What is a fluency disorder?

Fluency refers to continuity, smoothness, rate, and effort in speech production. All speakers are disfluent at times. They may hesitate when speaking, use fillers (“like” or “uh”), or repeat a word or phrase. These are called typical disfluencies or nonfluencies.

fluency disorder is an interruption in the flow of speaking characterized by atypical rate, rhythm, and disfluencies (e.g., repetitions of sounds, syllables, words, and phrases; sound prolongations; and blocks), which may also be accompanied by excessive tension, speaking avoidance, struggle behaviors, and secondary mannerisms (American Speech-Language-Hearing Association [ASHA], 1993). People with fluency disorders also frequently experience psychological, emotional, social, and functional impacts as a result of their communication disorder (Tichenor & Yaruss, 2019a).


Stuttering, the most common fluency disorder, is an interruption in the flow of speaking characterized by specific types of disfluencies, including

  • repetitions of sounds, syllables, and monosyllabic words (e.g., “Look at the b-b-baby,” “Let’s go out-out-out”);
  • prolongations of consonants when it isn’t for emphasis (e.g., “Ssssssssometimes we stay home”); and
  • blocks (i.e., inaudible or silent fixation or inability to initiate sounds).

These disfluencies can affect the rate and rhythm of speech and may be accompanied by

  • negative reactions to speaking;
  • avoidance behaviors (i.e., avoidance of sounds, words, people, or situations that involve speaking);
  • escape behaviors, such as secondary mannerisms (e.g., eye blinking and head nodding or other movements of the extremities, body, or face); and
  • physical tension.

Children and adults who stutter also frequently experience psychological, emotional, social, and functional consequences from their stuttering, including social anxiety, a sense of loss of control, and negative thoughts or feelings about themselves or about communication (Boyle, 2015; Craig & Tran, 2014; Iverach et al., 2016; Iverach & Rapee, 2014).

Stuttering typically has its origins in childhood. Approximately 95% of children who stutter start to do so before the age of 4 years, and the average age of onset is approximately 33 months. Onset may be progressive or sudden. Some children go through a disfluent period of speaking. It is also not unusual for disfluencies to be apparent and then seem to go away for a period of weeks or months only to return again. Approximately 88%–91% of these children will recover spontaneously with or without intervention (Yairi & Ambrose, 2013).

Stuttering can co-occur with other disorders (Briley & Ellis, 2018), such as

  • attention-deficit/hyperactivity disorder (Donaher & Richels, 2012; Lee et al., 2017),
  • autism spectrum disorder (Briley & Ellis, 2018),
  • intellectual disability (Healey et al., 2005),
  • language or learning disability (Ntourou et al., 2011),
  • seizure disorders (Briley & Ellis, 2018),
  • social anxiety disorder (Brundage et al., 2017; Craig & Tran, 2014; Iverach et al., 2018),
  • speech sound disorders (St. Louis & Hinzman, 1988; Wolk et al., 1993), and
  • other developmental disorders (Briley & Ellis, 2018).


Cluttering, another fluency disorder, is characterized by a perceived rapid and/or irregular speech rate, atypical pauses, maze behaviors, pragmatic issues, decreased awareness of fluency problems or moments of disfluency, excessive disfluencies, collapsing or omitting syllables, and language formulation issues, which result in breakdowns in speech clarity and/or fluency (St. Louis & Schulte, 2011; van Zaalen-Opt Hof & Reichel, 2014). Individuals may exhibit pure cluttering or cluttering with stuttering (van Zaalen-Op’t Hof et al., 2009).

Breakdowns in fluency and clarity can result from

  • atypical pauses within sentences that are not expected syntactically (e.g., “I will go to the / store and buy apples”; St. Louis & Schulte, 2011),
  • deletion and/or collapsing of syllables (e.g., “I wanwatevision”),
  • excessive levels of typical disfluencies (e.g., revisions, interjections),
  • maze behaviors or frequent topic shifting (e.g., “I need to go to...I mean I’m out of cheese. I ran out of cheese and bread the other day while making sandwiches and now I’m out so I need to go to the store”), and/or
  • omission of word endings (e.g., “Turn the televisoff”).

Cluttering may have an effect on pragmatic communication skills and awareness of moments of disruption (Teigland, 1996). For example, individuals who clutter may not be aware of communication breakdowns and, therefore, do not attempt to repair them. This results in less effective social interactions.

There are limited data on the age of onset of cluttering; however, the age of onset of cluttering appears to be similar to that of stuttering (Howell & Davis, 2011). Individuals typically aren’t diagnosed or do not start treatment until 8 years of age or into adolescence/adulthood (Ward & Scaler Scott, 2011).

Cluttering can co-occur with other disorders, including

  • learning disabilities (Wiig & Semel, 1984),
  • auditory processing disorders (Molt, 1996),
  • Tourette’s syndrome (see Van Borsel, 2011, for a review),
  • autism (see Scaler Scott, 2011, for a review),
  • word-finding/language organization difficulties (Myers, 1992), and
  • attention-deficit/hyperactivity disorder (Alm, 2011).

Speech clarity and fluency may temporarily improve when the person is asked to slow down or pay attention to their speech. These should be considered during differential diagnosis but should not be the sole therapeutic strategies.