Both groups judged auditory patterns accurately about 85 percent of the time, the researchers report in the August 5 issue of Current Biology. On the visual trials, nonsynesthetes’ judgments fell to nearly chance levels, a result that corroborates other research showing that most people are better at judging auditory patterns than assessing visual patterns. In contrast, synesthetes—who reported hearing sounds such as beeps or taps in time with the visual signals—distinguished matching from nonmatching rhythms 75 percent of the time.

I was just thinking that migraine sufferers are sensitive to bright lights. I wonder if there can be synesthesia of frequencies that aren't audible, like extremely high pitches. but which can still affect us.