In music, the term tessitura (Italian for "texture") generally describes the most musically acceptable and comfortable range for a given singer or, less frequently, musical instrument; the range in which a given type of voice presents its best-sounding texture or timbre. This broad definition is often interpreted to refer specifically to the pitch range that most frequently occurs within a given piece, or part, of music. For example, throughout the entirety of Wagner's Ring, the music written for the role of Siegfried ranges from C♯3 to C5, but the tessitura is described as high because the phrases are most often in the range of C4 to A4.
In musical notation, tessitura is used to refer to the compass in which a piece of music lies—whether high or low, etc.—for a particular vocal (or less often instrumental) part. The tessitura of a piece is not decided by the extremes of its range, but rather by which part of the range is most used. The tessitura of a part will often influence which clef a particular piece of music is written in.Melodic contour may also be considered to be an important aspect of vocal tessitura.
The "tessitura" concept addresses not merely a range of pitches but also the arrangement of those pitches. Tessitura considerations include these factors: proportion of sudden or gradual rises and falls in pitch—speed of pitch changes; the relative number of very high or low notes; whether lines and phrases of music in the piece tend to rise or fall—the muscular abilities of a singer may be more suited to one or the other direction.
Although frequently ignored in discourses on tessitura, the volume (loudness) which a singer is able to maintain for dramatic effect will often influence which "fach" (voice type) or tessitura he or she specialises in. For example a lyric tenor may have the vocal range to sing Wagner or other dramatic roles, but to maintain the loudness required for dramatic intensity over the span of an opera performance could either inflict vocal damage or be simply beyond the innate ability. Verdi's Otello is a good example of the need for a voice capable of substantial power throughout the length of a performance of the opera.