Response: Women are a place for fulfillment of desire for men. They are inclined to them by natural impulses that make them desire and appreciate them. If a woman is flirtatious in her speech, it increases the temptation and desire. For that reason, Allah has ordered the believers, that when they ask anything of women, that they ask from behind a curtain. Allah states,
“And when you ask them, ask them from behind a screen, that is purer for your hearts and for their hearts” (al-Ahzab 53).
He has also prohibited women, when they speak with men, to be flirtatious or soft in their speech in order that those in whose hearts is a disease may not desire them. Allah has stated,
“Be not soft in speech, lest those in whose heart is a disease should be moved with desire” (al-Ahzab 32).
If that was the situation at a time when the believers were strong in their faith, what must be the situation in a time like now when faith has been weakened and very few stick to the religion? You must mix with non-mahram men as little as possible and speak to them but little. You must do so only if there is truly a need to do so and, when doing so, you must not use flirtatious and soft speech, as is stated in the above verse.
Based on that, one can see that the voice, free of soft or flirtatious speech, is not aurah in itself. The women used to speak to the Prophet (peace be upon him) and ask him questions about the religion. Similarly, they used to speak to the male Companion when they needed to do so and no one objected to that.