Google Cloud Text-to-Speech 401 Unauthorized using C# HttpClient AuthenticationHeaderValue Bearer with API key

Question

据我所知，Google Cloud 已正确配置。我已经尝试了 API 密钥和服务帐户密钥，但在使用 curl 连接时不断收到 401 Unauthorized。结果 401 未经授权。我没有使用 Google 库，因为我无法为我要构建的这个小应用程序访问它。

public async Task GenerateResponse(Input input, Voice voice, AudioConfig audioConfig, string outputFile)
{
   using (var client = new HttpClient())
   {
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "MyAPIKey");
        var request = new { input = input, voice=voice, audioConfig=audioConfig  };
        var jsonRequest = JsonConvert.SerializeObject(request);
        var content = new StringContent(jsonRequest, Encoding.UTF8, "application/json");
        using (var response = await client.PostAsync("https://texttospeech.googleapis.com/v1/text:synthesize", content))
        {
            response.EnsureSuccessStatusCode();
            using (var audioStream = await response.Content.ReadAsStreamAsync())
            {
                using (var outputStream = File.Create(outputFile))
                {
                    await audioStream.CopyToAsync(outputStream);
                }
            }
        }
    }
}