▁ ▁and ▁ ▁become ▁ ▁and ▁ ▁respectively , ▁if : ▁ ▁The ▁v owel ▁in ▁the ▁next ▁sy ll able ▁is ▁short ▁( th us ▁including ▁also ▁), ▁and ▁ ▁The ▁following ▁con son ant ▁is ▁quantity ▁ 1 ▁or ▁ 2 . ▁The ▁di ph th ongs ▁ ▁and ▁ ▁are ▁una ffect ed . ▁The ▁reverse ▁process ▁also ▁occurs , ▁turning ▁the ▁long ▁v ow els ▁back ▁into ▁di ph th ongs ▁if ▁the ▁con son ant ▁becomes ▁quantity ▁ 3 ▁or ▁the ▁v owel ▁in ▁the ▁next ▁sy ll able ▁becomes ▁long . ▁ ▁The ▁third ▁type ▁of ▁um la ut , ▁progress ive ▁um la ut , ▁works ▁in ▁the ▁other ▁direction . ▁It ▁causes ▁the ▁un str essed ▁v ow els ▁ ▁and ▁ ▁to ▁be ▁rounded ▁to ▁ ▁and ▁ ▁respectively , ▁if ▁the ▁preceding ▁str essed ▁v owel ▁is ▁short ▁. ▁ ▁Un str essed ▁v owel ▁length ening ▁ ▁If ▁a ▁str essed ▁sy ll able ▁contains ▁a ▁short ▁v owel ▁followed ▁by ▁a ▁single ▁( quantity ▁ 1 ) ▁con son ant , ▁then ▁a ▁short ▁v owel ▁in ▁the ▁following ▁sy ll able ▁is ▁length ened . ▁▁ ▁" to ▁do " ▁~ ▁dag á ▁( 1 st ▁p . ▁s g . ▁present ) ▁▁ ▁" to ▁tw ist " ▁~ ▁b ån j å ̄ ▁( 1 st ▁p . ▁s g . ▁present ) ▁ ▁Dia lect s ▁ ▁Sam mal la ht i ▁div ides ▁L ule ▁S