I came across a good online essay by R. Howard Jachter about the practical aspects of kol ishah in contemporary society.
Most of the essay is a discussion of contemporary halakhah, but he concludes with the following important statement:
Observance of the Kol Isha prohibition is quite challenging for us as this prohibition runs counter to the prevailing Western culture. In todayâ€™s promiscuous society where outrageous behavior is deemed acceptable, a womanâ€™s singing voice appears innocuous. Moreover, the general culture views this prohibition offensive and demeaning to women. We are challenged to hold firm to our beliefs against the flow of the general cultural tide. This is one of the issues that we must part company with the rest of society, just as Avraham Avinu and Yitzchak Avinu parted with their two servants on the road to Akeidat Yitzchak. Rav Yehuda Amital told me that we should strictly observe the Kol Isha prohibition today precisely because of the deterioration of the moral standards of western society.