Accent is not really related to tone although some speakers use a different tone during the accent.
It is actually related to timing. We tend to pace ourselves based on these accents so that for instance you may be speaking at a rate of one accent per second meaning you will naturally shorten syllables which are outside of the accent.
It is far easier to notice on longer words. In this sentence it doea almost sound ambiguous as to which syllable he did accent, but i had to listen hard to realize that as he is accenting it correctly enough for the word to sound normal to me.
A syllable-timed language is a language whose syllables take approximately equal amounts of time to pronounce. It can be compared with a stress-timed language, where there is approximately the same amount of time between stressed syllables. Learners whose first language can be described as syllable-timed often have problems recognising and then producing features of English such as contractions, main and secondary stress, and elision.
In a syllable-timed language, every syllable is perceived as taking up roughly the same amount of time, though the absolute length of time depends on the prosody. Syllable-timed languages tend to give syllables approximately equal prominence and generally lack reduced vowels.