According to the 'Arabic language tar-jee' means to return or repeat. It means that the sound is repeated. The tafseer (commentary) of it is related by Sayyidina 'Abdullah bin Mughaffal Radiyallahu 'Anhu himself as Aa-Aa. Some of the 'ulama state this means to clear the voice and recite. Sayyidina Rasulullah Sallallhu 'Alayhi Wasallam was very happy on the conquest of Makkah, and it becoming Darrul Islaam, therefore he was reciting with enjoyment. The research of my late father -May Allah fill his grave with nur-is that since Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam was sitting on a camel, its walking and moving made it seem that the sound was being repeated. For this reason Sayyidina 'Abdullah bin Mughaffal Radiyallahu 'Anhu explained is as Aa-Aa and Sayyidina Mu'aawiyah Radiyallahu 'Anhu did not attempt to demonstrate it, because he feared people would begin gathering around him. According to this explanation it will not contradict the following hadith. This humble servant prefers this explanation, because according to the first explanation it will mean to recite clearly and with a good melodious voice, then what fear shall there be of people gathering around. It is necessary to recite the Qur-aan correctly, wherein there is no singing tune. In many ahaadith under diffrent headings it has been stressed that the Qur-aan must be recited with tarteel and a good intonation. I have compiled some of these ahaadith in my kitaab 'Chehl Hadith;. Those who are interested may read it.