Resurrecting a very old thread here, but I was researching this topic and have some new information.
It was said, "the lips vibrate/buzz to produce the sound, so how do the robots make sound?" There is a fundamental property of physics that must be understood to know
HOW the lips vibrate. When a trumpet player plays a note, they
DO NOT make their lips buzz. Their lips vibrate in sympathy with the motion of the air. Meaning that when air is passed through the lips and into the trumpet, a standing wave is created within the instrument, and the lips vibrate in sympathy with the motion of the air. In a standing wave, there are two points of maximum compression/tension created, and these are called nodes. The wave moves between these two point, and depending upon the length of that wave, you will get higher and lower notes. As the wave/air bounces back to the lip, they vibrate and make tone.
Now, a trumpet players lips vibrate faster or at a greater rate when the pitch is higher. This is actually a result of the air moving faster to create the higher tones. There is also an aperture in the lips through which the air moves, and this changes size in relation to the pitch and speed of the air. Basic take away, lower notes, slower air. Faster notes, faster air. Lower notes, a slower rate of sympathetic vibration in the lip and a more open aperture. Higher notes, a faster rate of sympathetic vibration and a smaller aperture.
The way this robot works; a synthetic mouth is created. Most likely using latex and a basic "dental structure." The mouthpiece is placed on these "lips," and internal air compressor moves air through the lips and into the trumpet and tones are produced. One of the most important things to remember is that the trumpet is a static instrument, it cannot produce sound with out air and sympathetic vibrations from the lips. If you were to take the instrument away from the robot's "mouth" and allow the air to continue moving through the robot's "lips," you'd simply hear a hissing sound. Again, the vibration is created in conjunction with the motion of the air and the standing wave within the instrument.
So, basically the robot "blows" air through the trumpet the same way a trumpet player does. The difference is there is no muscle structure or creative process in the "mind" of the robot, and therefore it cannot manipulate it's sound to produce anything beyond a very basic tone. I hope this helps those of you curious about the trumpet robot, and I'd love to know if there are more questions! If we really want to go down the rabbit hole, we can talk about the uproar this little guy created within the trumpet pedagogy community at the time of his release
