Is it obligatory to repeat ablution or prayer upon hearing a sound from the anus, without feeling any gas escape, knowing that the sound might be from the colon or from within?

The Prophet, peace and blessings be upon him, intended by his saying: "until he hears a sound or finds a smell," that ablution is not invalidated except by the certain conviction of its invalidation. This hadith is one of the fundamental principles of Islam and a jurisprudential rule, indicating that things are judged to remain in their original state until the contrary is certain, and an incidental doubt has no effect. So, whoever is certain of his purity and doubts its occurrence, this does not harm him until he obtains certainty of its invalidation, such as hearing a sound or finding a smell. If he is certain of invalidation through something other than a sound or smell, his purity is invalidated. If he doubts the nature of the sound, it is not invalidated due to the lack of certainty. Therefore, one must disregard obsessive thoughts, for your purity is not invalidated except by certain conviction that one can swear by, and the default is the continuity of purity. There is no need to repeat prayers unless certainty is obtained.