 Notes can be a single note , or composed of two to five notes that make a chord . Both single notes and chords can also be sustained , indicated by a colored line following the note marker ; the player can hold the sustained note ( s ) keys down for the entire length for additional points . During a sustained note , a player may use the whammy bar on the guitar to alter the tone of the note . Also , regardless of whether <unk> are hit early or late , if the fret is held for the full duration of the hold , the game will always award the same amount of score increase for the note . In addition , the games support virtual <unk> of " hammer @-@ <unk> " and " pull @-@ offs " , guitar @-@ playing techniques that are used to successfully play a fast series of notes by only changing the fingering on the fret buttons without having to strum each note . <unk> where strumming is not required are indicated on @-@ screen by notes with a white outline at the top of the marker instead of the usual black one , with Guitar Hero III : Legends of Rock adding a white @-@ glowing effect to make these notes clearer . Guitar Hero World Tour features transparent notes that are connected by a purple outline ; players may either simply tap the correct fret for these notes without strumming or utilize a <unk> on World Tour 's guitar controller to mimic the slide technique . In addition , notes can now be played while a sustained note is being played . World Tour also adds an open string note for bass players , represented by a line across the fret instead of any note gems , that is played by strumming without holding down any fret buttons ( the sixth installment , Warriors of Rock , features an open note sustain for bass instruments as well ) . 
