Intervala or Intervalla: How To spell?
The word Intervala is misspelled against Intervalla, which is plural of "Intervallum"
Intervalla has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings interva & a which should not be misspelled with single 'L'
Wrong Spelling:  interva-l-a  Correct Spelling:  interva-ll-a 
Explore spell check of Intervalla to spell without errors.