Why do I feel tightness in my throat when I raise my pitch?

Sometimes people have tension in their Larynx prior to starting Voice modification, sometimes tension in the Larynx muscles happens when a person tries to use their voice differently.

Before you start doing the exercises, open your mouth, part your teeth and take 4 slow quiet breaths in and out through your mouth. 

When you go to do the first “ uhum “ sound , aim to put the vibration on your mouth – lightly push the sound from there. Aim not to squeeze the Larynx at the same time, just bring the sound from the lips.

Remember the open mouth breathing posture and start off in this position before you voice any of the vowels or the vowel phrases. Take a little breath in each time before you speak and then as you voice, the breath and voice come out through the mouth at the same time. Maintain a light smile with the teeth apart to assist with this. 
It may also help if you slow down the exercises to allow you to get the forward face placement .

Be careful not to raise the pitch too high too soon. This may be contributing to tension – aim for 155 Hz – 170 Hz. See how that feels and sounds. From there, if necessary, you can increase the pitch a little more. It is usually unnecessary to use a pitch that is higher than 200 Hz. 

If your voice is hoarse – and has been husky or croaky for more than 2 weeks, please ask your doctor to refer you to an Ear Nose & Throat ( ENT) Doctor so that they can assess your Larynx ( you can refer yourself to a private ENT if you prefer)as any persistent hoarseness needs to be checked out .