From whenever languages were first taught, there must always have been perceptive language teachers who emphasised the training of articulation over exercises based on 'listen & repeat'.
In Victorian times, the most famous teacher of English pronunciation, Henry Sweet, emphasised silent practice to help students understand how they produce sounds. In the 20th century, the phonetician J.C.Catford endorsed this view, and devised straightforward exercises that progressively lead students to be more sensitive to their sound-making capabilities.
In 1963, Caleb Gattegno published the first results of his rethinking of language teaching, Teaching Foreign Languages in Schools: the Silent Way. In chapter 1, he explained the significance of people in a baby's environment imitating the baby. In chapter 2, he observed that different languages have different breathing requirements, and that this is important for teachers to understand.
He called his approach the Silent Way because he understood the benefits of a teacher remaining largely silent, particularly when teaching pronunciation. To support the teacher in this, he devised Word charts and a Fidel for English - and later other languages - where sounds were coded using colour. (A Fidel is an exposition of the sound-to-spelling correspondences for a language. Gattegno's first fidels were devised to help children to learn to read and write.)
In the 1970's, Gattegno added Rectangle charts that presented all the sounds of a language without the distraction of spelling and meaning.This helps to free students in their experimentation and discovery.
To commemorate the 100th anniversary of Gattegno's birth, a collective memoir was published which can be viewed online here. There are many illustrations of materials he devised for language teaching.
We, and others, have built on Gattegno's work in a number of ways. Gattegno's Fidel was organised to meet the needs of children learning to read and write their mother tongue, rather than those of foreign language learners. At PronSci, we have reorganised his Fidel and Rectangle charts to remedy this, innovating in a number of ways including our presentation of low energy 'vowel' sounds (schwa etc).
We have revised his Word charts to present the pronunciation of English for non-beginners in the language, and called these the PronSci charts. (We have also revised his Silent Way charts for beginners, and these are available for anyone wanting to make use of the Silent Way pedagogy.)
The PronSci charts are designed to be used by teachers who teach grammar, vocabulary etc using whatever approaches they have found to be effective, and who are looking for a solution to teaching pronunciation that works and can be integrated into the rest of their approach.