The diadochokinetic (DDK) rate is a measurement that speech-language pathologists (SLPs) can make. These professionals help people with communication problems. They can use the DDK rate to assess, diagnose, and treat speech and language problems. The DDK rate is also known as the “Fletcher time-by-count test of diadochokinetic syllable rate.”
The DDK rate measures how quickly you can accurately repeat a series of rapid, alternating sounds called “tokens.” They’re designed to test how well you can make sounds with different parts of your mouth, tongue, and soft palate. The tokens contain one, two, or three syllables, such as:
The DDK rate is a measure of the repetitions of sounds within a designated amount of time. For example, your test results will show how many seconds it takes you to repeat a token 10 times.
Established DDK-rate norms exist for each year of age throughout childhood. Norms for adults with various underlying conditions also exist. Experts have developed an index of comparative norms through clinical trials. The process of perfecting the index continues today.
Your SLP may use other diagnostic tests, along with the DDK rate, to assess speech and language problems that you may have.
Your doctor may refer you to an SLP if you have problems with the following types of skills:
- oral motor
Your SLP can use the DDK rate to help determine the severity of your communication problems, their underlying cause, and the best course of treatment.
Multiple parts of your body control or affect your ability to speak, including the:
- cerebellum, or the bottom back portion of your brain
- central nervous system
- muscle and bone structures in your face, mouth, and throat
Conditions that can affect your speech and language include:
- neurological disorders, such as a stroke or brain injury
- neurological diseases, such as cerebral palsy or muscular dystrophy
- birth defects, such as cleft palate
- head, neck, or mouth cancer
- impairments after surgery
Your SLP can use the DDK rate to detect specific speech variations associated with different underlying conditions. Common variations and associated disorders include the following:
- Ataxia is abnormal and uncoordinated control during voluntary movements that may affect your arms, legs, fingers, and hands, as well as speaking and swallowing. It occurs due to damage to your cerebellum or a defective gene.
- Dysarthria is a motor speech disorder that causes slow or limited movement of your mouth, face, and respiratory system. It’s often a result of stroke or other brain injury.
- Childhood apraxia of speech is an uncommon speech disorder in which your brain struggles to plan speech and control your mouth muscles. It can be caused by a stroke, brain injury, genetic disorders, or unknown factors.
- Aphasia is a disorder marked by speaking in short phrases that make sense but are produced with great effort. It occurs due to damage to the left hemisphere of your brain.
- Oropharyngeal disorders cause difficulties in swallowing. They usually result from throat damage, which can occur due to throat cancer and subsequent surgeries.
Your SLP may also use the exercises used to measure your DDK rate during speech therapy sessions to help improve your speaking skills.
Your SLP can usually measure your DDK rate in a single session, lasting about 30 minutes. They will administer a series of carefully timed tests and score your results.
During each test, they’ll ask you to produce a different sound or combination of sounds. For example, they may ask you to say the “a” sound 20 times very quickly. Then, they may ask you to repeat the sound, starting at a whisper and getting louder. Before each test begins, your SLP will demonstrate the sounds. You can then practice making the sounds several times.
Your SLP may also use other tests of oral mechanisms, such as singing to test your perceptual ability or blowing through a straw submerged in water to test your breath control.
For people who have brain damage and for children, the SLP may use familiar words like “patty-cake” or “buttercup” in place of nonsense syllables.
Your SLP will compare the results of your test to standard normalcy measurements, using the DDK rate system. For example, a typical 10-year-old produces 20 repetitions of the syllable “puh” in 3.7 seconds.
Your SLP will use any deviations from the standard normalcy measurements to assess and diagnose your condition. Ask your SLP for more information about your specific results, diagnosis, and treatment plan.
If you’re experiencing speech or language problems, your SLP may measure your DDK rate by asking you to repeat certain sounds during a timed test. The results can help them assess the severity or your speech or language problems, diagnose the underlying cause, and prescribe appropriate treatment.