Are Sound Booths Necessary?
Margolis and Madsen (2015) examined the need for (or lack of) and effectiveness of sound rooms/booths. They considered the testing ranges of people undergoing audiometric tests, as well as an analysis of four different test rooms/booths and five different earphones. The multiple test results (combinations of booths and earphones allowed testing from -10 to +20 dB HL) allowed accurate testing across the test frequencies employed in clinical audiology.
Maclennan-Smith (2013) demonstrated that while using circumaural headphones and inserts (Etymotic ER3A) in a quiet room, they obtained air and bone thresholds that had “no significant differences” from sound rooms.
Margolis and Madsen report that test environment and selection of earphones is inextricably linked to the lowest level at which we desire to obtain thresholds. That is, one must consider that our focus is on people with hearing impairment—and their thresholds are generally above 25 dB HL. As such, perhaps it is less important to concentrate on the ability to test -10 dB to +20 dB (in every single test environment) as those same results are likely to be considered “normal.”
The results of their analysis (figure three, page 6 of their publication) indicate that for the test rooms and transducers evaluated “there is no significant advantage of two-room, double-wall sound suite over a single prefabricated single-wall room.” Further, give the worse-case scenario (TDH-50 headphones in two of the less well performing booths) “all patients with communicatively significant hearing losses would be tested accurately….”
For More Information, References, and Recommendations
Margolis RH, Madsen B. (2015) TUTORIAL—The Acoustic Test Environment for Hearing Testing. Journal of the American Academy of Audiology 26:1–8.