Pitch is determined by tube dimensions, material it is made from, tension on the reed(s), and pressure of lip on the reed which regulates air pressure and velocity. What you can control is reed tension. In general, the more tension on the latex, this higher pitch the tube will produce. It can be too loose which makes it difficult to control. Also less lip pressure with softer air will lower the tone.
Many a real hen start with a whine. Good luck. I started getting serious with tubes a few months back and am having a blast with them.