TypeError [ERR_HTTP_INVALID_HEADER_VALUE]: Invalid value "undefined" for header "authorization"
    at ClientRequest.setHeader (_http_outgoing.js:473:3)
    at new ClientRequest (_http_client.js:194:14)
    at Object.request (https.js:281:10)
    at WebSocketClient.connect (/Users/sodeimo/node_modules/websocket/lib/WebSocketClient.js:254:56)
    at new W3CWebSocket (/Users/sodeimo/node_modules/websocket/lib/W3CWebSocket.js:62:18)
    at RecognizeStream.initialize (/Users/sodeimo/node_modules/watson-developer-cloud/lib/recognize-stream.js:201:37)
    at /Users/sodeimo/node_modules/watson-developer-cloud/lib/recognize-stream.js:399:23
    at RecognizeStream.setAuthorizationHeaderToken (/Users/sodeimo/node_modules/watson-developer-cloud/lib/recognize-stream.js:475:13)
    at RecognizeStream._write (/Users/sodeimo/node_modules/watson-developer-cloud/lib/recognize-stream.js:374:14)
    at doWrite (_stream_writable.js:410:12)

'use strict';
require('dotenv').config({ silent: true }); // optional, handy for local development
var SpeechToText = require('watson-developer-cloud/speech-to-text/v1');
var LineIn = require('line-in'); // the `mic` package also works - it's more flexible but requires a bit more setup
var wav = require('wav');

var speechToText = new SpeechToText({
    url:'https://stream.watsonplatform.net/speech-to-text/api',
    api_key:'hoge'

});

var lineIn = new LineIn(); // 2-channel 16-bit little-endian signed integer pcm encoded audio @ 44100 Hz

var wavStream = new wav.Writer({
    sampleRate: 44100,
    channels: 2,
});

var recognizeStream = speechToText.recognizeUsingWebSocket({
    content_type: 'audio/wav',
    interim_results: true
});

lineIn.pipe(wavStream);

wavStream.pipe(recognizeStream);

recognizeStream.pipe(process.stdout);