Google cloud speech plugin with unity出错

using UnityEngine;
using Google.Cloud.Speech.V1;
using Grpc.Core;

public class SpeechToText : MonoBehaviour
{
    private SpeechClient speechClient;

    void Start()
    {
        // 初始化SpeechClient
        speechClient = SpeechClient.Create();
    }

    void Update()
    {
        // 捕获音频并进行转录
        if (Input.GetKeyDown(KeyCode.Space))
        {
            RecognizeSpeechAsync();
        }
    }

    private async void RecognizeSpeechAsync()
    {
        var config = new RecognitionConfig
        {
            Encoding = RecognitionConfig.Types.AudioEncoding.Linear16,
            SampleRateHertz = 16000,
            LanguageCode = "en-US"
        };

        var audio = RecognitionAudio.FromMicrophone(); // 使用麦克风输入

        var response = await speechClient.RecognizeAsync(config, audio);

        foreach (var result in response.Results)
        {
            foreach (var alternative in result.Alternatives)
            {
                Debug.Log("Transcript: " + alternative.Transcript);
            }
        }
    }

    void OnDestroy()
    {
        speechClient.ShutdownAsync().Wait();
    }
}