Is the prohibition of cutting off the Madd and vibrating the Ghunnah general, or specific to what causes deviation from the established measure?

Ibn al-Jazari interpreted "al-tatneen" in ghunnah as an exaggeration of it. As for the cutting of the madd, no interpretation of it has been found with him or with the early scholars. In general, transitioning between sound registers in madd or ghunnah is permissible as long as it does not reach "al-tamteet" which alters the pronunciation. What is forbidden is "tar'eed al-mudood," which means to make one's voice tremble like someone in pain.