Survey examines popularity of real-ear probe-microphone measures

It was in 1979, at the International Ear Clinics’ Symposium, that Earl Harford, PhD, first described a new technique to assess the performance of hearing aids by putting a microphone in the ear canal so that actual realear gain and output could be measured. Many believed that the “science” component of fitting hearing aids had finally arrived. By the mid-1980s, leading audiologists were predicting that real-ear probe-microphone measures would be used by nearly everyone by the end of the decade. But that didn’t happen. In fact, it didn’t happen in the ‘90s or in the ‘00s either, despite Best Practice Guidelines, such as those of the American Academy of Audiology (AAA), stating: “Prescribed gain (output) from a validated prescriptive method should be verified using a probe-microphone approach that is referenced to ear canal SPL.” That’s a pretty unambiguous statement. Here at HJ, we’ve periodically sampled the use of real-ear probe-mic measures through dispenser surveys. For example, in 1995 we found that “routine” use of these measures was reported by 54% of audiologists (n=134) and 18% of hearing instrument specialists (HISs; n=108), with an overall use rate of 39%. In 1999, we examined use rates for both groups, but limited it to those who owned or had access to the equipment. Even then, only 42% reported routine use. Our 2003 survey showed an overall use rate of 37% (n=558 audiologists, 49 HISs). And finally, in a 2005 survey, we again examined the popularity of these measures, this time just among audiologists. The overall use rate was 34%. It was slightly higher (~40%) for recent graduates (either masters or AuDs) and for experienced audiologists who had obtained their AuD through distance learning. For some reason, or probably for many related reasons, using real-ear probe-mic measures for verification of hearing aid performance has never become the prevailing practice. Our past surveys suggest that only about 1/3 of dispensers have been using this verification approach routinely, with no meaningful upward trend observed.