The Prophet's (ﷺ) recitation was loud enough for one who was in the inner chamber to hear it when he was in the house.
Sunan Abi Dawud Book 5, Hadith 78
← Previous Hadith A man asked the Messenger of Allah (ﷺ) about the prayer at night. The Messenger of Allah (ﷺ) said: Prayer during the night should consist of pairs of rak'ahs, but if one of you fears the morning is near he should pray one rak'ah which will make his prayer an odd number for him.

Sunan Abi Dawud Book 5, Hadith 77 Next Hadith → The Prophet's (ﷺ) recitation at night was partly in a loud voice and partly in a low voice.

Abu Dawud said: The name of Abu Khalid al-Walibi is Hurmuz.

Sunan Abi Dawud Book 5, Hadith 79