Abstract:
Investigating the appropriate experimental conditions and parameter settings for evaluating active noise-cancelling earphones’ performance is crucial for developing industry standards and conducting enterprise product tests. This study utilizes three types of active noise-cancelling earphones to explore the effects of sound source layout and quantity on noise reduction measurements. In an anechoic chamber, various numbers of sound sources are positioned at different azimuthal angles to measure earphones’ noise reduction capabilities. The study analyzes the earphones’ active noise reduction performance under varying sound source conditions. Results indicate that in the earphones’ primary operational frequency band, using a single sound source placed at different angles and averaging these measurements can substitute for testing with eight simultaneous sources. The mean of two measurements with four sources at corresponding angles closely aligns with the European Telecommunications Standards Institute’s current eight-source testing standard. Thus, for active noise reduction assessment, using a single sound source at multiple angles for separate noise reduction measurements, and averaging these results, can effectively replace the need for eight simultaneous sources. A more precise approach involves two measurements with four sources at designated angles, with the results averaged. These methodologies simplify the testing apparatus while ensuring measurement reliability.