Airy, light, poetic, mellow, bright, wafting, ethereal, rich, soft, graceful, penetrating, brilliant, clear, shrill, silvery, wind-like, whistling, whispering, humming, filigree, sighing, aspirate.
The timbre of the concert flute is homogeneous in all registers with only the very lowest and highest notes exhibiting any different qualities.
B3 – B4
Because they contain few overtones, the lowest notes can sound rather dull, dry and hollow which gives them a melancholy character.
They are used mostly in solo pieces or in small, carefully-balanced ensembles to prevent them being drowned by other instruments. The overtones of the double-bass in particular superpose the lowest flute notes. It is for this reason that several flutes are used to boost the volume.
C5 – B5
In the middle register the flute sounds mellow, light, wafting, bright and rich. These characteristics are often used for solo work. In quiet passages the flute’s middle register sounds particularly graceful.
C6 – D7
The higher notes possess great brilliance and can sound penetrating and shrill.
They are ideally suited for playing melody lines along with the violins, and are therefore found fulfilling precisely this task in practically every orchestral work.
They are, of course, also used for solo performance.