Karen Hopkin: That is Scientific American’s 60-Second Science. I’m Karen Hopkin.
Hopkin: Some sounds are spooky [ghostly yowl?]. Some are disagreeable [screechy blackboard? Vinyl album scratch?]. And a few are solely unsettling. [creaking door? Scream? Discordant psycho-shower-scene type music?].
However some sounds…some sounds…are like nothing you’ve ever heard earlier than…and nothing you’d ever wish to hear once more.[Sound of 2-hydroxybenzaldehyde]
THAT was the sound of 2-hydroxybenzaldehyde. And for those who’re pondering, maintain on, molecules don’t make noise…effectively, you’re proper. However that discordant nightmare was an audible soundscape that represents the chemical properties of 2-hydroxybenzaldehyde.
What’s much more eerie, is that whereas that sound could have made you wish to crawl out of your pores and skin and skitter in direction of the door, the chemical itself has an identical impact on ants. That’s in response to a examine within the journal Patterns.
Jean-Luc Boevé: The world of bugs is stuffed with chemical compounds.
Hopkin: Jean-Luc Boevé of the Royal Belgian Institute of Pure Sciences in Brussels.
Boevé: Thomas Eisner…who arrange the sphere of chemical ecology… mentioned that the bugs are…the perfect chemists on earth. And he mentioned this as a type of joke however he was completely true in saying this as a result of bugs are producing wealthy quantities of various chemical substances for various functions.
Hopkin: Together with protecting themselves and their households secure.
Boevé: Many different insect teams are producing volatiles and different compounds to defend themselves in opposition to predators.
Hopkin: Like an overwhelming fragrance, these unstable secretions waft by way of the air and irritate critters who is likely to be pondering of noshing on the bugs that produced them. Boevé, particularly, research the larvae of sawfly species, which produce completely different cocktails of chemical substances that act as a repellant, particularly in opposition to ants.
However Boevé just isn’t solely an entomologist. He’s additionally an newbie musician. And he acquired to pondering, effectively, smells transmit a sign by drifting by way of the air…and so do sounds.
Boevé: I assumed that it could be fairly fascinating to go deeper into this parallel between the notion through two completely different sensory methods specifically smelling and listening to. So the thought was to transform these volatiles into sounds. Then…to check, on the one hand, predators reacting in opposition to the volatiles with, then again, people listening to sounds that characterize these volatiles.
Hopkin: The 1st step was remodeling aroma into audio. To try this, Boevé and his colleague Rudi Giot of the Increased Industrial Institute of Brussels turned to a course of known as sonification, which interprets chemical parameters into sounds.
Boevé: The chemical parameters that we used as an example it was the molecular weight of compound, or the truth that the compound possesses or not some useful teams. By useful group I imply an alcohol group or ketone group or aldehyde group or acid group.
Hopkin: These molecular properties had been then mapped to musical qualities, like pitch and tone, length and timbre, even reverberation.
Boevé: Doing so we constructed up a library of the molecule sounds obtained by changing every molecule into one sound.
Hopkin: So acetic acid…principally a concentrated vinegar…appears like:[Acetic acid sounds]
…whereas geranial, an isomer of citral, which is a most important element of the oil in a citrus fruit’s peel, sounds extra like:[Geranial sounds]
Hopkin: Boevé just isn’t the primary to make use of sonification to transform chemical knowledge into audio waves. As early because the Seventies, geneticists had been remodeling the 4 letters of DNA sequences into tunes that had been, effectively, not precisely chart-topping.
Boevé: The sounds had been…not very good, not very wealthy. As a result of when you’ve got solely 4 tones, then the music or the sound that you simply hear are…very monotonous.
Hopkin: The insect irritants had been far more fascinating…as a result of every species produces its personal signature chemical mix. Boevé and Giot mimicked these molecular mixtures by taking the person chemical sounds and mixing them collectively on a sound board…utilizing completely different volumes to characterize the concentrations of compounds in every species’ poisonous concoction.[Locust sawfly larva sounds]
Hopkin: That’s the chemical stylings of Nematus tibialis, a locust sawfly larva. Which is heavy on the dolichodial, an important oil that some crops use as an insect repellant.[Dolichodiol sounds]
And this pungent tune helps maintain Hoplocampa testudinea, the European apple sawfly, from being eaten.[European apple sawfly sounds]
Hopkin: However that’s simply the setup. Then got here the experiment. Boevé uncovered ants to the precise chemical substances…both individually or in mixtures…and recorded how totally the predators had been repulsed by every. And for the sonified sounds…volunteers would play clips…of single molecules or mixtures…and hearken to the sounds from a pair of loudspeakers.
Boevé: Then we requested them to go backward, stroll backward till they had been at a consolation zone. And I used to be measuring, I used to be noting the space that they walked backward.
Hopkin: And he discovered that the molecules and mixtures that had been most annoying to ants had been the identical ones that, when sonified, brought about volunteers to retreat.
Boevé: And plenty of advised me that some sounds had been fairly horrifying and that’s why they went backward.
Hopkin: However Boevé isn’t in it for the scares. The correlation between a chemical’s impact on ants…and a sound’s impact on individuals…signifies that he can use sonification to review the defensive scents of latest species…or species for which it is likely to be laborious to scare up a specimen.
Hopkin: Scare up? Get it?[Blood-curdling scream]
Hopkin: For Scientific American’s 60-Second Science, I’m Karen Hopkin.[Mix of insect defense sounds] [The above text is a transcript of this podcast.]