Stuttering Severity Instrument - 4th Edition (SSI-4)

Stuttering Severity Instrument - 4th Edition, SSI-4, What is the SSI-4 assessment? How long does the SSI-4 take to administer?

Stuttering Severity Instrument - 4th Edition (SSI-4) is an assessment used to examine stuttering or the interruption in the flow of speaking, and is the most common fluency disorder.

ASHA describes that stuttering presents as specific types of disfluencies, including repetitions, prolongations, and blocks.

Research shows that this speech disorder can significantly impact an individual’s quality of life, affecting areas such as education, employment, anxiety, and depression. Assessments tools can help speech-language pathologists effectively assess and plan for treatment for individuals with fluency disorders. One of these tools is the SSI-4.

What is the SSI-4 assessment?

The Stuttering Severity Instrument - 4th Edition (SSI-4) is a reliable, valid standardized assessment used by SLPs to measure the severity of stuttering in individuals. The SSI-4 provides valuable information about the nature of a client’s stuttering disorder, which aids in the development of individualized treatment plans.

Let’s explore the SSI-4, including its use, how to administer and interpret the test, and recommendations for using the results in treatment planning.

What does the SSI-4 measure?

The SSI-4 measures stuttering severity in children and adults by assessing various aspects of speech fluency.

The test helps determine the following areas of stuttering behavior:
  • Frequency
  • Duration
  • Physical concomitants
  • Speech naturalness

The SSI-4 has several components and subtests. These include speech samples, rating/evaluation scales, and observations. This provides the SLP with comprehensive information about the individual’s stuttering patterns and severity. SLPs can refer to the examiner’s manual for scoring and interpretation guidelines.

How do you count stuttering events on SSI-4?

Frequency of stuttering

The frequency of the individual’s stuttering is calculated by following the computation in the examiner record form. The %SS (percentage of syllables stuttered) is equal to the number of stuttering events divided by the number of syllables (in the speech sample), multiplied by 100.

The SLP converts the %SS to a Task Score through a table on the record form.

Duration of stuttering

This is the average length of three longest stuttering events, which are timed to the nearest 1/10th of a second. The examiner uses a table on the record form to convert the duration to a scaled score.

Physical concomitants

The examiner clinically observes different types of physical concomitant behaviors and rates each one on a scale from 0-5, according to how distracting or severe they are.

Behaviors include:
  • Distracting sounds
  • Facial grimaces
  • Head movements
  • Movements of the extremities

By adding these numbers, the examiner obtains a physical concomitant score.

Total score

The total score measures the overall severity of the individual’s stuttering disorder. The examiner adds scores from the frequency, duration, and physical concomitants sections to obtain the severity score and percentile rank.

These are calculated using the tables within the record form. These tables also convert scores to a severity equivalent, which ranges from “very mild” to “very severe”.

Administration of the SSI-4

To prepare for administering the SSI-4, the SLP should familiarize themselves with the testing procedures outlined in the examiner’s manual.

Before administering the assessment, the therapist should gather the necessary materials, including:
  • The examiner record form and picture plates
  • A writing utensil
  • Blank paper and/or an audio recording device to record speech samples

Step-by-step procedure for administration

The examiner starts by obtaining several speech samples from the client. The examiner can transcribe these by writing as the client speaks, or obtaining an audio recording and later transcribing them.

The SLP will first determine whether the client is considered a “reader” or “non-reader”.


If the client is a reader, the examiner will ask him or her to read from the passages that match the client’s age, which serves as the first clinical speaking sample (reading task). A second speech sample is obtained using the picture plates provided.


If the client is a non-reader, the seminar obtains 2 required speech samples by presenting the picture plates in the examiner’s manual.

For both readers and non-readers, a third, optional speech sample may be obtained. This consists of a “beyond clinic speaking sample” (a speech sample obtained outside of the clinic).

When presenting the picture plates to obtain a connected speech sample, the examiner can encourage the client to describe the picture in detail by beginning with an instruction such as, “tell me what you see here”.

The examiner should time the three longest stuttering events to compute the duration. Clinical observation should be used to complete the evaluating scale for the physical concomitants section and the speech naturalness rating.

Potential challenges of administering SSI-4

SLPs should be prepared to address potential challenges during administration, such as anxiety, limited speech output, and resistance from the individual. Establishing a strong, positive rapport, providing clear instructions, and creating a safe, non-judgmental atmosphere can help combat these challenges.

Interpreting SSI-4 results

After completing the SSI-4, the examiner analyzes the scores and severity levels to gain insights into the client’s stuttering profile. This analysis is helpful in determining the most appropriate treatment approach and goals.

The severity ratings obtained on the SSI-4 can assist in setting realistic expectations for therapy outcomes.

SLPs can integrate the SSI-4 findings with other assessment tools and clinical observations to obtain a comprehensive understanding of the individual’s stuttering. This holistic approach ensures a more accurate diagnosis, and considers the presentation of stuttering in a variety of speaking situations or environments.

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Using SSI-4 in treatment planning

The results of the SSI-4 play a critical role in treatment planning for clients who stutter. They guide the SLP in selecting appropriate therapy techniques and strategies to address specific difficulties identified on the assessment.

For example, if the SLP identifies the presence of repetitions, prolongations, or blocks within an individual’s speech, this has implications for which specific fluency shaping strategies may be taught to the client in therapy. These include techniques such as easy onset, light contact, and cancellations.

The SSI-4 can be readministered periodically to monitor a client’s progress and evaluate the effectiveness of therapy interventions. Based on the results of the SSI-4, the SLP can adjust the client’s treatment plan to ensure the client demonstrates progress and that the most appropriate treatment methods are being used.

Limitations and considerations of SSI-4

As with all standardized assessments, there are some limitations to the SSI-4 that should be considered. The SSI-4 may not fully capture the impact stuttering is having on a client’s overall communication abilities and quality of life. The use of self-reporting measures or observations from family members and others in the client’s life (such as teachers) can help obtain this information for a more holistic look.

Cultural and linguistic considerations should also be made, as these can influence a client’s stuttering patterns and experiences.

Incorporating the client’s perspective and that of their family in the assessment process is critical. This can provide informative insights, concerns, and goals.

Training and professional development

Therapists can utilize resources to enhance their skills in administering the SSI-4. Online courses, workshops, and seminars that specifically focus on techniques for assessing stuttering can be used.

Participating in continuing education opportunities in the area of stuttering allows SLPs to stay current on the latest research, treatment approaches, and assessment tools.

It is critical for therapists to stay up to date on advancements in stuttering assessment tools and techniques. This allows them to complete accurate assessments and provide evidence-based, effective intervention in speech therapy.

Stuttering can significantly impact an individual’s quality of life, including social skills and emotional wellbeing. Speech therapists play a critical role in treating stuttering, starting with a thorough, accurate assessment. The Stuttering Severity Instrument - 4th Edition (SSI-4) is a reliable assessment tool that evaluates stuttering severity in children and adults.

The SSI-4 can provide a quantitative analysis of an individual’s stuttering by measuring the frequency and duration of stuttering incidences, physical concomitants, and the naturalness of the individual’s speech. This information can aid in selecting appropriate treatment strategies for therapy. Periodic re-administrations of the SSI-4 may help measure a client’s progress and the effectiveness of intervention.

Resources through TheraPlatform

SLPs can use the teletherapy and practice management software TheraPlatform, an all-in-one EHR, practice management and teletherapy solution, to complete documentation and billing for speech and language evaluations. Consider starting with a free trial of TheraPlatform today. They support different industries as well as different sizes of practices including group practices and solo practices.

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Davidow, J. H. (2021). Reliability and Similarity of the Stuttering Severity Instrument-Fourth Edition and a Global Severity Rating Scale. Speech, Language and Hearing, 24(1), 20–27.

Engelen, M. M., Franken, M. C. J., Stipdonk, L. W., Horton, S. E., Jackson, V. E., Reilly, S., ... & Eising, E. (2024). The association between stuttering burden and psychosocial aspects of life in adults. Journal of Speech, Language, and Hearing Research. DOI:

Karani TF, Mupawose A. A descriptive analysis of assessment measures on the effectiveness of a comprehensive stuttering intervention approach: A single case study. S Afr J Commun Disord. 2020 Apr 29;67(1):e1-e9. DOI: A descriptive analysis of assessment measures on the effectiveness of a comprehensive stuttering intervention approach: A single case study

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