Attenuation provided by audiometric earphones

Abstract

The attenuation provided by TDH-49 earphones in P/N 51 cushions and ER-3A insert earphones using modified foam earplugs was determined for 24 subjects using a real-ear attenuation at threshold paradigm (ANSI S3.12-1984). The TDH-49 earphones were fitted on each subject as normally done for audiometry and the ER-3A earplugs were inserted into each subject's ear canals so that the outer edge was flush with the floor of the concha. Compared with the TDH-49, the ER-3A provided about 18 dB more attenuation for the lower (125–500 Hz) and about 15 dB more attenuation for the higher (1000–8000 Hz) frequencies. Implications concerning the use of TDH-type earphones and ER-3A insert earphones in reference to permissible ambient noise levels for audiometry (ANSI S3.1-1977) will be discussed.