information:classification, linguistic:voice_change
Construction

Accordions have many configurations and types. What may be easy to do with one type of accordion could be technically challenging or impossible with another, and proficiency with one layout may not translate to another.

The most obvious difference between accordions is their right-hand sides. Piano accordions use a piano-style musical keyboard; button accordions use a buttonboard. Button accordions are furthermore differentiated by their usage of a chromatic or diatonic buttonboard for the right-hand side.

Accordions may be either bisonoric, producing different pitches depending on the direction of bellows movement, or unisonoric, producing the same pitch in both directions. Piano accordions are unisonoric. Chromatic button accordions also tend to be unisonoric, while diatonic button accordions tend to be bisonoric, though notable exceptions exist.

Accordion size is not standardized, and may vary significantly from model to model. Accordions vary not only in their dimensions and weight, but also in number of buttons or keys present in the right- and left-hand keyboards. For example, piano accordions may have as few as 8 bass buttons (two rows of four), or up to 140 (seven rows of twenty) or beyond. Accordions also vary by their available registers and by their specific tuning and voicing.

Despite these differences, all accordions share a number of common components.