Mouthpiece structure
There is a direct relationship between the physical characteristics of a mouthpiece (tip opening, table and baffle) and its musical and acoustic characteristics (tone, roundness, volume, intonation and ease of playing).
Even the slightest variations in the dimensions of the different parts of a mouthpiece can lead to significant differences in the resulting sound!
The baffle, for example, acts as a reflector for the reed. The higher it is (closer to the reed), the more bright the sound; conversely, the lower the baffle, the rounder the sound.
Generally speaking, the more the reed is constrained, the rounder the sound.
The window allows the reed to vibrate. A shorter window produces a rounder sound and greater resistance at the attack.
Similarly, the thicker the rail, the rounder the sound.