If 30 must obtain for the given parameters, try rather:

=INDEX($I$7:$N$13,MATCH(C3,$G$7:$G$13,1)+(LOOKUP(C3,$G$7:$G$13) < C3),MATCH(C4,$I$6:$N$6,1))

which will also produce a correct value when Reference Dia. dB = 26.