Rhythm Is Key to Speech Disorders

Maintaining good rhythm isn't limited to the musically inclined. In fact, a new study suggests such cadence may help stroke patients learn to speak again.

After sustaining a head injury or stroke, some people experience aphasia, a reduced ability to form words and to speak. The condition stems from damage to areas of the brain, usually the left hemisphere. For years, researchers looked at ways to help people talk again. "Singing" words through a technique called melodic intonation therapy has produced mixed results, with some people able to sing words instead of reciting them normally.

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But a team of researchers from the Max Planck Institute thought another facet of music may be responsible for positive results: the rhythm of speech. The idea is that consistent speech patterns, sung or spoken, help patients form words and phrases.

To study this, scientists focused on 17 patients with non-fluent aphasia, meaning their speech was considerably limited but not as severe as other cases. Participants, most 45 years or older, received therapy at five centers in Berlin, Germany, for the experiment. Individuals with this type of aphasia often have issues planning speech and using organs (such as the mouth and larynx) to execute sounds.

In three conditions, researchers provided therapy to participants and measured whether melodic intonation, rhythmic speech and arrhythmic speech affected success in helping patients form words and phrases. Each condition required participants to listen to recordings and try to repeat words after the speaker. The rhythmic conditions made use of a percussion beat to establish cadence.

Here's a recording of the conditions, both sung and spoken. It's in German, but you'll get the gist of the approach by listening.(Click here to hear it).

While participants responded to therapy, scientists counted how many syllables patients recited correctly.

It turns out rhythmic recordings produced the best results. People's tendency to tap their hands or feet to a given rhythm might help the brain overcome other somatic hurdles such as forming syllables with the mouth and tongue, the researchers suggest.

Most importantly, rhythm helped guide patients even if the recording featured a person speaking rather than singing. "…Our data demonstrate that what patients utter is at least as important as how it is uttered, irrespective of whether sung or spoken," the authors write. Patients, especially those with injuries of the basal ganglia, responded well to this type of therapy.

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In addition, the team found that formulaic phrases, or ones that seem more ingrained into daily speech, were easier to reintroduce to aphasia patients. For example, patients had an easier time tackling the phrase "How are you?", suggesting that a person's long-term memory, perhaps not the therapy at hand, might be responsible for such success.

Although studies with more patients are needed, the study supports that music might not account for patients' progress after all. Instead, the rhythmic beats that underlie these melodies deserve equal attention.