Note OffEdit
Note Off is a foundational concept in music technology describing the moment a previously sounding note ends. In both hardware keyboards and software instruments, this event signals the release of a key or the cessation of a control signal, allowing the sound to stop or to enter its release phase. In digital systems such as MIDI, the Note Off event serves as a formal instruction to terminate a voice, though practical implementations vary across devices. Some systems use Note On messages with zero velocity as a stand-in for Note Off, which is a widely adopted workaround in the industry. The handling of note-off events directly affects articulation, timing, and the overall feel of a performance, especially in polyphonic contexts where multiple voices run simultaneously.
Technical background
Note On and Note Off
In most conventional systems, a Note On event starts a voice, while a Note Off event ends that voice. The distinction between the two is central to how sound is generated and released. The envelope generator that shapes a voice—with stages such as attack, decay, sustain, and release (ADSR)—often enters its release phase when a Note Off is received. This release phase determines how long the note rings after the key is released or after the triggering control signal ends. For discussions of the related mechanism, see envelope generator and VCA (voltage-controlled amplifier).
MIDI representation
Within the MIDI framework, notes are represented by discrete messages on a given channel. A Note Off message explicitly indicates termination of a previously triggered note, while a Note On message begins a new note. In practice, many devices implement Note Off as a dedicated message, with a status byte indicating Note Off and a data pair for the note number and release velocity. An alternative approach used by a substantial subset of equipment is to treat a Note On with a nonzero note velocity as the start of a note and a Note On with velocity zero (or a Note Off message) as the release. This duality—Note On/Off versus Note On with velocity zero—has implications for sequencing and compatibility across devices. See MIDI for the protocol details and Note On for the related concept.
Release phase and envelope control
The release phase defines how a voice winds down after a Note Off is issued. The release time, governed by the envelope generator, determines whether a note stops abruptly or fades out smoothly. In performance, shorter release times can produce crisp, staccato phrasing, while longer releases contribute to legato and sustain, even when the performer lifts the key promptly. The interaction between note-off events and the sustain mechanism, such as a sustain pedal, shapes the final auditory result. See envelope generator for more on how ADSR parameters influence the release behavior.
Hardware and software implementations
In hardware synthesizers, a gate or trigger signal may replace MIDI Note On/Off in controlling voice allocation. In software environments, digital audio workstations or plugin instruments interpret incoming note-off events to terminate voices or to transition them into release states. In polyphonic setups, multiple instances of a voice may be active, requiring careful voice allocation and sometimes “note stealing” to free resources when new notes are triggered while others are still releasing. See polyphony and voice allocation for related concepts.
Articulation and performance implications
Note-off timing is central to articulation. Short, clean note-offs yield precise staccato effects, while delayed release can blur notes together for legato phrasing. The design of a sound library or a instrument’s default release behavior can influence playing style and expressive possibilities. In a performance or sequencing context, the timing of note-off events interacts with rhythmic interpretation and the envelope’s release tail, affecting perceived tempo and groove. The same principle applies in sample-based playback, where a note-off may also terminate a sample or trigger a release sample, depending on the instrument’s design. See sampler and sample for related discussions.
Practical considerations in playback and sequencing
In live performance setups, reliable handling of note-off events is essential for predictable timing, especially when multiple controllers or MIDI channels are in use. This reliability rests on consistent interpretation of Note Off versus Note On with velocity zero across devices. See MIDI for protocol variations.
In sequencing and piano-roll editing, events are typically encoded as Note On and Note Off pairs. Accurate representation of these events ensures precise articulation and proper alignment with the project’s tempo and groove. See piano roll for a common visualization of note events.
Release behavior interacts with the sustain mechanism and with any built-in or external effects. Long release tails can influence tail-processing in reverbs and delays, altering the final spatial impression of a recorded performance. See reverb and delay for related effects.
Controversies and debates
The MIDI standard and its treatment of note-off events have evolved through industry discussion and practical necessities. Some engineers and producers favor the strict use of Note Off messages to terminate voices, arguing that explicit signaling yields more predictable behavior across hardware and software. Others rely on Note On with velocity zero due to historic compatibility and simplicity in older equipment. This divergence has implications for compatibility in live rigs, studio setups, and educational materials. In practice, both approaches coexist, and understanding the target gear is important for interoperability. There is no broad, consensus-driven political controversy around this technical choice, but industry preferences can influence workflows, product design, and retrofitting of older systems.