从Google云函数设置Firebase存储的位置路径?

我正在把一个音频文件从Google文本转换成语音,然后把这个文件写到Firebase存储中。我不明白我在哪里指定了存储位置的路径。我试过:

    const bucket = storage.bucket('myProject-cd99d.appspot.com/Audio/Spanish/test.ogg');

但我收到一条错误信息: TypeError: Path must be a string . 以下是云函数:

exports.Google_T2S = functions.firestore.document('Users/{userID}/Spanish/T2S_Request').onUpdate((change, context) => { 
  if (change.after.data().word != undefined) {

    // Performs the Text-to-Speech request
    async function test() {
      try {
        const word = change.after.data().word; // the text
        const longLanguage = 'Spanish';
        const audioFormat = '.mp3';
        // copied from https://cloud.google.com/text-to-speech/docs/quickstart-client-libraries#client-libraries-usage-nodejs
        const fs = require('fs');
        const util = require('util');
        const textToSpeech = require('@google-cloud/text-to-speech'); // Imports the Google Cloud client library
        const client = new textToSpeech.TextToSpeechClient(); // Creates a client

        let myWordFile = word.replace(/ /g,"_"); // replace spaces with underscores in the file name
        myWordFile = myWordFile.toLowerCase(); // convert the file name to lower case
        myWordFile = myWordFile + audioFormat; // append .mp3 to the file name;

        // boilerplate copied from https://cloud.google.com/blog/products/gcp/use-google-cloud-client-libraries-to-store-files-save-entities-and-log-data
        const {Storage} = require('@google-cloud/storage');
        const storage = new Storage();
        const bucket = storage.bucket('myProject-cd99d.appspot.com/Audio/Spanish/test.ogg');

        const request = {     // Construct the request
          input: {text: word},
          // Select the language and SSML Voice Gender (optional)
          voice: {languageCode: 'es-ES', ssmlGender: 'FEMALE'},
          // Select the type of audio encoding
          audioConfig: {audioEncoding: 'MP3'},
        };

        const [response] = await client.synthesizeSpeech(request);
        // Write the binary audio content to a local file
        // response.audioContent is the downloaded file
        await bucket.upload(response.audioContent, {
          metadata: 'public, max-age=31536000'
        })
        .then(function() {
          console.log('Uploaded file.');
        })
        .catch(function(error) {
          console.error(error);
        });
      }
      catch (error) {
        console.error(error);
      }
    }
    test();
  } // close if
  return 0;
});

我还需要返回main函数。