The term applied to musical techniques employed in specific musical genres during specific musical eras. Quite often, performance practice refers to techniques that are implied, and not written or notated. Some examples would include the technique of using vibrato in some forms of jazz. Although not always notated, certain styles of jazz expect the use of vibrato. Ornamentation has changed throughout the years and the interpretation of most of the common ornaments need to be performed in the style appropriate to the era. the study of the way in which a piece would have been performed, including issues of timbre (voices or instruments and the quality of the sounds they make), ornamentation, size of ensemble, appropraite techniques and the like. The historical performance practice movement approaches a work by studying the conventions that guided its early performances. See historically informed. indicates the attempt to perform music in the way envisaged originally by the composer. the second half of the 20th century has brought a significant interest in musicology and the technology and scholarship necessary to the construction of copies of earlier instruments and to the study of methods of performance on these instruments. The study of performing practice extends from the study of music of the earliest periods to that of relatively recent periods of the 19th and early 20th centuries.