Answered by Shaykh Abu Usamah
Can you please answer the following queries:

Al-Salam `Alaykum
1. Regarding the recitation of Ta`awwudh, Tasmiya (saying Bismillah ), Amin in Salah
a) in a loud congregational prayer (as a follower)
The follower will not recite Ta`awwudh and Tasmiya as these are the preliminaries to Qira`a. Since the follower is not reciting he will also not recite these. However he WILL recite Amin inaudibly after the Imam completes Sura al-Fatiha.
b) in a quiet congregational prayer (as a follower)
He will not recite any of the three (Ta`awwudh, Tasmiya, Amin)
c) in an individual prayer
The one praying will recite all three.
2. Loud laughter is defined in the books of Fiqh as ‘that which can be heard by the person praying and those around him’ i.e. ‘in the vicinity’ Laughter is ‘that which only he can hear’ and a Smile is when there is no sound at all.
A smile does not invalidate the prayer nor the wudu. Laughter invalidates the prayer only and loud laughter invalidates both.
a) The above definition is merely to quantify the level of the sound and it does not necessitate that there must be someone physically there to hear it. If the laughter is loud enough that had a person been in the vicinity he would have heard it then this is ‘loud laughter’ and would break the wudu.
b) The same law applies had there been loud background noise in the place of prayer such that in the absence of that noise the sound of laughter would be heard by a person in the vicinity.
(ibn Abidin, Radd al-Muhtar 1.144 ; Fatawa Hindiyya 1.13)
Abu Usama
Durban, South Africa