Assuming you already have a Bluemix account and have added text in the Watson API to the Bluemix workspace, you have credentials to access the API (sedative).
If you requested to use the CURL linux application, it would be something like this
curl -u "xxxxx729-b03f-4403-8adf-c5418ee4ea05":"xxxxxiWtmVoG" "https://stream.watsonplatform.net/text-to-speech/api/v1/synthesize?text=Hello+World" -H "accept: audio/flac" > sound.flac
Using Python, it could be
import requests
headers = {'accept': 'audio/flac'}
r = requests.get('https://stream.watsonplatform.net/text-to-speech/api/v1/synthesize?text=Hello+World', auth=('xxxxx729-b03f-4403-8adf-c5418ee4ea05', 'xxxxxiWtmVoG'), headers=headers)
with open('/home/leo/sound.flac', 'wb') as fd:
for chunk in r.iter_content(1024):
fd.write(chunk)
. http://docs.python-requests.org/en/master/user/quickstart/.
. https://www.ibm.com/smarterplanet/us/en/ibmwatson/developercloud/text-to-speech/api/v1/ text2Speech.