Hofstra Horizons Research

Working to Advance Stuttering Treatment

Jason H. Davidow, Ph.D., Assistant Professor of Speech-Language-Hearing Sciences


“When John was in junior high school, the teacher gave a quiz, in one of his classes. After completing the quiz the students handed their papers to the student across the aisle to be graded. When his paper was returned, John found that he had received a grade of 95. The teacher went around the room calling on the students to stand and give their score. John eventually stood and immediately felt that he wouldn’t be able to say his grade of 95. He quickly considered saying ’85.’ But that number seemed too daunting also. He thought for a moment, quickly said ’75’ and took his seat.”
— Manning, 1999, p. 124

This is not an uncommon predicament for persons who stutter (PWS), as many have gone to great lengths to avoid stuttering moments. As someone who stutters, I have experienced several moments when my inability to say a word initiated the “journey” to a different and undesired utterance. Although developmental stuttering (hereafter “stuttering”) is often identified by the involuntary, overt disruptions in speech flow (e.g., blocks, repetitions of sounds, syllables, and words, and prolongation of sounds), it is the covert symptoms (e.g., fear, shame, and embarrassment) that are usually the most debilitating. In addition, PWS may have secondary characteristics such as eye blinks and body twitches that produce further desire to hide the disorder. The onset of stuttering is usually between the ages of 2 and 5, so these behaviors are often ingrained from many years of repetition and can be difficult to eliminate.

The social, emotional, and cognitive tolls that stuttering can take were likely the impetus for PWS to try outrageous treatment techniques centuries ago, including cutting the frenulum of the tongue, moving to a different country, placing a fork in the alveolar arch of the lower jaw, and pressing the thumb against the chin while speaking (Klingbeil, 1939). As Van Riper (1973) wrote in regard to some of the horrific treatments used throughout history,

“… when one stutters terribly and there is no other recourse in the world, one will put up with any folly and endure anything for the hint of hope” (p. 22).

The most successful treatments for adolescents and adults who stutter include the use of fluency-inducing conditions (FICs), which are speaking styles that temporarily eliminate or substantially reduce stuttering moments.Fortunately, remediation for stuttering has come a long way since the use of those “therapies.” Preschoolers who start treatment close enough to the onset of the disorder can be rid of their stuttering, with some not even remembering that they ever stuttered. Those programs using operant conditioning principles have reported the greatest reductions in stuttering for this age group (Harrison & Onslow, 2010). The most successful treatments for adolescents and adults who stutter include the use of fluency-inducing conditions (FICs), which are speaking styles that temporarily eliminate or substantially reduce stuttering moments. The FICs that result in the largest stuttering reductions include singing, chorus reading (reading simultaneously with another speaker), rhythmic speech (aka metronome-paced speech; usually instated by producing one syllable or word per beat of a metronome), and prolonged speech (stretching out one’s sounds, syllables, and words; Andrews, Howie, Dozsa, & Guitar, 1982; Davidow, Bothe, Andreatta, & Ye, 2009). Singing and chorus reading have not been the foundation of treatment programs, but rhythmic speech and prolonged speech have. These latter two FICs have been at the center of my research, and they will be discussed further in the following pages.

Prolonged Speech

Prolonged speech treatment programs involve shaping an initially slow, prolonged, “stretchy,” and unnatural-sounding speaking style (e.g., “How are you” is produced as “H-h-h-h-o-o-o-o-o-o-w-w-w a-a-a-a-r-r-r-r-e y-y-y-o-o-o-o-o-u-u-u”) into a natural-sounding pattern produced at normal speaking rates. Other activities to transfer the treatment gains to the real world and maintain them are also included in most programs. The literature shows that treatment programs using prolonged speech have produced the greatest reductions in stuttering (Andrews, Guitar, & Howie, 1980; Bothe, Davidow, Bramlett, & Ingham, 2006), and positive social, emotional, and cognitive outcomes (Bothe et al., 2006). Therefore, prolonged speech programs can be viewed as the most beneficial for reducing the breadth of symptoms of stuttering in adolescents and adults who stutter.

Modifying Phonation Intervals

A treatment program for adults, adolescents, and school-age children who stutter that can be considered a variation of prolonged speech, and one that I completed when I was 23 years old, is titled Modifying Phonation Intervals (MPI; Davidow, 2012; Ingham et al., 2001). Whereas most prolonged speech programs have the extension of speech elements as the treatment goal (e.g., stretching out syllables or blending words together), the MPI program targets a reduction in the number of short phonation intervals (PIs). A PI, stated simply, is a measure of the duration of vocal cord vibration measured from the surface of the throat. The vocal cords turn on and off while we speak; that is, periods of vibration (or phonation) during production of voiced sounds (those that require vocal cord vibration) alternate with periods of no vibration during the production of voiceless sounds and pauses in speech. The MPI system (Ingham, Moglia, Kilgo, & Felino, 2006) records all PIs (periods of vibration) from the surface of the throat via an accelerometer. The accelerometer sends a signal to the MPI box (see Figure 1), which is connected to a computer. The hardware and accompanying software allow for the efficient collection of many PIs, resulting in the ability to display a distribution of all PIs (see Table 1). Adults who stutter produce the majority of PIs in the range of 10-1000 milliseconds during normal speaking tasks (reading, monologue, and conversation), with an average of approximately 150 PIs in 1 minute of speech during these tasks.

In addition to the idea that prolonging speech segments (e.g., producing longer vowels or syllables) can decrease stuttering, two pieces of literature provided the initial motivation for focusing on reducing the occurrence of short PIs rather than directly extending phonation, as is done in most prolonged speech programs. The first was a study by Adams and Hayden (1976) showing that adults who stutter had slower laryngeal reaction times than normally fluent controls. Subsequent studies confirmed this initial finding (Bloodstein & Ratner, 2008). The other study by Manning and Coufal (1976) provided “additional evidence that stuttering is increased during speech that requires the rapid alternation of phonated and nonphonated sounds” (Ingham et al., 2001, p. 1229). Therefore, Gow and Ingham (1992) concluded that reducing the frequency of short PIs should reduce stuttering, since speech containing longer PIs would require slower and less frequent phonation changes (i.e., the vocal cords would turn on and off less often).

Working to AdvanceStuttering Treatment

Clients performing the MPI program are taught to reduce their pretreatment short PI (usually those below 200 milliseconds) frequency by 50 percent. The computer program supplies audiovisual feedback regarding the duration of the PIs so that the speaker can adjust his or her speech pattern (see Figure 1). Early laboratory studies showed that reducing the frequency of short PIs by 50 percent resulted in the elimination, or virtual elimination, of stuttering moments (Gow & Ingham, 1992; Ingham, Montgomery, & Ulliana, 1983). A more recent treatment study (Ingham et al., 2001) reported that five males who stutter ranging in age from 18 to 28 demonstrated zero or near-zero stuttering in beyond-clinic speaking contexts one year after treatment. In addition, “all participants provided personal testimony that the treatment led to major positive lifestyle changes” (Ingham et al., 2001, p. 1241), and some participants reported “that they now always feel like normal speakers and do not consider themselves to have a stuttering problem” (Ingham et al., 2001, p. 1241). Their speech was also natural sounding (see Figure 2), which is an important outcome, as many stuttering treatment programs begin with the production of unnatural-sounding speech (e.g., robotic or a very slow and stretchy pattern). More long-term outcome data will be available in the coming years due to the recent opening of an MPI clinic at The University of California at Santa Barbara (http://www.speech.ucsb.edu/clinic/). I am also happy to report that although I did not complete the entire MPI program, my percent of syllables stuttered went from approximately 20 percent during monologue tasks before the program to approximately 0.5 percent when I ended my participation. I currently stutter on only 0.5-1 percent of my syllables.

Advantages of the MPI Program

The use of a computer and accompanying hardware to measure PIs was important for finding a replicable treatment procedure (Ingham et al., 1983). Most prolonged speech programs require the clinician to perceptually judge the accuracy of the client’s speech pattern, a task that clinicians do with questionable reliability (Onslow & O’Brian, 1998). An objective measurement of the treatment target via a computer aids in this difficult task and provides a more controlled way to modify stuttering. Clients can also connect the MPI system to their home computer, which allows them to assess the targeted speech pattern at their convenience and provides the client with control during the treatment process. This self-management has been a part of many successful stuttering treatment programs. Additionally, the goal of reducing the frequency of short PIs rather than focusing on increasing the length of speech elements (e.g., extending syllable durations) often results in natural-sounding speech early in the treatment process.

Importance of the Treatment Package

It is essential to note that in the Ingham et al. (2001) study, the reduction in the frequency of short PIs was included as part of a treatment package involving elements such as (i) the requirement of zero stuttering to progress through the treatment schedule, (ii) a self-managed, performance-contingent maintenance schedule created to sustain positive outcomes, and (iii) beyond-the-clinic speaking tasks used to ensure transfer of fluent speech to naturalistic environments (e.g., home, school, and work). It is possible that these infrastructural variables are as important as the fluency-inducing speech pattern itself (i.e., reduction in the frequency of short PIs), and they should be a part of all treatment programs that aim to reduce stuttering. One of my future goals is to integrate the entire MPI treatment package into our Speech-Language-Hearing Clinic at Hofstra University.

Phonation Intervals and the FICs

The reductions in stuttering in the previous PI literature prompted me to examine whether a reduction in the percentage of short PIs may also be completely or partially responsible for the fluency-inducing effects of several FICs, including singing, prolonged speech, metronome-paced speech (MPS), and chorus reading. We do not know why fluency results during the production of these most powerful FICs. Identifying variables that are responsible would contribute much toward the understanding of stuttering and would support the use of that variable (e.g., reduction in the frequency of short PIs) during treatment, especially if the variable can be manipulated by clients.

Data from our lab show that speakers reduce the frequency of short PIs by an average of 50-60 percent across the following FICs: singing, prolonged speech, chorus reading, and MPS (Davidow et al., 2009; Davidow, Bothe, & Ye, 2011). Although it is too early to conclude whether or not this change is the reason for fluency during these FICs, it is a first step toward such a conclusion. Future studies in our laboratory will clarify this issue. Furthermore, even if the reduction is found to not be necessary for fluency, the results from our studies raise the interesting possibility that it could be beneficial to combine two fluency inducers. For example, if future research shows another mechanism for fluency during MPS, we could combine that fluency inducer with a reduction in the frequency of short PIs to produce a resilient stuttering reduction procedure. The fact that speakers are naturally reducing the frequency of short PIs means that less learning may be necessary (than having to introduce the change) to take advantage of this fluency inducer.

Working to AdvanceStuttering Treatment

Metronome-Paced Speech (MPS)

several scholars and doctors throughout the 1700s and 1800s had suggested and/or used rhythm, specifically speaking a syllable or word to each beat of a metronome, as a treatment for stutteringA connection between rhythm and reductions in stuttering can be seen as far back as the third century B.C. by examining the treatment of Demosthenes (Greek orator). Demosthenes was instructed to speak while walking up a hill, and his footsteps may have provided a consistent beat. In addition, Klingbeil (1939), in his review of the history of stuttering treatments, noted that several scholars and doctors throughout the 1700s and 1800s had suggested and/or used rhythm, specifically speaking a syllable or word to each beat of a metronome, as a treatment for stuttering.

Methods have been developed for improving the naturalness of prolonged speech, as feedback in the form of listener-delivered (Ingham, Ingham, Onslow, & Finn, 1989) or self-administered (Ingham & Onslow, 1985) naturalness ratings and naturalness targets have been implemented into treatment protocolsBesides prolonged speech, treatments involving MPS have produced the largest change in treatment outcome variables. Unfortunately, as is the case with prolonged speech, treatments involving MPS can result in unnatural-sounding speech. Methods have been developed for improving the naturalness of prolonged speech, as feedback in the form of listener-delivered (Ingham, Ingham, Onslow, & Finn, 1989) or self-administered (Ingham & Onslow, 1985) naturalness ratings and naturalness targets have been implemented into treatment protocols (Bothe et al., 2006). Methods to overcome the unnatural sound of MPS, however, have not been investigated to the same extent. Since prolonged speech will not be effective and/or appropriate for all clients, a focus on improving naturalness during MPS, a treatment technique that has resulted in long-term stuttering reductions for many persons who stutter (Andrews et al., 1980), seems worthwhile as a clinical question and as a means of assessing the nature of stuttered and fluent speech.

A Variation of MPS

In addition to the typical one syllable or word per beat MPS, other rhythmic patterns can be used to produce fluency in PWS. Jones and Azrin (1969), for example, altered the typical production of MPS by increasing the duration of the rhythmic pulse; instead of a 0.1-second (s) pulse produced by a metronome, the stimulus-on duration was, for example, 1 s, 2 s, 3 s, and 5 s. The time between pulses, or the stimulus-off duration, was 1 s in each condition. The 1-s condition, therefore, consisted of alternating between 1 s of speech and 1 s of silence (i.e., pause) and the 2-s condition involved alternating between 2 s of speech and 1 s of silence. Group data demonstrated that percentages of words stuttered were at or near zero when participants spoke in the 0.1-s, 0.5-s, and 1-s conditions. The trend was an increase in stuttering frequency as the stimulus-on duration increased beyond 1 s. Finn and Ingham (1994) also found that stuttering levels were at or near zero up to the 1-s condition and increased thereafter.

Working to AdvanceStuttering Treatment

The rhythmic procedure used in the Jones and Azrin (1969) and Finn and Ingham (1994) studies has received little attention in the literature. This lack of attention is surprising because both papers reported large reductions in stuttering, and stimulus-on durations of 1 s to 5 s have been rated as feeling and sounding more natural than shorter durations (Finn & Ingham, 1994; Jones & Azrin, 1969). The improved naturalness with longer stimulus-on durations, coupled with the substantial stuttering reductions, has obvious treatment implications, which warrant further study of this rhythmic speaking style as a possible treatment agent.

A recent study by Davidow et al. (2011) alternated a 1-s stimulus-on duration with a 1-s stimulus-off duration. These authors found zero or near-zero stuttering with participants producing a range of stimulus-off durations between 0.77–1.17 second, suggesting that the stimulus-off duration can be shorter or longer than 1 s and still eliminate stuttering. Jones and Azrin (1969) and Finn and Ingham (1994) did not alter the pause time; that is, it was always 1 s in those studies. Several pieces of literature suggest that judges would rate rhythmic speech interspersed with stimulus-off durations shorter than 1 s as more natural than when they are 1 s or longer (e.g., Finn & Ingham, 1994; Logan, Roberts, Pretto, & Morey, 2002).

Our laboratory is presently conducting a study that expands the work of Jones and Azrin (1969) and Finn and Ingham (1994) by examining different combinations of stimulus-on and stimulus-off durations. Preliminary data show that a reduction in the stimulus-off duration improves listener-judged and speaker-judged naturalness ratings. We presently have data from three PWS, so more experimentation is needed. Data collection for 12-15 more participants should be completed by the end of the spring 2013 semester.

Working to AdvanceStuttering Treatment


The permanent elimination of, or substantial reduction in, the difficulties associated with stuttering requires a well-designed treatment program and a commitment by the client to follow the treatment schedule. Many of the fluency-inducing techniques, including prolonged speech and MPS, are not the most desirable as they take cognitive effort to maintain and can be unnatural if not enough time is spent shaping the unusual-sounding speech pattern into a normal-sounding speaking style. Many speakers would rather stutter than produce slow, stretchy speech or sound like a robot. Unfortunately, many clients do not have the time, or the drive, to adhere to current treatment programs that will result in the greatest behavioral, social, emotional, and cognitive outcomes. Therefore, we must continue to update and improve treatment techniques, such as using a computer and accompanying hardware so that clients can practice at their leisure (e.g., MPI system) and making fluency-induction techniques more natural so less time is needed to shape the pattern into natural-sounding speech. These types of efforts will hopefully allow PWS to conquer their speech difficulties and be able to “say what they want to say, when they want to say it.”


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