A new fascinating study from Oxford University scientists has proven that taste and sound are intimately linked, and that most of us make these "crossmodal" associations all the time without giving it much thought.

For the study, the researchers used a commercially available aroma kit which is designed to train amateurs in the fine art of wine description. The idea was to use the kit to prove that aromas evoke musical tones. More from MSNBC:
Thirty people sniffed various samples (like almond, apple, smoked, hay, cedar, caramel). Then they had to choose from a standard database of notes played by four types of instruments (piano, strings, woodwind, brass) in a range of pitch. A subset of the test participants were blindfolded because darker colors tend to be associated with lower pitch, and since some of the odor samples had a dark color, they didn’t want to screen for visual bias.

Blindfolded or not, significant associations emerged. Few subjects linked brass with blackberry, for example, but many associated it with piano. Hardly anybody connected piano with musk, but many linked it to brass. Fruit odors were consistently associated with high pitched notes. That confirmed an earlier study by Crisinel and Spence showing that sweet and sour flavors were also associated with high pitched notes.

This effect apparently works the other way, too. Another scientist recently asked different musicians to play pieces of music with adjectives like “bitter,” “salty” and “sweet” in mind. Though the musicians could play whatever they wanted, consistent patterns emerged.
Extreme cases of this link is known as synesthesia, a rare numerological condition in which certain people can actually see numbers or sounds in color. This latest study is the first to scientifically validate the crossmodal link between taste and pitch.