▁processing ▁the ▁sounds ▁of ▁language . ▁ ▁Some ▁research ers ▁have ▁studied ▁the ▁structure ▁and ▁function ▁of ▁neural ▁path ways ▁in ▁the ▁language ▁areas ▁of ▁the ▁brain . ▁O thers ▁have ▁focused ▁on ▁the ▁per ception ▁of ▁short ▁or ▁rapidly ▁varying ▁sounds ▁of ▁language , ▁pos iting ▁that ▁the ▁core ▁def ic it ▁is ▁one ▁of ▁timing ▁rather ▁than ▁of ▁overall ▁function . ▁ ▁In ▁the ▁past ▁two ▁dec ades , ▁the ▁ph on ological ▁def ic it ▁hypothesis ▁has ▁been ▁the ▁dominant ▁explanation ▁fav ored ▁by ▁research ers ▁as ▁to ▁the ▁probable ▁cause ▁of ▁d ys lex ia , ▁but ▁it ▁is ▁only ▁one ▁of ▁several ▁compet ing ▁theories . ▁Crit ics ▁of ▁the ▁ph on ological ▁hypothesis ▁point ▁out ▁that ▁it ▁fails ▁to ▁account ▁for ▁sympt oms ▁of ▁d ys lex ia ▁un related ▁to ▁ph on etic ▁dec oding ▁difficulties , ▁such ▁as ▁problems ▁with ▁short - term ▁memory , ▁visual ▁processing ▁issues , ▁or ▁difficulties ▁with ▁balance ▁and ▁small ▁motor ▁coord ination ▁that ▁are ▁common ▁to ▁many ▁d ys lex ic ▁children ▁and ▁adult s . ▁ ▁They ▁also ▁argue ▁that ▁much ▁of ▁the ▁evidence ▁for ▁the ▁theory ▁is ▁based ▁on ▁circular ▁reasoning , ▁in ▁that ▁ph on ological ▁weak ness ▁is ▁seen ▁as ▁both ▁a ▁defining ▁sympt om ▁of ▁d ys lex ia ▁and ▁as ▁its ▁underlying ▁cause . ▁ ▁See ▁also ▁ ▁Aud itory ▁processing ▁dis order ▁Ph on eme ▁Ph on em ic ▁aw aren ess ▁Ph on ics ▁Ph on ology ▁Pseud ow ord ▁Reading