The place theory suggests that sounds with different pitch generate neural messages in different sets of neurons, which in turn induce different fibers in the hearing cortex. The place theory of pitch perception states that different portions of the basilar membrane are sensitive to sounds of different frequencies. So this theory cannot completely explain how we perceive low pitch sounds that create synchronized reaction in the basilar membrane. According to the temporal theory, the activity level of a sensory neuron codes the frequency. This means that a given hair cell fires action potentials related to the frequency of the sound wave.