Part 3/11:
He demonstrates that the flutes and piccolos are playing octave B flats—one octave apart—creating a layered, shimmering effect. The oboes and clarinets, both in the B flat family, reinforce the chord with their own octave B flats, but with unique transposing considerations. For instance, clarinets are B flat instruments, sounding a whole step lower than written, so the composer writes their parts a whole step above what should sound.
The bass clarinet, which sounds a ninth below written pitch, adds depth by covering another octave range of B flats, making the chord richer and more sonorous. When all these woodwind parts are played simultaneously, they form a cluster of rooted B flats, emphasizing the fundamental tone of the chord.