Speech engine: The technology behind text to speech

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Cliff Weitzman
By Cliff Weitzman Dyslexia & Accessibility Advocate, CEO/Founder of Speechify in VoiceOver on April 22, 2023
Uncover the fascinating technology behind speech engines and text to speech, from how they work to the best pick.

    Speech engine: The technology behind text to speech

    A speech engine is a computer program that synthesizes human-like speech from written text. This technology has come a long way since its inception, and today it has many use cases across various industries. In this article, we will delve into the different types of speech engines, how they work, and their use cases.

    Types of speech engines

    There are two main types of speech engines: rule-based and statistical. Rule-based speech engines use a set of predefined rules to generate speech. They work by breaking the text into smaller units and applying rules to generate speech sounds. In contrast, statistical speech engines use machine learning algorithms to learn from a dataset of recorded human speech and generate speech that sounds more natural.

    How does a speech engine work?

    Speech engines work by converting written text into spoken words. When a user inputs text, the speech engine uses its built-in text to speech (TTS) engine to analyze the text and determine the pronunciation of each word. It then generates the corresponding speech sounds and outputs them through a speech output device, such as speakers or headphones.

    Use cases for speech engines

    Synthetic voices are created using speech synthesis technology and are used in a wide range of applications, including assistive technology, automated customer service, and entertainment. Some speech engines offer pre-built templates for common use cases, such as voice-enabled chatbots or virtual assistants. Speech engines can also be used to provide voice notifications in a wide range of contexts, from medical devices to smart home assistants. Here are a few more use cases across various industries, including:

    1. Accessibility: Speech engines make it possible for people with visual impairments to access written content.

    2. E-learning: Speech engines can be used to convert written content into audio, making it easier to make tutorials for learners to consume.

    3. Contact centers: Speech engines can be used in contact centers to automate responses to frequently asked questions.

    4. Customer experiences: Speech engines can be used to enhance customer experiences, such as providing audio feedback in response to user actions.

    5. Documentaries: Speech engines can be used to provide voice-over for documentaries.

    6. Video games: Speech engines can be used to provide voice-overs for game characters.

    7. Dubbing: Speech engines can be used for dubbing foreign-language films or TV shows.

    8. Podcasts: Speech engines can be used to create podcasts by converting written scripts into audio.

    Qualities you should look for in a speech engine

    One of the primary functions of a speech engine is speech synthesis, which involves converting written text into spoken words. A great speech engine should provide high-quality playback of synthesized speech, with options for controlling the speed, volume, and other parameters. When considering a speech engine, it’s also important to evaluate the functionality it offers. This includes features such as natural-sounding voice output, real-time speech recognition, and the ability to handle different languages. It’s also important to note that high-quality speech synthesis is critical for applications such as automated customer service and assistive technology for people with disabilities. To ensure that a speech engine is of high quality and meets industry standards, it’s important to look for certifications such as ISO 9001 or ISO 27001.

    Speechify – The #1 speech engine

    Speechify is an example of a speech engine that uses machine learning to generate natural-sounding speech. More specifically, it provides a text to speech TTS engine that converts written text into high-quality natural-sounding speech in real-time. It supports multiple different languages, including but not limited to English, Spanish, and Portuguese, and comes with built-in TTS voices, which can be customized to create a unique and sounding voice.

    Speechify also provides a simple API that developers can use to integrate the TTS engine into their applications, including a mobile SDK for iOS. The engine’s pricing is based on usage.

    If you’re looking for synthetic voices that sound like human voices to add to your platforms, the Speechify API is perfect for you as it offers only the most human-like AI generated voices. Visit Speechify API today and learn more.


    What is the difference between speech recognition and transcription?

    Speech recognition and transcription are closely related technologies, with many speech engines offering both capabilities. Transcription involves converting spoken words into written text, which can be useful for applications such as closed captioning or note-taking.

    What is an example of an open-source speech engine?

    There are many open-source speech engines available, such as the Festival Speech Synthesis System and the eSpeak speech synthesizer.

    Can I use the Speechify API with Android?

    If you’re interested in using the Speechify API in another client like Android, React Native, or Flutter, let us know. We’d be happy to discuss your use case and see how we can help.

    What are the different types of Speech engines?

    Speech engines are available in various forms, including command-line tools, software development kits (SDKs), and Software-as-a-Service (SaaS) solutions. Command-line tools are typically used for simple TTS conversion tasks, while SDKs provide more advanced functionality and can be integrated into custom applications. SaaS solutions offer a cloud-based TTS service that can be accessed through a web interface or API.

    How can I enhance a speech engine?

    To further enhance the speech output, many speech engines support Speech Synthesis Markup Language (SSML). This is a markup language that provides a way to control various aspects of speech synthesis, such as pronunciation, emphasis, and prosody. By using SSML, developers can customize the speech output to better suit their needs.

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    Cliff Weitzman

    Cliff Weitzman

    Cliff Weitzman is a dyslexia advocate and the CEO and founder of Speechify, the #1 text-to-speech app in the world, totaling over 100,000 5-star reviews and ranking first place in the App Store for the News & Magazines category. In 2017, Weitzman was named to the Forbes 30 under 30 list for his work making the internet more accessible to people with learning disabilities. Cliff Weitzman has been featured in EdSurge, Inc., PC Mag, Entrepreneur, Mashable, among other leading outlets.

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