually create, not just inspire, musical compositions. Hmmm – interesting, but no competition, surely, for a night of unbridled Grand Designs?

However, we then realised one of the performances was to be a duet between a human composer and a biocomputer based on the protist Physarum polycephalum. In other words it was a gig performed by slime mould. Within moments tickets were purchased; who, after all, could turn that down?

And we are pleased to report it was really rather magical. Festival director and musician Professor Eduardo Miranda used the mould as the core component of an interactive biocomputer, which receives sound signals and sends back responses.

The Physarum mould forms a living, dynamic electronic component in a circuit that processes sounds picked up by a microphone on a piano. Basically, once the notes are struck, picked up and fed into the circuit, tubules formed by Physarum alter them.

But it is the way they alter the notes that is the source of amazement.

“When you tell it to play back, it will scramble the notes you sent in. It may even generate some pitches that were not in the notes you played – the machine has a little bit of ‘creativity’,” says Miranda. This meant the performance really was a duet…some of the output was entirely the ‘creation’ of the Physarum – a thought which tends to warp your expectations of fungus to be honest.

It seems these tubule structures have the electrical property of a memristor – a variable resistor that changes its resistance in response to previously applied voltages. So – this means it responds differently each time a note is processed – a difference based on what note was sent through the circuit before it. The computer then played notes back to Miranda based on the input it received via electromagnets which vibrated the piano strings. 

Now, slime mould has been no stranger to the pages of Science Lite over the years, with its frankly scary abilities and quirks. It can, for example, solve maze-based tasks, map out the most efficient transport networks for a city and, strangely, it is particularly attracted to herbal sleeping tablets.

Given the performance we witnessed, is it too soon to add musician to the list of abilities of this bag of amoebae encased in a thin slime sheath? Perhaps, but one thing is certain – for us, musical mould is one of the few things which can beat a night on the sofa.

Listen to one of Professor Miranda’s compositions: https://soundcloud.com/ed_miranda/biocomputer-music