The double layered ear-shells are engineered to reduce resonance and vibration, bringing you genuine sound and uncompromised detail and the specially tuned diaphragm maintains uniform sound precision. The memory foam earpads are covered with a highly breathable velour material, keeping your ears cool and comfortable. The frequency range covered by the Philips Fidelio X1 headband headphones is 10 Hz - 40 kHz. With 30 ohms impedance level it has a 100 dB sensitivity.