Mepụta ụdị nkebi ahịrịokwu a dị mgbagwoju anya Ihe ngosi ultrasound na - enyere ndị na - eri anụ abalị aka ịmụta izere ụkpara Dunning DC, Roeder KD ( 1965 ) Ụkpara na - eme mkpọtụ na àgwà ụmụ ahụhụ na - ejide ụkpara.
N'ezie, ụdị ahịrịokwu dị mgbagwoju anya bụ "Mgbaàmà ultrasound na-enyere ndị na-eri anụ abalị aka ịmụta izere ikpuru (Dunning na Roeder 1965, Hristov na Conner, 2005), ma nwee ike igbochi ikike bat nwere iji chọpụta kpọmkwem ikpuru na-efe efe (Ratcliffe na Fullard, 2005). "