What is ritornello form?

Ritornello form is a musical structure commonly used in the Baroque period, particularly in concertos and other instrumental works. The key characteristic of ritornello form is the presence of a recurring theme, known as the "ritornello." This theme typically alternates with contrasting sections, which can feature different musical material. The repeated return of the ritornello provides a unifying element throughout the piece, allowing listeners to identify and anticipate its reappearance.

In contrast, other forms mentioned do not align with the definition of ritornello. A form that has no repeated sections would lack the core feature of a returning theme, while a form exclusively using solo instruments does not specifically define ritornello, as it can involve orchestral accompaniment. Additionally, while variations in dynamics may occur within a ritornello, they are not a defining feature of the form itself. Therefore, the correct understanding of ritornello form centers around its characteristic of featuring a recurring theme.