Complex sentence: Acoustically, however, the important element is the place of the rearmost occlusion, the point that the resonant chamber in the mouth terminates, which determines the size and shape and so the acoustics of the oral cavity, which produces the harmonics of the vowels.
Split into simpler sentences: Acoustically, however, the important element is the place of the rearmost occlusion, which is the point that the resonant chamber in the mouth terminates. That determines the size, shape and acoustics of the oral cavity, which produces the harmonics of the vowels.