The Acoustic Test Environment for Hearing Testing

Audiology clinics traditionally employ expensive, prefabricated sound rooms to create an environment that is sufficiently quiet for accurate hearing tests. There is seldom any analysis of the need for or benefit from such enclosures. There may be less expensive methods that would decrease the cost of and increase access to hearing testing.

This report provides information concerning the need for and effectiveness of sound rooms and an analysis of the audiometric test ranges for various earphone/room combinations.

Acoustic measurements made in four rooms were analyzed with the attenuation provided by various earphone designs to determine the maximum permissible ambient noise levels and the corresponding audiometric test ranges.

The measurements and calculations were performed with four test rooms and five earphone designs.

Ambient noise levels and earphone attenuation characteristics were used to calculate the noise levels that reach the ear. Those were compared to the maximum permissible ambient noise levels that are provided in ANSI S3.1-1999 or calculated from measured attenuation levels. These measurements were used to calculate testable ranges for each room/earphone combination.

The various room/earphone combinations resulted in minimum test levels that ranged from -10 to 20 dB HL at various test frequencies.

When the actual benefits of expensive prefabricated sound rooms are assessed based on the range of hearing levels that can be tested, the effectiveness of that approach becomes highly questionable. Less expensive methods based on planning the clinic space, use of inexpensive sound treatments, and selecting an appropriate earphone can be effective in almost any space that would be used for hearing testing.