Vibrato is a musical effect produced by incorporating a pulsating change in pitch, which adds expression to singing and instrumental music. It is characterized by the amount of pitch variation and the speed at which the pitch is varied. Tremolo is a quivering effect caused by rapid repetition of a single tone's volume. Portamento is a smooth glide between tones, especially in voice or bowed strings. MIDI is a standardized digital language that allows electronic instruments and computers to communicate, translating performance data into messages that can control sound production and recording in a connected network.