How fast can we speak, and why?
The speed at which we are able to speak and be understood falls within quite a tight range, even across different languages, with typical values of:
English: 6 syllables per second
Mandarin: 5 syllables per second
Spanish: 8 syllables per second
This corresponds, in round numbers, to about 100 ms (thousandths of a second) per syllable, around 300 ms per word and around 200 words per minute.
This closely relates to the timing of a single cognitive cycle (the basic timeslot over which the mechanisms of consciousness repeat), which is also around 300 ms. This is made up of 3 steps:
0-100 ms perception
100-200 ms understanding
200-300 ms action selection.
My interpretation of this is that the syllable is the smallest unit that we are able to separately perceive and recognise, or produce when speaking, as a distinct entity, while a word is the fundamental unit of conscious understanding.
Across different situations we do cope with different rates of speech or reading, albeit with some variation in the amount of information conveyed and the level of understanding we achieve:
Silent reading speed: 250-300 wpm (words per minute)
Slow college graduate reader: 300 wpm
Fast college graduate reader: 600 wpm
Skim reading: 700+ wpm
Presentations: 100 wpm
Audio books: 150-160 wpm
Auctioneers: 250 wpm
Fastest debaters: 350-500 wpm
Nevertheless it is the overall similarity of these rates that is more striking than their differences.
Higher levels of language structure (parts of speech, building up to phrases or sentences) correspond closely to the mechanisms of consciousness, as described in my ebook 'On the mechanisms of consciousness' (available on Amazon for only £3 - do take a look!). For example we think in terms of distinct objects, named using words, and charactise them with respect to their attributes, such as colour, which correspond to adjectives.