All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is not valid, in the Sharee'ah, for a woman in the state of Ihram to recite the Talbiyah aloud beyond the level of being audible to herself. In his Al-Mughni, Ibn Qudaamah says relating from Ibn ‘Abdul-Barr, “The scholars agree unanimously that it is an act of the Sunnah for the woman not to raise her voice. She just has to make herself hear her voice and no more. That is the opinion of ‘Ata’, Maalik, Al-Awza‘i, Ash-Shaafi‘i and the Hanafi scholars.”
According to Al-Mardawi in Al-Insaf:
"It is an act of the Sunnah for the woman to not raise her voice. That is the consensus of the scholars, as was reported by Ibn Al-Munthir. It is unfavorable for her to raise her voice beyond the level of being audible to her female companion by her side. That is the correct opinion of the Hanbali school."
Allaah Knows best.