00307nam a22000737a 4500245014900000260005800149300000900207650001700216  aIS 10781:1984-Specification for Reference Coupler for the Measurement of Hearing Aids Using Earphones Coupled to The Ear by Means of Ear Inserts  aNew Delhi :bBureau of Indian Standards (BIS),c1984.  a7 p.  aHearing aids