Stuttering is commonly understood as a speech disorder that manifests as part-word repetitions, prolongations, and blocks (Bloodstein & Bernstein Ratner, 2008). These are all overt speech events that carry acoustic and perceptual consequences that are available to the listener.
However, some people who stutter are adept at obscuring the overt aspects of their disorder. They can speak without revealing to their speaking partner that they are a person who stutters, effectively passing as fluent speakers. Due to the secret nature of their stuttering, they are said to covertly stutter. These individuals are perhaps the best example that, at its core, the experience of stuttering is something that is felt and experienced rather than something that can be observed and measured by the listener (Moore and Perkins, 1990, Perkins, 1990).