English pronunciation is famously inconsistent with its spelling — and there's a specific historical reason for it, not just accumulated randomness.
Between roughly the 1400s and 1600s, English underwent a major, sweeping change in how long vowels were pronounced — the Great Vowel Shift. The problem: much of English spelling had already become standardized (partly due to the spread of the printing press) before the shift finished, freezing many spellings in place while the actual pronunciation kept changing underneath them. This single historical event explains a large share of why English spelling and pronunciation don't line up today.
Words like "knight," "island," and "debt" carry letters that are no longer pronounced at all — remnants of earlier pronunciation or, in some cases, spelling changes made to visually resemble Latin, rather than reflecting how the word was ever actually said in English.
English rhythm is "stress-timed" — stressed syllables occur at roughly even intervals, with unstressed syllables compressed to fit, rather than every syllable taking equal time (as in "syllable-timed" languages). This is a major part of what gives spoken English its distinctive rhythm and makes some non-native accents sound different even with correct individual sounds.
Largely because of the Great Vowel Shift, a major change in vowel pronunciation between roughly the 1400s and 1600s that happened after much of English spelling had already become fixed, freezing old spellings alongside new pronunciations.
Many reflect older pronunciations that have since dropped (as in "knight"), while others were added later to visually resemble Latin spelling rather than to represent any sound actually spoken in English.
It means stressed syllables occur at roughly even intervals, with unstressed syllables compressed to fit around them, rather than every syllable taking equal time — a major contributor to English's distinctive spoken rhythm.
That's the plan, matching the audio-based approach already used in Tarc's existing courses.
See also: English Alphabet · English Listening & Speaking · Learn English