As in music, stress and accent in natural language are phenomenal prominences. A phenomenal prominence is always the most salient aspect of an acoustic contrast. A stress or accent might consist of a higher pitch, a greater amplitude, or a longer duration. It might also arise from differences in aspiration, vowel quality, or voicing. The primary purpose of stress and accent is to indicate a form’s temporal structure. It does this by indicating the positions of metrical prominences on the metrical grid. When phenomenal prominences correspond to metrical prominences, as they do in both music and language, they indicate the locations of metrical prominences and overall temporal organization. The key difference between metrical patterns in music and metrical patterns in language is that the former are typically more cyclic – or repetitive – than the latter with a more even distribution of prominences. Metrical organization is always rich and constructed automatically. Even when presented with a series of identical isochronous pulses, a hearer will automatically construct an analysis with multiple metrical levels. Stress and accent indicate which metrical analysis a listener should construct. This typically requires minimal information. A single accent per form can distinguish between the four perfect grid patterns, the simplest binary metrical patterns.