Frequency Theory is a concept in psychology that suggests our perception of sound pitch is determined by the frequency of sound waves. According to this theory, the brain interprets the frequency of vibrations in the air, with higher frequencies corresponding to higher pitches and lower frequencies to lower pitches. This theory is particularly relevant in understanding how we hear and process sounds, especially in relation to musical notes and speech. It contrasts with the Place Theory, which posits that different pitches are perceived based on the location of stimulation along the cochlea in the inner ear.