Reference thresholds for the ER-3A insert earphone

Area of Science:

• Audiology
• Acoustics
• Hearing Instrument Technology

Background:

• The ER-3A insert earphone is increasingly considered a substitute for the TDH-39/MX-41AR.
• Existing data requires analysis to establish reliable reference threshold levels for the ER-3A.

Purpose of the Study:

• To analyze data from multiple studies to estimate reference threshold levels for the ER-3A earphone.
• To compare these estimates with manufacturer specifications and established audiological standards.

Main Methods:

• Meta-analysis of data from five recent studies involving the ER-3A earphone.
• Conversion of sound pressure levels (SPLs) from a 2-cc coupler to Zwislocki-coupler-equivalent SPLs.
• Comparison of results with provisional reference threshold SPLs and revised minimum audible pressures.

Main Results:

• Mean data from the five studies align within 1 dB of the ER-3A manufacturer's provisional reference threshold SPLs (HA-1, 2-cc coupler).
• Converted SPLs show agreement within 1.5 dB with Killion's revised minimum audible pressures across audiometric frequencies.
• The ER-3A earphone demonstrates reliable performance comparable to established standards.

Conclusions:

• The ER-3A insert earphone can be used as a substitute for the TDH-39/MX-41AR without recalibration in most audiological applications.
• Both manufacturer's provisional SPLs and the study's averaged results provide accurate reference levels for the ER-3A.
• This analysis provides a validated basis for using the ER-3A in hearing assessments.