Hadith: The Prophet (may Allah's peace and blessings be upon him) used to recite Al-Fātihah followed by another Sūrah in the first two Rak‘āhs of the Zhuhr prayer and used to recite only Al-Fātihah in the last two Rak‘āhs of it. Sometimes a verse or so was audible

عن أبي قتادة رضي الله عنه : «أن النبي صلى الله عليه وسلم كان يقرأ في الظهر في الأوليين بأم الكتاب، وسورتين، وفي الركعتين الأخريين بأم الكتاب ويسمعنا الآية، ويطول في الركعة الأولى ما لا يطول في الركعة الثانية، وهكذا في العصر وهكذا في الصبح».
[صحيح] - [متفق عليه]

Abu Qatādah (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) used to recite Al-Fātihah followed by another Sūrah in the first two Rak‘āhs of the Zhuhr prayer and used to recite only Al-Fātihah in the last two Rak‘āhs of it. Sometimes a verse or so was audible. He used to prolong the first Rak‘ah more than the second and used to do the same in the ‘Asr and Fajr prayers.
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

This noble Hadīth indicates that during the prayers with inaudible recitation such as Zhuhr and ‘Asr, one should recite Sūrat al-Fātihah with another Sūrah in the first two Rak‘āhs, and recite Sūrat al-Fātihah only in the last two Rak‘āhs exactly as done in the audible prayers. There is no harm if one raises his voice a little for the purpose of teaching others.