The Internet of Speech is here, transforming the way we interact with our devices.
Siri notifies you of your next shift in an unfamiliar city. Google Assistant searches the web for instructions on how to grill salmon and reads them to you as you work. The voice robot on the other end of the customer service line delivers results, without waiting for menus or pressing a button. Call it the era of conversational computing, andThe computer end of these conversations comes courtesy of a digital technology called Text-to-Speech, or TTS for short.
But TTS is not just for new and sophisticated voice computing applications. It has been used as an accessibility tool for years; as educational technology (edtech); and as an audio alternative to reading. In 2021 almost oneamerican adults bedroomI listened to audiobooks and TTS may have helped make these experiences possible. All these examples just scratch the surface of what TTS can do.
In this article, we describe the standard meaning of text-to-speech and list some of the demographics that benefit from TTS. Next, we look at some of the ways organizations can use language technology to achieve mission-critical objectives. Finally, we'll take you through the history of this ever-evolving field. Here's your definitive introduction to TTS technology, starting with a basic question:
What is TTS? In other words, what does TTS mean?
Curious to know what today's leading TTS actually sounds like?Discover ReadSpeaker's TTS voices, complete with audio examples.
Text to Speech: meaning and science behind the term
Text-to-speech technology is software that takes text as input and produces audible speech as output. In other words, it's text-to-speech, which makes TTS one of the most highly regarded technologies of the digital revolution. A TTS system includes software that predicts the best possible pronunciation of a given text. It also includes the program that creates voice sound waves; this is calledvoice embarrassment
Text-to-speech is a multidisciplinary field that requires in-depth knowledge of a variety of sciences. If you wanted to build a TTS system from scratch, you would need to study the following topics:
- Linguistics, the scientific study of language.To synthesize coherent speech, TTS systems need a way to recognize how written speech is pronounced by a human speaker. This requires knowledge of linguistics down to the level of the phoneme: the sound units that collectively make up language, like the /c/ sound in gato. To achieve a truly realistic TTS, the system must also predict proper prosody, which includes speech elements beyond the phoneme, such as stress, pauses, and intonation.
- Processing audio signals, creating and editing digital sound representations.Audio (voice) signals are electronic representations of sound waves. The voice signal is digitally represented as a sequence of numbers. In the context of TTS, linguists use different representations of functions that describe discrete aspects of the speech signal, allowing AI models to be trained to generate new speech.
- Artificial intelligence, specifically deep learning, a type of machine learning that uses a computer architecture called a deep neural network (DNN).A neural network is a computational model inspired by the human brain. It consists of complex networks of processors, each of which performs a processing task before sending its output to another processor. A trained DNN will learn the best processing route to get accurate results. This model offers great computational power, making it ideal for handling the large number of variables required for high-quality speech synthesis.
ReadSpeaker linguists conduct research and practice in all these areas and continually improve TTS technology. These researchers produce lifelike TTS voices for brands and developers that enable companies to differentiate themselves through the Internet of speech, whether on a smartphone, smart speakers or a voice-enabled mobile app. In fact, TTS voices are emerging on an ever-increasing range of devices and for an ever-increasing number of applications (and users).
Who uses TTS?
People with visual and reading disabilities were early adopters of the TTS. It Makes Sense: TTS Makes the Internet Experience Easier for People1 in 5 people with dyslexia.It also helps low-literate readers and people with learning difficulties by taking the stress out of reading and presenting information in an optimal format. We are moving towards a more accessible Internet of the future and TTS is an integral part of that movement.
Many forward-thinking publishers and content owners are already offering TTS solutions to make the web a place for everyone. Companies and buildings must facilitate access for wheelchair users and people with reduced mobility. Shouldn't the Internet be accessible to everyone? However, as technology has evolved, so have the uses and users of TTS. You may not need TTS, but you certainly will. Text-to-speech can make life easier and more efficient no matter how you define it.
These are just some of the populations already benefiting from TTS technology:
1. Students
real studiessuggest that students benefit more from blended presentations. Some students retain more information presented in audio and visual formats, also known asBimodal learning.A popular educational framework calledUniversal Design for Learning (UDL)recommends dual modal learning to help all students succeed. Teachers in all grades who promote UDL use a combination of auditory, visual, and kinesthetic techniques with the help of technology and customizable lesson plans.
Even if you identify as a kinesthetic or visual learner, science says that adding an auditory method can help you retain information. Last but not least, TTS makes proofreading much easier.
2. Anywhere reader
If you want to keep up with the news, podcasts and audiobooks will only take you so far. So if there is a detailed profilethe new yorkeror a long articleThe guardwant to read, TTS can recite it for you. So you can drive, exercise or clean at the same time. Or maybe you just prefer listening to reading. Correspondingleading technology expertsOnline content will soon be automatically converted to audio so more people can enjoy content on the go.
3. Multitasking
The shortcuts TTS can provide are endless, from reading recipes while cooking to dictating instruction manuals while assembling furniture. The only limit to how much you can help is your own imagination.
4. Mature Readers
Older adults understandably want to avoid straining their eyes to read tiny text on a smartphone. Text-to-speech can alleviate this problem by making online content easy to consume, regardless of your technology skills or vision.
5. Younger generations
Give young people technology and they are likely to use it, whether it's strictly "necessary" for them or not. 2022,70%of 18- to 25-year-olds turned on closed captions "most of the time" while watching video content, not because they were hard of hearing, but because it was convenient. And many Tik Tok users took advantage of the app's TTS feature, which rivals Instagram.presented its TTS in 2021.meanwhile acollege graduation researchfound that only 5% of respondents had a disability that required the use of assistive technology, yet at least 18% of students considered any technology 'necessary'. The thing is, Gen Z uses TTS not just as an accessibility tool, but as a preference.
6. Readers with visual impairment or photosensitivity
Older adults aren't the only ones who want to avoid squinting at screens. Many people have mild visual impairments or are sensitive to light. For example, think of people with chronic migraines. Thanks to TTS, these users can be more productive on days when looking at screens seems overwhelming.
Really,Advice on medical studies.that exposure to light at night, particularly blue light from computer screens, has adverse health effects. Not only does it mess with biological clocks, but it can also increase your risk of cancer, diabetes, heart disease and obesity. Text-to-speech offers users a safer way to consume written content without looking at the screen.
7. Foreign language student
Studies show that listening to another language helps students learn the new dialect. Text to speech can help with this.ReadSpeakeris an international TTS software company with 50+ languages and 150+ voices, all based on native speakers.
With ReadSpeaker, foreign language learners can familiarize themselves with pronunciation, cadence and accents. A particularly useful feature in this regard is the ability to highlight words as you read them, which can help students feel confident pronouncing new vocabulary.
8. Multilingual readers
New generations growing up in multilingual homes may understand the language of their parents (grandparents), but may not feel fluent enough to read, write or speak it. This is common in many communities where the mother tongue is not taught in schools. For second and third generations who want to maintain or strengthen their ties to their home countries, ReadSpeaker can make articles, journals, and other literature accessible and understandable through language.
9. People with severe speech impediments
A speech generation device (SGD), also known as a Voice-Over Communication Aid (VOCA), is useful for those who have severe speech problems and are unable to communicate verbally. Summarized under the term "Augmentative and Alternative Communication (AAC)", SGD and VOCA can now be integrated into mobile devices such as smartphones.
Stephen Hawking, who suffered from ALS, and renowned film critic Roger Ebert were among the most well-known users of SGD with TTS technology. So who uses TTS? Many people, for many different reasons. And if you're looking for a way to solve today's business challenges, TTS might be the technology for you.
For more information about ReadSpeaker's TTS services, visit theirproductsoFREQUENTLY ASKED QUESTIONS.
TTS technology for enterprises
When ReadSpeaker AI started with speech synthesis in 1999, TTS was primarily used as an accessibility tool. Text-to-Speech makes written content available across all platforms for people with visual impairments, low literacy, cognitive impairments, and other accessibility barriers. And while accessibility remains a core value ofReadSpeaker solutions,The rise of voice computing has given rise to a growing range of applications for TTS across all devices, especially the enterprise.
Here are just a few of the powerful business use cases for TTS in today's voice world:
- Conversational Interactive Voice Response (IVR) System,as in customer service call centers
- voice trading applicationshow to shop on an amazon alexa device
- voice guidance and navigation tools,Wie GPS-Mapping-Apps
- smart home devicesand other voice-enabled Internet of Things (IoT) tools
- Autonomous Virtual Assistantslike Apple's Siri but for its own brand
- Experimental Marketing and Advertising Solutions,such as interactive voice announcements on music streaming services or branded smart speaker apps
- video game development,with dynamic TTS runtime for accessibility features, scene prototyping and AI non-player characters
- Corporate training and marketing videosthat allow creators to alter voiceovers without tracking original voice talent for ongoing recording sessions
Chances are you've already experienced TTS through some or all of these examples. If you run a business, you may have even helped create a voice-first device or experience. Given this wide usage, it's safe to say that TTS is here to stay. But it's not exactly a new technology.
Types of TTS technology, then and now
Mechanical attempts at synthetic speech date back to the 18th century. Electric synthetic speech has been around sinceVoder, by Homer Dudley, 1930s.But the first system that went directly from text to speech in Englisharrived in 1968,and was designed by Noriko Umeda and a team at the Japan Electrotechnical Laboratory.
Since then, researchers have developed a number of new TTS technologies, each of which works in its own unique way. You might be wondering, "How does text-to-speech work?" The answer depends on the TTS technology you are using. Here's a brief overview of the dominant forms of TTS, past and present, from early experiments to the latest AI features.
Formant synthesis and articulatory synthesis
Early TTS systems used rule-based technologies such as formant synthesis and articulatory synthesis, which achieved a similar result through slightly different strategies. Pioneering researchers recorded a speaker and extracted the acoustic characteristics of that recorded speech: formants that define the qualities of speech sounds in formant synthesis and the type of articulation (nasal, plosive, vowel, etc.) in synthesis. They would then program rules that would replicate those parameters with a digital audio signal. This TTS was quite robotic; These approaches inevitably abstract much of the variation you find in human speech, things like variation in pitch and stress, because they only allow programmers to write rules for a few parameters at a time. But formant synthesis is not just a historical novelty: it is still used in the open source TTS synthesizer.Ehablar OF,the language to synthesizeNVDA,one of the top free screen readers for Windows.
diphone synthesis
The next major development in TTS technology is called diphoneme synthesis, which was pioneered by researchers in the 1970s and was still widely used at the turn of the millennium. Diphone synthesis creates machine speech by mixing diphones, combinations of individual phonemes, and the transitions from one phoneme to the next: not just the /c/ in the word cat, but the /c/ plus half of the next sound /ae/. Researchers record between 3,000 and 5,000 individual diphones, which the system combines into a coherent statement.
TTS technology for diphone synthesis also includes software models that predict the duration and pitch of each diphone for given input. When these two systems overlap, the system combines the crosstalk signals and then processes the signal to correct pitch and duration. The end result is more natural sounding synthetic speech than formant synthesis produces, but it is far from perfect, and listeners can easily distinguish a human speaker from this synthetic speech.
unit selection overview
In the 1990s, a new form of TTS technology took hold: the steering selection synthesis, which is still ideal today for TTS engines with reduced dimensions. Where diphone synthesis has added the appropriate duration and pitch through a second processing system, unit selection synthesis skips this step: it starts with a large database of recorded speech (about 20 hours or more) and selects the sound fragments that already have the duration and pitch. text input required for natural sounding speech.
Unit selection synthesis produces a human-like language without much sign modification, but is still artificially identifiable. During all these decades of development, the processing power of computers and available data storage made rapid advances. The stage was set for the next era of TTS technology which, like so much else in today's computer age, relies on artificial intelligence to deliver incredible predictive power.
neural synthesis
Remember the deep neural networks we mentioned earlier? This is the technology that is driving today's advances in TTS technology and is the key to the realistic results that are now possible. Neural TTS, like its predecessors, starts with voice recordings. This is an entry. The other is text, the written script that the source speaker used to create these recordings. Feed these inputs into a deep neural network and learn the best possible mapping between a piece of text and its associated acoustic features.
Once trained, the model will be able to predict a realistic sound for new texts: with a trained TTS neural model, together with a vocoder trained with the same data, the system can produce a voice similar to the source speaker. remarkably similar when exposed to virtually any new text. This similarity between source and output is why neural TTS is sometimes referred to as "Voice Cloning.”
There are all sorts of signal processing tricks you can use to alter the resulting synthesized voice so that it doesn't sound exactly like the source speaker. The most important fact to remember is that the best AI-generated TTS voices still start with a human speaker, and TTS technology is becoming more and more human. Current research is leading to TTS voices that speak with emotional expression, unique voices in multiple languages, and increasingly realistic audio quality.Discover available languages and voices with ReadSpeaker TTS.
It's probably more technical information than you need, but it covers the basics of text-to-speech and more. And if you still have questions, follow the links below.
For more information on text-to-speech, see Help for creating your ownbrand voice,ready market accessvoces TTSin more than 30 languages,Contact ReadSpeaker today.