cept ual ▁evaluation , ▁which ▁includes ▁ac oust ic ▁and ▁aer od ynamic ▁measures , ▁alone ▁is ▁ins u fficient . ▁L ary n ge al ▁vide ost rob os copy , ▁an ▁imag ing ▁technique , ▁is ▁commonly ▁used ▁to ▁view ▁the ▁vocal ▁fol ds : ▁this ▁procedure ▁can ▁be ▁performed ▁nas ally ▁or ▁or ally . ▁V ocal ▁fol d ▁nod ules ▁are ▁most ▁often ▁character ized ▁as ▁bil ater ally ▁symmet rical ▁wh it ish ▁masses , ▁and ▁tend ▁to ▁form ▁at ▁the ▁mid point ▁of ▁the ▁vocal ▁fol ds . ▁ ▁N od ules ▁may ▁prevent ▁complete ▁closure ▁of ▁the ▁gl ott is , ▁also ▁known ▁as ▁gl ott al ▁closure , ▁and ▁their ▁presence ▁may ▁lead ▁to ▁an ▁hour glass - sh aped ▁gl ott al ▁closure . ▁Vo ice ▁problems ▁may ▁result ▁from ▁the ▁presence ▁of ▁vocal ▁fol d ▁nod ules . ▁ ▁They ▁are ▁diagn osed ▁based ▁on ▁the ▁presence ▁of ▁per cept ual ▁features ▁not ▁explic able ▁by ▁other ▁causes . ▁Such ▁sympt oms ▁include : ▁vocal ▁fat igue , ▁breath iness , ▁loss ▁of ▁high ▁pitch ▁notes , ▁lack ▁of ▁vocal ▁control , ▁or ▁increased ▁ph on atory ▁effort ▁( i . e . ▁increased ▁effort ▁to ▁produce ▁speech ). ▁ ▁Pre vention ▁ ▁Reg ulating ▁voice ▁use ▁ ▁For ▁individuals ▁who ▁work ▁with ▁their ▁voice ▁( e . g ., ▁sing ers , ▁actors , ▁teachers , ▁stock ▁bro k ers ) ▁voice ▁training ▁that ▁includes ▁vocal ▁function ▁exer cis es ▁( VF