How to change voice

How do I change my code voice. I have it able to talk but I want it to be able to change its voice.

[Walter Roberson]

Are you looking to do pitch shifting?

[Rainaire Hansford]

Like from Boy to girl voice maybe to a child like voice.

[Walter Roberson]

MATLAB does not have a built-in routine for that purpose. You will need to do some research to figure out more exactly what you want. See for example https://www.researchgate.net/publication/314137171_Gender-related_Frequency_Characteristics_in_Children%27s_Speech