DD45 Headphones for Audiometer ( Original Radio Ear ) Dynamic Receiver 10 ohm Standards: ANSI S3.6-2010; IS0389-1 1998 Earphone Receiver: Dynamic moving coil, specially built for audiometry Nominal Impedance: 10 ohm Frequency Response: 100 Hz โ 8 kHz Linearity: Linear up to 500 mW Sensitivity: Typically 106.7 dB SPL re. 20 ยตPa output with 1 mW input, f=1 kHz Harmonic Distortion: Below 1% at 120 db SPL, f=kHz