In noisy environments the oscillator can be crucially affected. If the noise is strong enough, the oscillator can “lock up” and stop oscillating. To reduce the sensitivity of the oscillator to noise, the size of the capacitor at the high-impedance input of the oscillator circuit, XTAL1, can be slightly increased. Increasing only one of the capacitors does not affect the total capacitive load much, but unbalanced capacitors can affect the resonant frequency to a higher degree than the change of the total capacitive load. However, unbalanced capacitive loads will affect the duty cycle of the oscillation and should not be used. This is especially critical if the AVR device is utilized close to its maximum speed limit.