Audio transcription is a hard problem that is inherently non-deterministic and probabilistic due to ambiguities in the speech due to: 1. accents -- Especially

Audio transcription is a hard problem that is inherently non-deterministic and probabilistic due to ambiguities in the speech due to: 1. accents -- Especially around mergers (cot-caught [AmE], trap-bath [BrE] vs palm-bath [LondonE], pin-pen [Some AmE]). These can even be hard for native speakers -- try transcribing a broad Scottish, London, Brooklyn, or Indian accent and see how well you do. 2. sound/phoneme variation based on surrounding phonemes -- It is common for the 'n' sound to be realised as an 'ng' sound before a 'k' or 'g' sound due to velarization ('ng' is the velar variant of 'n' and 'k' and 'g' are velar sounds). It is common for vowels to be nasalized before nasal sounds ('n', 'm', 'ng'). It is also common in non-rhotic (don't pronounce the 'r's next to vowels like in 'start' and 'north') to pronounce an 'r' between two adjacent vowels in words ending/beginning with vowels (the "intrusive r", e.g. in "there and back"). 3. sound changes due to fast speech ("I'm gonna see 'bout it t'day.", etc.) 4. ambiguity about where words start/end (e.g. "to Damon" vs "today mon" where the "mon" is the variant of "man" in Caribbean English). 5. word play, puns, etc. due to accent and other speech. 6. technical words in a given domain, specific place names, etc. 7. other things that can affect speech such as mumbling, stuttering, or slurred speech.