velocitysensitive

Velocity-sensitive is a term used to describe instruments, controllers, and sensors that detect the velocity of a pressed surface and translate that information into a modulated output, such as louder sound, brighter timbre, or adjusted control signals. In musical electronics, velocity refers to how quickly or forcefully a key, pad, or surface is struck, not how long it is held.

In practice, a velocity-sensitive keyboard or pad measures press velocity and maps it to a velocity value (commonly 0–127 in MIDI). This value can then influence various sound parameters, most often volume, but also envelope timing, filter cutoff, or other aspects of a sound. Different devices implement velocity sensing with mechanical, optical, or capacitive methods, and may apply different velocity curves (linear, exponential, or user-adjustable) to shape the response.

Velocity sensitivity enhances musical expression by making stronger strikes produce louder or more vibrant sounds, while softer touches yield quieter or more subdued results. This is a core feature of many digital pianos, synthesizers, and drum controllers. By contrast, non-velocity-sensitive devices produce a fixed output regardless of how hard or soft they are played.

Some velocity-sensitive devices also support additional expressive channels, such as aftertouch, where pressure after the initial strike further modulates the sound. In MIDI terminology, velocity describes the initial touch, while aftertouch conveys ongoing pressure.