Interface defect response time is a key parameter in MOS devices interface defect density measurements such as the hi-lo CV measurement as well as the conductance measurement. It is widely accepted that interface defects at energies close to the band edge have too short a response time to be measured properly by these techniques, unless very high measurement frequencies are employed, which is challenging experimentally. Consequently, near band edge interface defects are difficult to measure. Here we show that the time constant of band edge defects are not as short as commonly believed. Specifically, we show that as the capacitor is biased into accumulation to measure defect levels near the band edge, the defect response time levels off instead of continue to decrease. As a result, the commonly available 1MHz measurement frequency is more than adequate even for defects near the band edge.