Western musical notation uses a stave — also known as a staff — consisting of five lines and four spaces upon which musical pitches can be notated. The interpretation of these pitch notations depends on which clef is associated with the stave. The treble clef indicates that the lowest line of the stave is to be interpreted as the note E above middle C. The bass clef is used to notate lower pitches; in bass clef the top line of the stave represents the A below middle C.
The pitches the flute is able to play lie mainly within and above the compass of the treble clef. A flute's lowest note is middle C, which is written one leger line below the treble clef's lowest line. The flute has a range of three octaves, making its highest note a C written above the fifth leger line at the top of the treble clef. When writing for the higher range of the flute, composers may write the notes an octave lower so that they are closer to the stave in treble clef. In this case the symbol "8va" would be used to tell the flautist to play the notes an octave higher than they are written.
Music for the trumpet is written in the treble clef, as the notes a trumpet can play typically lie comfortably within the range of the treble clef. The trumpet has a normal range from the F# below middle C to the C above the treble clef. Experienced trumpet players may be able to extend the range another fifth or so above this top note. The trumpet is a transposing instrument, as it is typically manufactured in the key of Bb. This means that when a trumpeter plays a scale of C major on her instrument, the pitches produced are actually those of the Bb scale. Each note written for the trumpet on the treble clef will actually sound one whole step lower than the written pitch.
The violin is the highest pitched string instrument typically found in the Western orchestra. Violin music is written in treble clef as this is the most suitable clef for the violin's high range. The lowest note on a violin is the G below middle C, which is notated below the second leger line under the treble clef. The highest violin note is the G four octaves above middle C. As with the flute, violin music in the higher register of the instrument may be made more readable through notation an octave lower, using the "8va" symbol.