Blog – Synthesys

Everything you Should Know About Text to-Speech

by Oliver Goodwin | May 3, 2022

Reading Time: 6 minutes

everything you need to know about tts

Have you ever wondered how, when navigating an unfamiliar route, Google Maps can communicate the instructions printed on your computer screen so you don’t have to stare at it while driving? Or how do Apple’s Siri and Google Assistant collect your words and read them aloud? These applications and many more are made possible by a variant of technology called Text-to-speech.

What is Text-to-Speech?

Text-to-speech, to put it simply, is an assistive feature on computers that employs specific methods to read out digital texts aloud in real or simulated voices. 

With a simple call-to-action, text-to-speech reaches for the relevant strings of words and converts them to their audio equivalents to enhance access and/or convenience.

How Does Text-to-Speech Work?

To a rudimentary degree, the method of operation that makes text-to-speech work can be broken down into three distinct levels: text preprocessing, formation of phonemes, and, finally, mutation of phonemes to sound.

Text Preprocessing

This first step involves converting the written texts into words that the computer understands and can interpret in a process called text preprocessing or text normalization. That is, reducing the ambiguity of the digital texts by narrowing each word or character down to the singular most possible way it can be pronounced in the given context. This process is an understanding between input and computer processing to achieve sound compromise and make fewer pronunciation errors. 

Words and characters are pronounced and inflected differently depending on context. The number “1942”, for instance, can be pronounced several ways, from “One thousand, nine hundred and forty-two” to “Nineteen-forty-two” and to “One Nine four Two”. To understand the specific meaning this number carries in the text provided, the computer studies the environing expressions and uses the hedging context to strip the varying meanings to the most valid pronunciation.

Formation of Phonemes

Phonemes are the atoms of every sound that makes up a word. To understand phonemes, think of them this way: the spelling of the word “bag” is composed of three fundamental letters. The pronunciation likewise is composed of fundamental sounds. These fundamental sounds are called phonemes. This second step deals with the possession and cataloguing of every possible individual phoneme in a language’s phonetics.

After processing a word and deciding upon its most likely pronunciation, the computer, having possessed the pronunciation building blocks, disintegrates the word into its phonemes. It, afterwards, proceeds to the third and final step, which is

Mutation of Phonemes to Sounds

After the text has been analysed and disintegrated into its likely phonemes, what next? This is where the voice comes in to produce auditory output.

The voices we hear when our gadgets read our text out to us after all its back-end processes are either real human voices or simulated voices. These outputs are generated employing any of these three distinct approaches: concatenative, formant, and articulatory speech syntheses.

The concatenative speech synthesis synthesises a variety of prerecorded phonemes by actual humans into the relevant phonemes required to produce the sounds corresponding to every word/character in the text.

The formant speech synthesis takes all resonant frequencies–called formants–that make up the human vocals. To put it simply, formats are to human sound, what primary colours are to the entire colour palette. With the three primary colours, any other colour can be produced using the proper mixture. This mechanism holds the same for formants.

Finally, the articulatory speech synthesis uses Artificial Intelligence robots to model human voices and produce realistic sounds with near-perfect frequencies and inflexions.

What is the Purpose of Text-to-Speech?

Text-to-speech exists to solve or subside a diversity of social, geographic, and medical challenges plaguing the world today, some of which include:

1. Visual Impairment

As of October 2022, at least 2.2 billion people lived with vision impairment globally. This number accounts for around 27.85% of the world population today and for the demographic of people with reading difficulties due to bad sight or blindness. With text-to-speech technology, reading becomes possible or much easier for this fold of the world.

2. Illiteracy

Text-to-speech also addresses the challenge facing people who aren’t formally educated but desire access to information. The global literacy rate among adults as of September 2020 was 86.682%, leaving out roughly 13.318% of adults in the world who are unable to read the words they come across. 

With the increasing adoption of text-to-speech technology, this number will significantly reduce. This will even make learning for them easier since text-to-speech offers multi-sensory learning possibilities.

3. Learning Disabilities

Another problem text-to-speech exists to solve is the issue of learning difficulties among students. Challenges such as dyslexia and autism are rife in our present world and are a major drawback to world literacy among kids and even adults.

For example, statistics show that 70-80% of people with poor reading skills are dyslexic, and about one in a hundred kids is autistic. Oft-times, these disabilities persist in their victims because of improper learning medium or inadequate learning tools, both of which can easily be lessened with the use of text-to-speech technology.

4. Speech Impairment

Perhaps, the most famous application of text-to-speech technology in the correction of speech, voice, and language disorders remains the case of Stephen Hawking. However, with a more complex approach to applying text-to-speech technology, kids experiencing language and speech challenges can finally communicate with ease.

What Are the Benefits of Text-to-Speech?

The utilisation of text-to-speech technology offers an abundance of alluring benefits forking towards accessibility, convenience, and productivity. Some of these benefits are highlighted below:

1. Support for Multitasking

With text-to-speech technology, people are no longer constrained by or visually obligated to the pages of text to be read. A person, for instance, can drive while listening to an audiobook as opposed to performing one task at a time, as in the case of actually reading said book.

2. Virtual Assistants

Perfect examples are Apple’s Siri, Amazon’s Alexa, Google Assistant, and Microsoft’s Cortana. These examples are proven and tested to provide the necessary aid when prompted. For example, with Google Assistance, one doesn’t have to have their eyes fixated on their phone’s screen while driving and using Google Maps.

Moreover, virtual assistants help live-alone elderly people in multiple areas, such as providing virtual friendship, reminding them of important tasks, verbal security warnings, etc.

3. Improved Customer Experience

With text-to-speech technology, businesses experience minimised workload on staff and enhanced personalised customer experience. TTS, with AI robots, helps businesses pass the necessary information to their clientele fluidly with few expected errors.

4. For Learning New Languages

With text-to-speech technology, people can easily learn any language they wish to learn. However, while some languages can be learned by reading their words, many more languages have words that don’t sound the way they’re spelt, and this is where TTS steps in. An application of this can be seen in Google Translate, where words can be translated to any language and read out to enhance the learning experience. 

5. Multiple Learning Options

Text-to-Speech technology offers a sufficient range of learning options. Learning media comprises reading, listening, writing, and viewing options. With TTS, kids aren’t necessarily confined to the traditional classroom methods, as they can now access multi-sensory ways of learning.

Types of Text-to-Speech Tools

Text-to-speech tools come in different forms and media, and one’s possession of any depends on the kind of device one uses. These tools are classed based on platform and accessibility, and they include:

1. Web-based Tools

These are TTS tools that come attached to certain websites for added experience. Websites like Google, for instance, can read out input texts out loud with only a button click.

2. Built-in Text-to-Speech Tools

Built-in text-to-speech tools come preinstalled in specific computers of all kinds. Therefore, these devices hardly need additional TTS installation or extension since they adequately carry out their stipulated functions.

3. Text-to-Speech Applications

Unlike devices with built-in TTS tools, some other devices do need app installation to carry out TTS functions. A great example is Synthesys AI voice generator, in which AI-generated voiceovers of variegated male and female voices convert one’s text to realistic, lifelike speech.

4. Text-to-Speech Software Setups

These programs, installed on computers such as laptops and desktops, work similarly to TTS apps to augment learning experience and literacy level.

5. Chrome Text-to-Speech Tools

This ChromeVox Read Aloud setting comes with a Chromebook, which grants accessibility through spoken feedback to its user.

How Text-to-Speech Can Help Kids

We’ve discussed the positive impacts of TTS technology on all and sundry. TTS can, however, exclusively be applied to the learning culture of kids to improve their learning growth. By making kids not only see but also hear what they see, one can:

  1. Make them identify and correct their writing mistakes
  2. Help them not only learn to pronounce words but also understand them and their surrounding contexts
  3. Assist them in recognising words
  4. Increase their attention span and strengthen their retentive memory
  5. Improve their focus and reading staying power


Statistics show that the global text-to-speech market, valued at USD 2 billion in 2020, is estimated to reach USD 5 billion by 2026. This projected exponential growth only points towards the fact that there’s an increasing global acceptance and adoption of the technology. This is a huge step in the right direction towards providing the world with more literacy, convenience, and accessibility against all odds and social separation.

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