Can I use the sound files, generated by the Google Cloud Text-to-Speech freely?
<p>Google sells access to their TTS service at <a href="https://cloud.google.com/text-to-speech/" rel="noreferrer">https://cloud.google.com/text-to-speech/</a>. They advertise that you can use it for free, if you use less than 4 million letters (1 million for WaveNet voices).</p>

<p>I couldn't find any information regarding the license terms of the generated audio files. So, what may I do with the generated sound files? I mean often you need the same sounds again and again. May I cache the sound files?  May I play them to the public? Redistribute them with my app? Offer them as a download? Sell them?</p>

<p>To use the TTS service you have to accept the Google Cloud Platform Terms of Service (<a href="https://console.cloud.google.com/tos?id=cloud" rel="noreferrer">https://console.cloud.google.com/tos?id=cloud</a>). I think the most relevant part is the following section:</p>

<blockquote>
  <p>5.1 Intellectual Property Rights. Except as expressly set forth in this Agreement, this Agreement does not grant either party any rights,
  implied or otherwise, to the other’s content or any of the other’s
  intellectual property. As between the parties, Customer owns all
  Intellectual Property Rights in Customer Data and the Application or
  Project (if applicable), and Google owns all Intellectual Property
  Rights in the Services and Software.</p>
</blockquote>

<p>Just at the offset this does not constitute legal advice, just some opinions I have on this point. Technically, you would <strong>not</strong> be prohibited to generate speech and use it however you like. Under normal circumstances any output generated by the system that does not contravene the service agreement would be your intellectual property. This would include the text and speech generated. Once you go about the request limit you would naturally be required to pay, but until that time you can use the service as a paying customer. </p>

<p>Just to clarify this point I would like to make reference to the <a href="https://cloud.google.com/terms/" rel="nofollow noreferrer">service license agreement</a>, clause 3, which make reference to the following prohibitions:</p>

<blockquote>
  <p>(a) copy, modify, create a derivative work of, reverse engineer,
  decompile, translate, disassemble, or otherwise attempt to extract any
  or all of the source code of the Services (subject to Section 3.4
  below and except to the extent such restriction is expressly
  prohibited by applicable law); (b) use the Services for High Risk
  Activities; (c) sublicense, resell, or distribute any or all of the
  Services separate from any integrated Application; (d) create multiple
  Applications, Accounts, or Projects to simulate or act as a single
  Application, Account, or Project (respectively) or otherwise access
  the Services in a manner intended to avoid incurring Fees or exceed
  usage limits or quotas; (e) unless otherwise set forth in the Service
  Specific Terms, use the Services to operate or enable any
  telecommunications service or in connection with any Application that
  allows Customer End Users to place calls or to receive calls from any
  public switched telephone network; or (f) process or store any
  Customer Data that is subject to the International Traffic in Arms
  Regulations maintained by the Department of State. Unless otherwise
  specified in writing by Google, Google does not intend uses of the
  Services to create obligations under HIPAA, and makes no
  representations that the Services satisfy HIPAA requirements. If
  Customer is (or becomes) a Covered Entity or Business Associate, as
  defined in HIPAA, Customer will not use the Services for any purpose
  or in any manner involving Protected Health Information (as defined in
  HIPAA) unless Customer has received prior written consent to such use
  from Google.</p>
</blockquote>

<p>Similarly, as specified <a href="https://cloud.google.com/terms/service-terms#12-google-cloud-platform-machine-learning-group-and-google-cloud-machine-learning-engine" rel="nofollow noreferrer">here</a>:</p>

<blockquote>
  <p>Customer will not, and will not allow third parties to: (i) use these
  Services to create, train, or improve (directly or indirectly) a
  similar or competing product or service or (ii) integrate these
  Services with any applications for any embedded devices such as cars,
  TVs, appliances, or speakers​ without Google's prior written
  permission. These Services can only be integrated with applications
  for the following personal computing devices: smartphones, tablets,
  laptops, and desktops. In addition to any other available remedies,
  Google may immediately suspend or terminate Customer's use of these
  Services based on any suspected violation of these terms, and
  violation of these terms is deemed violation of Google's Intellectual
  Property Rights. Customer will provide Google with any assistance
  Google requests to reasonably confirm compliance with these terms
  (including interviews with Customer employees and inspection of
  Customer source code, model training data, and engineering
  documentation). These terms will survive termination or expiration of
  the Agreement.</p>
</blockquote>

<p>You should also take a look at <a href="https://cloud.google.com/terms/aup" rel="nofollow noreferrer">this</a> and <a href="https://cloud.google.com/text-to-speech/sla#sla_exclusions" rel="nofollow noreferrer">this</a>.</p>

<p>However, as per the terms of the agreement the speech generated would be your intellectual property, unless otherwise specified.</p>

<p>Good luck!</p>

licensing