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F: (2) Wow, this apple smells like Beethoven. Good evening, welcome to Science & Nature. Believe it or not, smells and sounds may be more associated than you think. With me in the studio is Dr. Charles Spence from Oxford University. Good evening Dr. Spence. So, what exactly are we going to talk about today?
M: Good evening, Riz. Some people tend to make weird associations between the senses. (1) When they hear, say, a piano solo for example, they might associate it with colors or smells. The condition is called synaesthesia. Synaesthesia is a phenomenon whereby a particular sensory stimulus triggers a second kind of sensation.
F: Synaesthesia, what a mouthful! It’s unique to a small number of people then?
M: Well, not necessarily. Though ordinary people can’t really smell an apple and say it’s like a piece from Beethoven, simpler associations are made by almost everybody. Most people agree that low-pitched sounds are reminiscent of large objects and high-pitched ones evoke smallness.
F: (3) Indeed, and loud sounds do seem "brighter" than soft ones. There must be a link between different senses.
M: To find out, I conducted an experiment. I recruited 30 volunteers and asked them to inhale 20 smells, apple, banana, violet and so on. After that, each of them had to click through 52 sounds of varying pitches played by different musical instruments. Finally, I asked them to identify which sound best matched the smell.
F: Did anyone find it ridiculous to take a sniff and identify the sound?
M: No, far from that, they later told me that it made sense. When I collected the data, I found that there was significant agreement between volunteers. Sweet and sour smells were rated as higher-pitched, smoky and woody ones as lower-pitched. Blackberry and raspberry were very piano while musk was strongly brass.
F: (5) Amazing. Were you able to find out the reason behind it, like some part of the brain doing the job?
M: Unfortunately, no. It’s not clear why they employ musical senses when smelling. But at least, we can say that the assumption that each sense works in isolation is wrong.
F: What is the history of Synaesthesia study? What is its significance, doctor?
M: Well, it has been studied in one way or another since the nineteenth century, although only recently has it reappeared in the limelight following a number of pioneering experiments demonstrating that it was a genuine phenomenon. Currently there are many different aspects of synaesthesia being examined, from its possible genetic basis to how it develops in the brain. Synaesthesia is also proving to be a useful tool in investigating other psychological phenomena.
F: What about the connection between taste and hearing? It is said that in a restaurant background music should be selected according to what the customers eat.
M: I actually had a second experiment in this respect. In that one, each volunteer was given four pieces of chocolate. While they were eating two of them, the background music was a low-pitched one played on brass. When they began to eat the third and fourth one, the music was switched to a higher-pitched piano piece.
F: Let me guess, the first two pieces taste different from the other two.
M: That’s right. (4) Volunteers rated the chocolate eaten during low-pitched music as much bitter than that eaten during the high-pitched rendition. The chocolate was in fact identical. It was the sound that tasted different.
F: Maybe next time I can put less sugar in the coffee and instead listen to a piano piece when drinking.
M: In the third experiment, I asked the volunteers to identify colors from the sound they hear and the result is...
F: I’m sorry, Dr. Spence. We’ll have to leave it here. Thank you for sharing with us your experiment on synaesthesia.
M: Thank you!
F: For more information and a detailed report on Dr. Spence’s experiment you can visit bbc. co.uk/science. And that’s it from us for now. From all of us on the team, thanks for watching and enjoy your evening. Goodbye!