The sixth age shifts Into the lean and slippered pantaloon,
With spectacles on nose and pouch on side, His youthful hose, well saved, a world too wide
For his shrunk shank; and his big manly voice,
Turning again toward childish treble, pipes And whistles in his sound.
(a) Which is the stage of man's life that the poet describes here?
(b) Give the meaning of 'shrunk shank'.
(c) Why does his voice again turn ‘toward childish treble'?