Treatment Sounds: Sound Connections

Blog #14 in the Phonology Means Nothing and Other Astounding and Very Practical Facts about Speech Sound Disorders Blog Series

For more information about this series, see the Phonology Means Nothing Series welcome page.

By Ken Bleile, PhD
March 10, 2021

Speech knowledge refers to how similar a treatment sound is compared to other sounds a child makes. If you select a treatment sound only slightly different from other sounds the child already produces, you are following a most knowledge method. If you select a treatment sound quite different phonetically from sounds the child already produces, you are following a least knowledge method.

Most and Least Knowledge

A simple example may help illustrate the logic of the most and least knowledge methods of treatment sound selection.

Example: For the example, imagine a hypothetical child who can pronounce only one consonant, [b], and your choices for treatment sound are [p] or [t]. We can depict the decision this way:


p?        t?

The question is, which do you select, [p] or [t]? (Of course, you could always select both [p] and [t], but forget that choice. . . . This is just an illustration.)

Choices: If you select [p] as a treatment sound, the child learns how to make a voiceless consonant. If you select [t], the child learns to make an unvoiced consonant and a new place of production (the alveolar area). The [p] selection is the most knowledge method, because [p] differs from [b] by only one feature (voicing). The selection of [t] is the least knowledge method, because [t] differs from [b] in two features (voicing and place).

Second Example: To clarify the distinction between most and least knowledge, consider the same example, slightly modified:


p?        t?


Choices: Now you have a choice between three possible treatment sounds, [p], [t], and [s]. [p] remains the most knowledge choice with the child learning one feature, [s] is the least knowledge choice with the child learning three features (voicing, place, and manner), and [t] now is somewhere in the middle with the child learning more features than [p] but less than [s], the least knowledge choice.

Logic of the Positions

The most knowledge method is the traditional way to select a treatment sound. The method ensures that treatment proceeds in small manageable steps, reducing possible frustrations for the child (Van Riper, 1978). Historically, clinicians followed a most knowledge method when children who received services typically were grade schoolers whose speech contained one to a handful of consonant errors. Concern arose with the method when clinicians began to treat preschoolers with multiple speech sound errors. Small increments can prove time-consuming with such children. To illustrate, a most knowledge method for oral stops could require six different treatment sounds, one for each oral stop ([p], [b], [t], [d], [k], and [g]).

A least knowledge method speeds speech work by abandoning small incremental steps. To return to our example, rather than devoting the time to teach [p], [t], and [s] individually, a least knowledge method selects [s]. Through learning [s], a child learns—perhaps without being taught—a new place ([t] and [s] both are alveolar) and new voicing ([t] and [s] both are voiceless). Historically, the least knowledge method arose when clinicians began to treat children (typically late preschoolers, 3;6 to 5;0) whose speech contained multiple speech sound errors. The method is a phonological approach to treatment sound selection in the sense that it looks at sounds as belonging to sound classes.

Most or Least Knowledge?

Several considerations may aid in deciding whether a most of least knowledge method best meets your clinical needs:

1. The Late 8: Little or no difference exists between the methods with students with speech errors affecting a few isolated late 8 consonants. The issue of most or least knowledge only arises when classes of sounds are in error.

2. Stimulability: The least knowledge method often is associated with selecting nonstimuable treatment sounds. This is because the chief proponents of a least knowledge approach select nonstimulable treatment sounds. However, least knowledge and stimulability are different decisions, and a clinician can use a least knowledge method to select either a stimulable or a nonstimuable treatment sound. To illustrate, in our example, the least knowledge choice could have been a stimulable [s] or a nonstimulable one. The essential tenet of a least knowledge method is to select a treatment sound that teaches as many features as possible. Clinicians may find that with younger preschoolers (2 to 3;6), the least knowledge choices are stimulable sounds, and that the question of nonstimulable choices is more an issue with late preschoolers.

3. Developmental Norms: If you decide on a least knowledge method, you find that occasionally the least knowledge choice is a sound in advance of a child’s level of development compared to developmental norms. To illustrate, the least knowledge choice for a child aged 2;0 might be a stimulable [s], though children typically do not acquire that consonant until several years later. A true developmentalist (which most clinicians—including me—were years ago) would say do not select [s] because the child is not developmentally ready to learn it. I believe time has modified the developmental position. Today, clinicians view developmental norms as the average ages at which children typically stumble on how to make a sound, rather than reflecting developmental steps that they must follow in a strict order. Most would not penalize a child who happened to verbally stumble on [s] at 2;0 by making him wait several years to receive treatment on [s].


Van Riper, C. (1978). Speech correction: Principles and methods (6th ed.). Englewood Cliffs, NJ: Prentice-