Cloud Speech-to-Text REST API v2

Create or select a Google Cloud project, enable Cloud Speech-to-Text, then obtain an OAuth 2.0 access token using Google Cloud authentication. The easiest local path is to follow Authenticate for using REST or Authenticate for using client libraries. For CLI use, sign in with `gcloud auth login` or use a service account / Application Default Credentials as described in Authentication methods at Google. Speech discovery documents list the cloud-platform scope.

In Google Cloud Console, create an API key following Manage API keys. Then use it as the key query parameter as described in Use API keys to access APIs. The Speech discovery document says the key parameter is required unless you provide an OAuth 2.0 token.