In Rabbi Mendel Shapiro's "Qeri’at ha-Torah by Women: A Halakhic Analysis", he includes a section on kol 'ishah, running pp. 40-41 and pp. 41-43, nn. 228-230 (yes, one of the annoyances of the editing of the article to me was that footnotes to sections in the text were on one or two pages ahead). A big selection of that small section is the following (pp. 40-41):
The question of whether qeri’at ha-Torah by women in accordance with the prescribed musical notations (ta`amei ha-miqra) violates qol ishah has not, to my knowledge, been directly addressed by poseqim. There is, however, ample collateral evidence that normative halakhah does not prohibit the practice on this ground. First, as R. Ovadiah Yosef points out, the Talmud’s declaration that women may not read the Torah because of kevod ha-tsibbur (sic), and for no other reason, is strong evidence that the rabbis did not regard qol ishah as a relevant consideration.The footnote at the end of this selection refers the reader to two selections from R' Yosef's Yehaveh Da'at, the latter of which is not particularly relevant to kol 'ishah. The first selection is a brief quote from the third section, the 51st chapter (I am trying to access Spertus right now to get the full text of the responsum, but I think Spertus' Bar Ilan feature is down for the time being):
(Yes, by the way, he wrote כבוד הצבור and not כבוד צבור.)...ומכל מקום, קשה לי מהגמרא "הכל עולים לקריאת התורה למנין שבעה אפילו אשה וקטן, אבל אמרו חכמים אשה לא תקרא בתורה מפני כבוד הצבור", הרי שלא חששו לאסור משום קול באשה ערוה, אף על פי שסתם קריאה בתורה עם טעמי המקרא. וצ"ע....And in any event, it is difficult for me from the Talmudic statement "Everybody ascends to the reading of the Torah for the counting of seven, even a woman or a minor, but [the] Sages said a woman should not read of the Torah on account of the congregation's honor" - behold, they were not concerned to forbid because of "a woman's voice is a nakedness", even though that a normal reading of the Torah is with cantillation. And [this matter] requires looking into.
I must point out, however, that the reason that the Sages that were quoted in the beraisa (on Megillah 23a) did not mention the woman's voice issue is because it had not yet come about. The kevod zibbur issue was brought up by tannaim, the woman's voice issue came about at the beginning of the amoraic period, derived by Shmuel (Berakhos 24a (and also quoted by one of his students in Kiddushin 70a)) : "קול באשה ערוה, שנאמר 'כי קולך ערב ומראך נאוה'" ("A woman's voice is a nakedness, as it is said, 'because your voice is sweet and your appearance is pleasing.'")
However, it is possible that the stammaim could have inquired about this issue, but I'll leave that be for now (thus, it could be that even where a congregation waives their honor, there would still be an issue of women singing [publicly] - but I'm not going to get into that).