You already know that specific exercise will strengthen your skeletal muscles—for example leg muscles for running, football—both soccer and American football– and  arm muscles and upper body exercise for many sports, including tennis.

  What about muscles for human speaking?  Skeletal muscle is found throughout the body, attached to bones via tendons. It is also present in tongue, lips, cheeks, attached to the jaw,  the cricothyroid muscle attached to the vocal folds for voicing, the esophagus, and the diaphragm.

 “The Human Tongue Slows Down to Speak: Muscle Fibers of the Human Tongue” by Sanders et al 2013 found that the average percentage of slow Muscle Fibers (MF) in adult and 2-year-old muscle specimens were 54% compared to  newborn human which was 32%.  In contrast, tongue muscles of the rat and cat have no slow MFs and macaque monkey  28% slow MFs; the MFs of rat and cat tongue are exclusively fast MFs.  Distribution in humans of slow MFs in tongue was found medially and posterially.  Special to adult human tongues  were MF-type grouping, large amounts of loose connective  tissue and short MF branching.   Relatedly by way of explanation for the similarity between  percentage  of  slow MF  for two-year-olds and adults,  by two years of age, human toddlers have been vocalizing (crying) since birth, babbling often since 6 months of age and speaking words for up to a year—largely through employing the same muscle structures they used for feeding.  But the movements and stiffness or tenseness of  these muscles, the tongue and lip muscles, for example, are different  for speech compared to the suckling from birth. 

An old adage: if you want to strengthen the muscles for an activity, say bicycling, swimming, or “whatever,”  then do that activity.  Such is the same for human speaking and muscle fibers in the tongue, especially. 

The importance of slow MF tongue muscles for North American English speech is that of the 25 consonants,  17 have a lengthened duration (slow consonants), and out of 14 vowel sounds,  10 vowel sounds have a lengthened duration — so it stands to reason that production of these 24 English speech sounds are associated with  using slow MFs (also called slow twitch muscles).   The lengthening or longer duration of specific English consonants and vowels can be measured via acoustic analysis (Johnson, 2000), and the need for 2^nd formant change for “long vowel” production is likewise well documented.   By way of contrast,  consonant and vowel sounds for many other languages have significantly shorter durations compared to North American English speech.  (Spanish and Japanese have been described as the fastest spoken languages in the world with all or virtually all consonants and vowels spoken quickly.)

Positioning or placement of the tongue and tongue shape, are critical for accuracy of speech sounds recognition by listeners.   For example, the Spanish and other spoken languages such as Mandarin  produce “f” and “v” sounds with a short duration via the action of pushing air through partially open lips.  For North American English, the “f” and “v” sounds are prolonged—thus likely physiologically using slow MFs for the jaw  which holds steady the position of the lips with the position of upper teeth resting on lower lip)  to allow a more prolonged push of air and air friction through the lips, and prolonged voicing for the “v” sound via action at the vocal folds via the cricothyroid muscle.

Two forms of muscle movement (loading the muscles) have been identified to “grow” slow MFs and fast MFs (aka slow twitch muscles and fast twitch muscles, respectively).    One is lengthening the muscles and the other is isometric action (stiffening or tensing the muscles).

Lengthening movement forward of the human tongue is used for specific English consonants and vowels.  For example, for accurate articulation for the North American “L” consonant sound, pushing the tongue forward to touch the lower lip and holding it there makes for the producing a “L” consonant sound which is consistently recognized by human listeners as the “L” English sound.  For accurate recognition of  the “L” consonant sound, it must have a lengthened duration.  Based on our assessments, other positions of the tongue are less consistently recognized as an “L” speech sound, probably due to coarticulation effects from preceding and following speech sounds in a word with the “L” consonant sound.

To jump forward to answering the question first posed for acquisition of clear North American English,  muscle strengthening of the skeletal muscles of especially  the tongue, lips, jaw, and the cricothyroid muscle attached to the vocal folds  can be accomplished through two means–  accurate pronunciation of  English speech sounds in words and, as we now understand,  via muscle exercises specific to slow MFs  and fast MFs.

In the last year, our coached instruction for acquiring clear North American English speech for nonnative-born speakers of English has included vocal exercise aimed at strengthening slow MFs (slow twitch muscles) and fast MFs (fast twitch muscles)  for selected consonants and  vowels.   Those exercises have enhanced speech intelligibility outcomes, that is, measured word and speech sound intelligibility have increased substantially for those doing our coached courses.

Next time—description of specific exercises and speaking tactics during  home practice (also called, aka, direct practice) for words and sentences to grow slow MFs and fast MFs (slow twitch muscles and fast twitch muscles respectively).

Just so you know,  we have identified 14 dimensions for successful acquisition of clear North American English speech by nonnative-born speakers of North American English — from over 20 years of instruction and scientific assessment.  Success is defined as optimally efficient learning which is long lasting.  The Clear Talk Mastery method of instruction and learning is both an art and a science— the art is in getting to all 14 dimensions.  In this article, we are describing one dimension.

Be sure to check out our coached instruction- go to www.ClearTalkMastery.com and click on “Services. And be sure to check out the weekly self learning program, our proven subscription called ClearTalk Weekly—video and audio tutoring– you access 24/7 www.subscription.cleartalkmastery.com It works for people new to the admirable goal of making their English speech better for career and for life. It works for people who have done a coached course but was to rev up their accuracy.

©Clear Talk Mastery, Inc. 2023