Effects of background noise on earphone thresholds

Area of Science:

• Audiology
• Hearing Science
• Acoustics

Background:

• Accurate hearing threshold measurement is crucial for diagnosing hearing loss.
• Background noise levels can significantly impact the reliability of audiometric testing.
• Different earphone types offer varying degrees of sound isolation.

Purpose of the Study:

• To compare the real-ear attenuation at threshold (REAT) of supra-aural, Audiocup, and insert earphones.
• To evaluate the impact of background noise on pure-tone thresholds using different earphones.
• To determine the lowest hearing levels measurable under specified ambient noise conditions.

Main Methods:

• Real-ear attenuation at threshold (REAT) and monaural pure-tone thresholds were measured in normally hearing adults.
• Testing was conducted in quiet and in background noise approximating ANSI S3.1-1991 and OSHA (1983) maximum permissible ambient noise levels (MPANLs).
• Three earphone types were used: supra-aural, Audiocup, and insert earphones.

Main Results:

• Insert earphones demonstrated the highest REAT, followed by Audiocup, then supra-aural earphones.
• Mean threshold shifts were minimal for all earphones in ANSI noise and for insert earphones in OSHA noise.
• Accurate thresholds down to 0 dB HL were achievable with insert earphones in both noise conditions, and with all earphones in ANSI noise.

Conclusions:

• Insert earphones are recommended for audiometric testing in environments with high ambient noise levels.
• Supra-aural and Audiocup earphones may not be suitable for testing down to 0 dB HL in OSHA-defined noisy environments due to insufficient REAT.
• Standardized noise levels and appropriate earphone selection are critical for reliable hearing threshold assessment.