13. Extended techniques provide composers with more possible

+timbres
+rhythms
+textures
+ensembles

Timbres.

Explanation:

Extended technique is  non-conventional  methods in music produced through act  of singing or playing musical instruments to generate  unusual sounds  or improve the aural quality of a sound, known as Timbres.  Extended technique can vary from performer to performer and depends on choice or style of such performer.

c, d, e, f, g, a, b, and c.

sometimes western music will also use solfege. the names of these are do ra me fa sol la si (or ti) and do.

to indicate a note a half step higher or lower then the original note, you would say c # (for a half a step above c) or bb (for half a step below b)