In our area, Imam starts to make dua with such a voice that muqtadi could know that Imam has started to make dua. And all the muqtadi starts to make dua after listening the voice of Imam (e.g. if he starts dua with alhamdulillahi rabbil a’alameen, he says alhamdulillahi…… with voice and then make entire dua silently).
And he ends dua with voice so that muqtadis could know, and muqtadis also end their dua after listening to his voice.
No one starts making dua before and none completes dua before Imam.
What is the shar’i status of this all described above?
Should Muqtadi not start making dua before Imam?
Should Imam inform muqtadees about his dua by starting it with voice? or he should starts his dua silently?
If one has finished his dua before Imam, should he wait untill Imam finisher? or one should stand up to offer sunnah (if sunnah are after that fardh salah)?
Please clarify the questions and the shari status of the custom of dua described above.