Commentary for Kiddushin 139:17
נשדר ליה מר שלמא לילתא א"ל הכי אמר שמואל קול באשה ערוה אפשר ע"י שליח א"ל הכי אמר שמואל
'Is not safsal, as used by t Rabbis, or iztaba, as commonly used,<span class="x" onmousemove="('comment',' Others reverse it.');"><sup>27</sup></span> good enough? ' he asked.' Will you partake of ethronga [citron],' he proceeded, 'Thus did Samuel say,' was his reply: 'he who says 'ethronga', is a third [puffed up] with arrogance: either ethrog, as it is called by the Rabbis, or ethroga, as it is popularly called.' 'Will you drink anbaga [cup of wine]? ' he asked him.' Are you then dissatisfied with isharagus, as it is called by the Rabbis, or anpak, as it is popularly pronounced? ' he reproved him.' Let [my daughter] Donag come and serve drink,' he proposed.' Thus said Samuel,' he replied: 'One must not make use of a woman.' '[But] she is only a child!' - 'Samuel distinctly said: One must make no use at all of a woman, whether adult or child.' 'Will you send a greeting to [my wife] Yaltha,' he suggested.' Thus said Samuel,' he replied, [To listen to] a woman's voice is indecent.' 'It is possible through a messenger? ' 'Thus said Samuel,' he retorted
Daf Shevui to Kiddushin
R. Nahman then suggests R. Yehudah send greetings to his wife, Yalta. R. Yehudah, remarkably, believes it is improper to even hear a woman’s voice.
Finally, R. Yehudah believes it is improper to even ask after a woman’s welfare.
This source goes way beyond other sources regarding interaction between men and women. There are other sources that consider it improper to hear a woman sing. But this source considers it improper to even hear a woman speak. We should remember that R. Nahman does not seem to have even heard of these prohibitions.