A few years ago, I noticed that train companies in Japan had started using synthesized voices for some announcements on trains and at stations. (Probably the same thing is happening in other places, but I haven't travelled outside Japan for a long time.) The voices were clearly artificial and sometimes made ridiculous mistakes—such as reading the name of the train company JR East in English as “junior east”—but over time I realized that they also had advantages over prerecorded human voices.

Once, I was riding a two-car local train through a rural part of Kyushu when the train was delayed by heavy rain up ahead. Soon there were audio announcements with artificial voices about the delay in Japanese, English, Chinese, and Korean. Both the Japanese and English sounded a bit strange—the English especially because it was clearly machine translated—but the meaning was clear and they served their purpose. (I couldn't assess the Chinese or Korean.)

The pitch of the artificial voices must have been chosen for good audibility in a noisy environment, as they were easier to understand than most live announcements by human conductors on trains.

Professional human voice actors certainly would have been better, but there is no way they could have been arranged at a reasonable cost for up-to-the-minute train delay announcements in even one language, let alone four.