Listening to woman singing

Is a man allowed to listen to music of a popular woman singer that is taped?

There is a disagreement among Poskim over this question. On the stringent side is Rav Betzalel Stern (Responsa B'tzel haChochma 5;49) who prohibits listening even to the voice of a woman one doesn't know (Rav Stern is strict even in regards to certain telephone conversations). Rav Ovadiah Yosef (Yabiah Omer vol. 1 Orach Chayim 6) prohibits when the woman is known to the man, while Rav Waldenberg (Tzitz Eliezer 5;2) does not recognize electronic sound as being within the prohibition, but cautions against having intention for sensual pleasure when listening.