Amusia...continued

Previous studies pertaining to British and French-Canadian amusics showed that about 30% of amusics have difficulty discriminating between statements and questions depending on the intonation based on the final rising (question) or falling (statement) pitch glide .

Patel et al. re-examined prosodic judgments in British and French-Canadian amusics by asking participants to make same vs. different judgments for two different kinds of stimuli. The first set of stimuli consisted of statement-question pairs, where the two sentences were exactly similar except for the last part where the intonation changed depending on whether the sentence was a statement or a question. So, a question would have a rising pitch glide on the last word (e.g. He likes to drive fast cars?) whereas a statement would have a slight dip (e.g. He likes to drive fast cars.). The second set of stimuli consisted of focus-shift pairs, where although the two sentences were similar, the intonation differed depending on the location of the salient pitch accent (e.g. Go in front of the bank I said. vs. Go in front of the bank I said.).

Their results indicated that some amusics had difficulty discriminating statement-question pairs. However, these amusics did not have any difficulty discriminating between two sentences in a focus-shift pair. This suggested that while amusics could detect pitch movements in speech, they had difficulty detecting the direction of pitch movements (based on their difficulty in judging the rise or fall in pitch glide on the same word in the statement-question pair).

These results are also consistent with results from a previous study conducted by Foxton et al., where British amusics were asked to judge the direction of a pure tone pitch glide. Foxton et al. manipulated the glide rate by keeping the glide duration constant and by increasing or decreasing the size of the glide. They found that amusics had difficulty when the pitch glides were smaller (the glide rate was lower). On average, the threshold for accurate direction judgment in amusics was about 2.2 semitones compared to 0.1 semitones in controls. When expressed as glide rates, these numbers correspond to 22 semitones/second vs. 1 semitone/second. These results offer various avenues for experimental and computational exploration.

Currently, work is being done on amusic prosody judgments in tonal languages such as Mandarin Chinese. It will be extremely interesting to see how work in this area progresses.