Assalamualaikum ustaz. There are some congregants who recited too loudly that sometimes it distracts and disturb the other congregants who are praying. Hope to get your advice and opinion on this issue.
Waalaikumussalam wrt. wbt.,
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.
Requisites in prayer are divided into three; the qalbi (heart), qauli (recitation or speech) and fi’li (action) requisites. Among the main matters in prayer is the qauli requisites. It is named as qauli requisites because these requisites are obligatory to be recited in prayer that it is at least heard by himself.
Syeikh al-Sayyid Abdullah al-Hadrami stated in his book: “(Requisites) Qauliah are five: Takbiratul Ihram at the beginning of prayer, reciting al-Fatihah in every rakaat, tasyahud and praise on the Prophet PBUH and salam, all three are in the final sitting.” 
Thus, from the statement, it can be understood there are five qauli requisites, which are:
- Takbiratul ihram
- Surah al-Fatihah recitation
- The final tasyahhud recitation
- Praise and salutation for the Prophet Muhammad in the final tasyahhud
All of these qauli requisites should be recited, verbalize and uttered that one’s voice is heard by one’s ears. 
Syeikh Abu Bakar Syata al-Dimyati also emphasized this matter, saying: “(And it is obligatory to hear) the takbiratul ihram can be heard by the praying person himself, if he has good hearing and nothing hindering his hearing comes, for instance, loud or noisy sound, (the whole qauli requisite) from al-Fatihah, final tasyahhud and salam.” 
While according to Imam al-Nawawi, the minimum recitation for qauli requisites is a low-voiced recitation where only he can hear it. 
In the book al-Majmu’, he stated: “For a makmum, it is sunnah to lower his voice whether when he is praying alone or in a congregation. And the minimum is for his voice to be heard by his ears if he has sound hearing and nothing is preventing him from reciting them. This includes the recitation of al-Fatihah, surah, tasbih, tasyahhud, salam, supplication and others. Regardless of whether the recitation is obligatory or sunnah. All of them will only be considered if he hears what he recites.” 
Syeikh Muhammad al-Zuhaili also stated: “He should hear (what he recites) himself if he has a sound hearing and nothing is hindering it such as other noise distractions and others. If he has speech debility or is mute, then he should move his mouth according to his capability. Move both his lips and uvula as he is capable.” 
Likewise, this is emphasized in the book al-Fiqh ala al-Mazahib al-Arba’ah, which states: The answer for this question (is a person conditioned to listen to his recitation of al-Fatihah), three of the mujtahid imams agreed that is a person doesn’t hear his recitation, then he is considered to have not recited it. 
In answering the above issue, we state the following:
Basically, a makmum is restricted from reciting loudly behind the imam, moreover, he should lower his voice so that it can only be heard by himself. Imam al-Nawawi stated this fact in al-Majmu` Syarh al-Muhazzab (3/364): “When we present our opinion that it is obligatory for a makmum to recite (al-Fatihah) during jahar prayer (recited loudly such as subuh and Friday prayers), (however) it is makruh for a makmum to increase (his voice for the recitation) that it would disturb his neighbour (people near him), rather he should lower his voice (for his recitation) until it can only be heard by himself if he is a sami’ (not deaf) and nothing is hindering (preventing the recitation) from loud noise and others, for it is the least sufficient recitation.”
Although the above statement shows that the restriction is makruh (discouraged), however, some Syafieyyah scholars emphasized its prohibition when it disturbs others, for it harms others. Imam Ba Fadhl said in al-Muqaddimah al-Hadhramiah: “And it is prohibited to increase one’s voice if it causes tasywisy (disturbance to others) to others.”
This difference of opinion is harmonized by Imam Ibn Hajar al-Haitami in al-Minhaj al-Qawim (pg. 125-126): “[And it is prohibited] on everyone to increase one’s recitation during and outside of prayer [if it disturbs others] like a person who is praying, reciting al-Quran, or sleeping, for it harms and refers to a disruptive speech even if it is towards a fasiq person. What is stated from the prohibited ruling is the apparent meaning (from the al-Muqaddmah al-Hadhramiah evidence), however, the prohibition is denied with the words (of Imam al-Nawawi) in al-Majmu’ and others, hence, it is as though the sarih (clear) is that it is not prohibited, except when one tries to assemble (both the opinions) with the possibility that it is makruh if the tasywisy (disturbance) is just minor.”
This restriction is relevant because Islamic law stands on the principle of preventing harm. A hadith of the Prophet PBUH became the basis of an Islamic legal maxim which states:
لَا ضَرَرَ وَلَا ضِرَارَ
“There shouldn’t be harm of reciprocation of harm.” 
The same is stated in Busyra al-Karim (pg.286), al-Allamah al-Habib Ba `Isyn agreed with the harmonization and included a situation if there isn’t any debility: “[And it is prohibited] on a person who is praying, on the condition that he doesn’t have any debility, to [increase his recitation] in prayer and outside of it [if it disturbs others] such as a person who is praying, reciting al-Quran and others, for it is harming others.
And taken from this (understood) from the disturbing speech includes the restriction that even if happens to a fasiq, for it is unknown except it. (This prohibition) only if the disturbance is excessive. If it isn’t excessive, then it is makruh. Through this approach, the khilaf (stated above) is harmonized. Although if there is debility, such as a noisy environment which forces the person to raise his voice, then he recited based on this situation, then it is neither makruh nor prohibited.” 
We’d also like to state several situations where a makmum can raise his voice. Among them are:
- Muballigh voice. If the voice of the imam is too low that there is concern that the congregants at the back wouldn’t be able to hear it, it is sunnah for the makmum to act as the muballigh (conveyor) of the imam’s voice by raising his voice. Syeikh al-Jamal in his Hasyiah (1/367): [Imam Zakariyya al-Ansari said: And it is sunnah to raise one’s voice for others to hear for the imam and muballigh] which means if there’s a need to do so, as stated by Imam al-Ramli, for it is a dhikr which signals changes/moving in action.”
- Reciting Amin loudly after the Imam’s al-Fatihah recitation. Imam al-Nawawi in his book al-Majmu’ (3/371) stated: If the prayer is a sirriyyah prayer (a prayer of which its recitation is recited in a lowered voice such as Zuhur prayer), then the imam and others should recite the amin in a low voice following the situation if the recitation (of al-Fatihah). If it is jahriyyah (prayer with a loud recitation such as Subuh prayer) and it is recited loudly during the recitation (al-Fatihah) then it is encouraged for the makmum to raise his voice when reciting Amin without khilaf as stated by Imam al-Syafie and this is agreed by the Ashab.
Thus, according to the above discussion, we can conclude the following points:
- Makruh for a makmum to recite loudly during congregational prayer because it may disturb others and it is sunnah for them to recite it in a low voice so that he can hear it.
- If the makmum recite loudly that it disturbs others and that it disturbs people beside him from reciting their recitation in prayer then this is
- It is neither prohibited nor makruh if it doesn’t disturb others and there is no debility such as noisy or loud sounds. However, it is not obligatory to raise one’s voice if there is loud sounds, it is enough for him to recite in a voice he usually recites in normal situations.
- It is sunnah for a makmum to raise his voice when reciting amin after the recitation of al-Fatihah of the imam in jahriyyah prayer, including during qunut and for a makmum who is the
Hopefully, this explanation will benefit us all.
 See Safinah al-Naja pg. 44
 See Hasyiah al-Bujairimi ‘ala Syarh Manhaj al-Tullab, 1/189
 See I`anatu al-Talibin, 3/295
 See Raudhah al-Talibin wa Umdah al-Muftin, 1/242
 See al-Majmu’ Syarh al-Muhazzab, 3/394
 See al-Mu’tamad fi al-Fiqh al-Syafie, 1/241
 See al-Fiqh ‘ala al-Mazahib al-Arba’ah, 1/201
 Narrated by Ibn Majah (2341)
 See Busyra al-Karim, pg. 286