What Is TTS?

What is TTS?

If you’ve ever used Alexa or Siri on your phone to get an answer to a question, then you will have used Text-to Speech conversion technology, maybe without even knowing it. Better known by its acronym TTS, it is a form of speech synthesis that is used to convert written text from a computer or digital device into an audio file. Sometimes also called ‘read aloud’ technology, in just a swipe of a finger on your smartphone or click of a button on your laptop keyboard, TTS will take words that have been written digitally and turn them into audio.

A woman is holding a smartphone on her hand and is about to click something on the screen.
In just a swipe of a finger on your smartphone, TTS will take words that have been written digitally and turn them into audio.

Many other examples of TTS can already be found in applications such as Google Translate, some add-ons and plugins found in web browsers, and GPS systems. It is also used in live-streaming when someone donates money during a live stream and types in a text, which is then turned into a computerised voice that reads the text on the stream in real time.

None of these processes could function without TTS, which reads aloud to you from a predetermined library of words and phrases. You will have likely noticed over the years how AI assistants like Alexa and Siri have started to sound a lot less like the digital robots they actually are. This is because the current goal of many who work with TTS is to make them sound more human by processing the vocal tones of varying ages and genders, so soon users will be able to listen to machine-voiced audiobooks or even communicate with digital assistants without noticing that they’re not talking to a real person.

The Techy Bit

There are many methods of processing TTS. Concatenative TTS, the first method to emerge, uses high-quality audio recordings by voiceover actors that are combined to form speech. Their voices are recorded, labelled and segmented into linguistic units that form huge databases. During speech synthesis, a TTS engine will search these databases for speech units that match the input text and combine them to create an audio file. However, because of the size of the databases, this process can be very time consuming and the resulting audio can sound unnatural.

In scenarios where processing power is limited, Formant Synthesis TTS can produce speech units by generating artificial signals based on a set of rules that have been previously specified. This method can also create output speech that includes a variety of vocal tones and emotions, although it’s difficult to specify timing, so the resulting speech it produces tends to sound robotic.

First introduced in the 1990s and addressing the limitations of the systems mentioned above, Parametric TTS combines parameters like fundamental frequency to generate speech. The text is processed by extracting linguistic features that represent inherent characteristics of human speech. These features are then hand engineered and inputted into a ‘vocoder’ that processes the speech.

Deep Neural Network (DNN) is another variation of TTS that is known as a Deep Learning (DL) technique, where acoustic features are created using models that learn to synthesise speech from text and audio pairs. DL is emerging as the new dominator of the field.

What’s In It For Your Brand?

Although TTS has been a very popular business application where workers have used it to boost productivity in processes like dictation and transcription, it is becoming increasingly more common in ordinary every day usage, including content creators.

TTS is built-in to both Windows and MacOS operating systems. Some word processors can convert text to speech and TTS software — including apps, add-ins, and browser extensions and plug-ins, which can be an extremely helpful options to make information more accessible to those who would otherwise have difficulty learning through more traditional methods — have the ability to provide a multi-sensory reading experience that combines seeing with hearing.

A girl is sitting on the floor and working on her computer that is placed on the coffee table.
With TTS, reading experience becomes more multi-sensory when it combines seeing with hearing.

Using TTS can help those who learn easier by listening, are visually impaired, or have dyslexia, ADHD, autism or any other condition that makes reading text onscreen problematic. Similarly, TTS software can be used by people in the process of learning a new language because it can show them how words are spelled as they are read out, which can make retaining the material much easier and more enjoyable.

TTS software is also helpful where multitasking is needed and the user can listen while their attention is directed in engaging in a physical activity like driving or walking, where reading text would be impractical. For example, if there’s a newspaper article that you want to read, but can’t find the time in your busy schedule to do so, TTS can recite it for you while you’re exercising or cooking, for example. Or they might just prefer listening to reading, and according to experts in the field who follow trends, online contents in audio form are soon rather a rule than exception and more people will be able to enjoy content while on the go.

There are many free TTS software options available, including talking avatars, that give users the ability to ‘read’ any length of text into speech — from individual paragraphs to entire documents. Most of these options work in a similar fashion by allowing users to simply type in the text or upload a text file they want to convert to voice. The next step is to make a selection from the voices available to suit their needs, speed up or slow down the reading speed, change the pitch if necessary, preview the audio until they’re happy, then download the mp3 file once it’s ready.

When it comes to building your brand for the future, one of the biggest benefits of TTS will be improving accessibility to your blog or website, giving your readers the option of reading or listening to your content, which can increase your reader engagement and therefore your ranking. When you embed a TTS option to your website or blog, you’ll automatically improve your reader accessibility, which can also help you grow your subscribers.

So there’s nothing to stop you from using this amazing and evolving technology with your own digital content. What was once technically challenging and expensive is now an ever-developing industry whose affordability is helping voice technology become more efficient for all users.