Isochrony is the idea that a leid rhythmically divides time intae equal portions. Three types o diveesions are postulatit:
- the temporal duration atween twa stressed seellables is equal (stress-timed);
- The duration o ivery seellable is equal (seellable-timed);
- the duration o ivery mora is equal (mora-timed).
The idea wis first expressed bi Ken Pike in 1945. While mony linguists find the idea o different rhythm types appealin, empirical studies hae no been able tae fynd acoustic correlates o the postulatit types, cawin intae question the validity o these types.