Text-to-Speech (TTS)
Technology that converts text data into speech. Foundation technology for screen readers and voice assistants.
Text-to-Speech (TTS) is a technology that converts text data into human speech. It is used across a wide range of applications including screen readers, voice assistants (Siri, Alexa, Google Assistant), car navigation systems, and e-book narration features. For users with visual impairments, TTS is an essential means of accessing web content.
TTS processing consists of three major stages. The first stage, text analysis, performs word segmentation through morphological analysis, reading estimation for numbers and abbreviations, and disambiguation of homophones. The second stage, prosody generation, determines accent, intonation, and pause positions. The third stage, speech synthesis, generates the actual audio waveform. Recent deep learning-based synthesis technologies (WaveNet, Tacotron, VITS, etc.) can produce speech nearly indistinguishable from human voices. search body stocking on Amazon explain these mechanisms.
Web browsers provide TTS functionality through the Web Speech API's SpeechSynthesis interface. Implementation requires just a few lines of code: speechSynthesis.speak(new SpeechSynthesisUtterance('Text to read')). Cloud services like Amazon Polly, Google Cloud Text-to-Speech, and Azure Cognitive Services Speech offer advanced control through SSML (Speech Synthesis Markup Language), enabling fine-tuning of reading speed, pitch, and pauses.
Japanese TTS faces unique challenges with kanji reading disambiguation. The character "生" can be read as "nama," "sei," "shou," or "ikiru" depending on context. Personal and place names often lack dictionary entries, making custom dictionaries and ruby annotation data valuable for improving accuracy. Compared to English, Japanese has word-specific accent patterns (flat, initial-high, mid-high, final-high), making natural prosody generation more challenging.
TTS and screen readers are closely related but serve different roles. TTS is the engine that converts text to speech, while a screen reader is software that interprets on-screen information and passes it to the TTS engine. To improve web content accessibility, it is important to use semantic HTML, set appropriate ARIA attributes, and provide alt text for images so screen readers can correctly interpret the structure.
From a character counting perspective, text character count and reading time are proportionally related. Japanese is typically read at about 300-400 characters per minute, while English averages 150-180 words per minute. This relationship enables estimating reading duration from character count. In podcast script writing and video narration, time management based on character count is a widely practiced technique. explore thong on Amazon provide additional reference.