Dawes, Powell, and Munro (2011) investigated the impact of patient expectations with regard to hearing aid fittings. They reported 20 experienced hearing aid wearers (13 males, 7 females, aged 54 to 80) to evaluated “new” versus “conventional” hearing aid technologies. Of note, the two hearing aids were the same instrument housed in different colored shells, fitted and verified to the same National Acoustics Lab (NAL) prescription. Dawes, Powell, and Munro reported each participant was fitted with both devices (new and conventional) and measures included speech-in-noise tests, sound quality ratings, and personal preference. Fifteen of the 20 subjects preferred the “new” hearing aid, five could not tell any differences, and none preferred the “conventional” fitting.
Hopkins (2012) investigated the “reliability of the influence of participant expectation on the outcome of a trial that compared to identical hearing aids….” In this case, one hearing aid was described as “conventional” and the other was described as “new.” Sixteen adult hearing aid users participated. The protocol used was the same protocol used by Dawes, Powell, and Munro (see above). Hopkins reported that overall, 75 percent of the participants expressed an overall preference for the “new” hearing aid. Hopkins concluded “Placebo effects reliably impact hearing aid trials.”
For More Information, References, and Recommendations
Dawes P, Powell S, Munro KJ. (2011) The Placebo Effect and the Influence of Participant Expectation on Hearing Aid Trials. Ear & Hearing 32(6):767-774.
Hopkins R. (2012) Reliability of Placebo Effects In Hearing Aid Trials. British Academy of Audiology (BAA) Poster #24, Manchester, England.