Voices that are considered sexy In-Universe. For women, husky ones are popular; breathy, low Marilyn Monroe -esque voices are iconic. For men, deep baritones with sonorous intonations often are used. Bassos are rarer but can also fit the bill. A popular variation is the "Siren Switch," where the speaker isn't nearly as sexy as their voice.
In ancient Rome, women were forbidden from speaking in the forum, but during the civil wars and political tumult of the late republic, the rules about public oration loosened a bit, which is why we know of Caia Afrania, a Roman from the first-century BC who insisted on speaking for herself when she came before the court. She evidently enjoyed pleading cases, so much so that she acted as a lawyer for others, which was common among men but unheard of for women. The hostility she suffered for this perceived impudence was tremendous. Rome passed a law — in which she was referred to as improbissima fema, the infamous woman — forbidding women to plead cases other than their own. The rancor was directed not just at the fact of her speech but at the sound of her voice.
Even more so, my biggest turn off is a bad voice. He was my go-to, typical type personified. We had met online, and when he arrived at the bar, he looked exactly the same as his pictures. However, as soon as he opened his mouth, I knew it was game over. I was completely certain that no amount of great personality and talking could ever make his voice grow on me.