Ruling on the imam changing his voice when saying the takbir at the tashahhud

Question:
What is the ruling on changing the voice of the takbir before the first and second tashahhud so that the worshippers know that the imam is about to sit for the tashahhud? Is that permissible?

Answer:
We know of nothing regarding it. The important thing about the voice of the one who calls to prayer is that he alerts the people so that they raise and lower their voices. Whether it is a specific melodic quality or not, the important thing is that he raises his voice to the extent that the intended purpose is achieved for the ma'mum (those praying behind him). If there is a sign in his voice indicating that he is sitting for the first and final tashahhud, there is no harm in that, so that they do not stand up and rise, and so that they know.

Question: Who intentionally changes the voice?

Answer: We know of nothing regarding it. There is no blame in that, because the intended purpose is to benefit the congregation by guiding them.