She has no choice but to study in a mixed environment – can she comment and debate in front of males?

Firstly: 

It is not permissible for a woman to work or study in a mixed university, because of the evils and haraam things that result from that, as is obvious to everyone. We have discussed the evidence for the prohibition on mixing in question no. 1200. 

In Fataawa al-Lajnah al-Daa’imah (12/156) it says: Mixing between men and women in schools and elsewhere is a great evil that affects religious commitment and worldly affairs. It is not permissible for a woman to study or work in a place where there is mixing between men and women, and it is not permissible for her guardian to give her permission to do that. End quote. 

There is no obligation to obey one's parents with regard to studying in a mixed environment, because there is no obedience to any created being if it involves disobedience towards the Creator. The Prophet (peace and blessings of Allah be upon him) said: “There is no obedience if it involves sin; obedience is only with regard to that which is right and proper.” Narrated by al-Bukhaari (7257) and Muslim (1840). 

Secondly: 

It is permissible for a woman to speak in the presence of non-mahram men in cases of necessity, subject to the condition that the speech is straightforward and serious and there is no softness, temptation or provocation in her voice. Her voice is not ‘awrah according to the correct scholarly view. Women used to speak to the Prophet (peace and blessings of Allah be upon him) and ask him questions, and they used to speak to the Sahaabah about their needs, and they were not denounced for doing so. Rather they were forbidden to be soft in speech as Allah says (interpretation of the meaning): 

“then be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery) should be moved with desire, but speak in an honourable manner”

[al-Ahzaab 33:32]

al-Qurtubi (may Allah have mercy on him) said in his Tafseer: Allah commanded them to make their speech serious and straightforward, and their posture and gestures should not convey and wrong ideas, as the Arab women used to do when speaking to men, by making the voice soft and gentle, like the speech of immoral women and prostitutes; He forbade them to do that. End quote. 

It says in Mughni al-Muhtaaj (4/210), a book of Shaafa’i fiqh: The woman’s voice is not ‘awrah, and it is permissible to listen to it if there is no fear of fitnah, but it is recommended for her to make her voice unappealing if there is a knock at the door, so she should not answer in a gentle voice, rather she should make it harsh by putting her hand over her mouth. End quote. 

It says in Kashshaaf al-Qinaa’ (5/15), a book of Hanbali fiqh: The voice (of a non-mahram woman) is not ‘awrah. It says in al-Furoo’ and elsewhere: according to the more correct opinion, it is haraam to gain pleasure from listening to it, even if she is reciting Qur’aan, for fear of fitnah. End quote. 

It says in Fataawa al-Lajnah al-Daa’imah (17/202): The woman’s voice is not haraam in and of itself, and it is not haraam to listen to it unless there is some softness and gentleness in speech. It is haraam for a woman to speak in such a manner to anyone other than her husband, and it is haraam for men other than her husband to listen to it, because Allah says (interpretation of the meaning): 

“O wives of the Prophet! You are not like any other women. If you keep your duty (to Allah), then be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery) should be moved with desire, but speak in an honourable manner”

[al-Ahzaab 33:32]

This is the basic principle and guideline with regard to women’s speaking to men. But if a woman has the misfortune to be studying in a mixed university, she should reduce the evil as much as she can, so she should not debate with men or allow any opportunity to speak to her or get to know her, even if that leads to her getting lower grades. Warding off evil takes precedence over seeking benefits. She should also cover herself fully, so that not even her face and hands can be seen, and attend as little as possible, until Allah grants her a way out. 

See also questions no. 8827 and 47554. 

We ask Allah to help you to obey Him and do that which pleases Him. 

And Allah knows best.