Hello DWinkler,
Welcome to the Microsoft Q&A and thank you for posting your questions here.
I understand that you would like to get information on the languages that are supported by the "multilingual" voices.
You can use the Azure Speech SDK https://learn.microsoft.com/en-us/azure/ai-services/speech-service/language-support to query the available voices and their supported languages.
Also, you can use the sample code below to fetch the list of voices and their supported languages using the REST API.
using System;
using System.Net.Http;
using System.Threading.Tasks;
class Program
{
static async Task Main(string[] args)
{
var subscriptionKey = "YourSubscriptionKey";
var region = "YourRegion";
var endpoint = $"https://{region}.tts.speech.microsoft.com/cognitiveservices/voices/list";
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", subscriptionKey);
var response = await client.GetAsync(endpoint);
var content = await response.Content.ReadAsStringAsync();
Console.WriteLine(content);
}
}
}
I hope this is helpful! Do not hesitate to let me know if you have any other questions.
Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful.