Speech Synthesis: What It Is & How to Use It | 2025

Key Takeaways:‍

• New technologies are transforming speech synthesis and unlocking new possibilities for communication. 
• Speech synthesis APIs let developers embed these capabilities directly into their products, platforms, and apps. 
• AI video APIs take these advancements further by combining speech synthesis with real-time video generation.
• With Tavus’ APIs, developers can integrate immersive and personalized AI video generation tools into applications. 

New technologies like generative AI are revolutionizing speech synthesis, making voices sound more natural and expressive than ever before. These tools can help simplify the process of creating lifelike voiceovers for virtual assistants, voiceovers, and accessibility. 

But the biggest breakthrough? AI video generation APIs, which let developers embed multisensory, AI-driven video capabilities right into their apps. Tavus API enables easy integration of AI video video generation tools into existing tech stacks. Tavus uses speech synthesis technology to create AI audio that sounds just like a human—and synchronized lip movements to enhance video realism.

This article explains speech synthesis and compares top speech synthesis APIs for a comprehensive look at how some businesses already use this technology to transform communication.

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What is Speech Synthesis?

Speech synthesis is the process of creating clear, natural, human-like speech using advanced technologies and algorithms. 

Although this technology has existed for several decades, recent improvements in text-to-speech (TTS) AI engines have made it more accessible to consumers. As a result, the goal of speech synthesis is also evolving from intelligibility and clarity to naturalness and expressiveness. Today, many of these tools use speech synthesis based on Hidden Markov Models (HHM) and deep learning (DL). 

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How Does Speech Synthesis Work?

Most speech synthesis systems follow a similar series of steps for voice generation:

Text Analysis and Normalization

Once an input is entered, the system starts analyzing it in preparation for speech generation. For TTS applications, the system identifies punctuation, grammar, and context to determine the correct pronunciation and emphatic placement, expands abbreviations, converts numbers into words, and flags highly likely places for mispronunciation. 

For voice cloning applications, this step also involves analyzing audio or video inputs for patterns in pitch, tone, and rhythm to replicate the speaker’s unique style. Tavus API’s best-in-class voice cloning technology utilizes speech synthesis to replicate end users’ voices so every video sounds like it was recorded personally.

Help end users generate high-quality AI videos today. 

Conversion to Phonemes

After the system understands the input, it breaks the words down into phonemes, the smallest sound unit in a language. Following language-specific rules to decide which phonemes to use, the system also considers accents, stress patterns, and silent letters to generate speech that sounds correct and matches the natural pronunciation of words in the intended language or style.

Sound Generation

Finally, the system transforms phonemes into actual speech using one of several methods: concatenative, format, articulatory, or deep learning synthesis. This is also when the system adjusts the tone, pitch, and timing of the speech to make it sound smooth and lifelike. 

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Types of Speech Synthesis Techniques

Speech synthesis typically uses one of four specific techniques:

• Concatenative Synthesis: Stitches together pre-recorded, stored audio snippets of a real human voice, smoothing transitions to sound natural
• Formant Synthesis: Uses mathematical models to produce sounds that simulate the human vocal tract for clear, but often less natural-sounding, results
• Articulatory Synthesis: Uses computer models that simulate and mimic how the human mouth, tongue, and vocal cords work together to make sounds
• Deep Learning-Based Synthesis: Uses AI models trained on large datasets of recorded voices to learn human speaking patterns, predict sounds, and produce convincingly human voices based on text

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Speech Synthesis Use Cases

Multiple use cases for speech synthesis are already transforming how we communicate, learn, and engage with the digital world. 

Assistive Technology

Since its invention in 1968, TTS has revolutionized the assistive technology industry for people with nonverbal communication needs, reading challenges, visual impairments, or learning differences. Also called “read aloud” technology, TTS uses speech synthesis by converting text into audio with the click of a button. 

Today, assistive technology works with nearly every personal digital device, empowering more people to interact with technology and information with fewer barriers.

Voice Assistants and Smart Devices

Voice assistant technology has also been widely available for years. These helpful, familiar characters typically communicate via smart devices like mobile phones, smart speakers, and cars. However, with generative AI giving digital avatars the ability to conduct speech synthesis in real-time, the fundamental nature of virtual assistants—and smart devices—could soon change forever.

Education and eLearning

Speech synthesis tools can also help create training and onboarding content for recruits or customers, educational videos for students, or step-by-step tutorials for products or features. In enterprise settings, for example, where best practices, standards of operations, and policies change frequently, speech synthesis technology makes recording and producing new training videos faster and easier. 

‍Tavus’ Conversational Video Interface allows end users to generate educational or training videos their audiences can interact with in real time. Agents can see and hear to understand input and then respond with less than a second of latency.

Content Creation and Marketing

Speech synthesis can also be a helpful marketing and content-creation tool. With multilingual capabilities, for instance, teams can scale their reach and communicate products and services to customers in multiple languages. But speech synthesis is also a great tool for personalizing interactions—at least 71% of consumers expect personalization from companies today.

‍Tavus API uses speech synthesis to support video generation at scale; with AI video, your end users can create thousands of videos in minutes. No more time-consuming recording processes for marketing or content creation—users create high-quality, realistic content with ease. 

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Best Speech Synthesis APIs 

Let’s take a look at top speech synthesis APIs to help you find the right fit.

1. Tavus API

Tavus provides video APIs for developers to offer end users technology to build hyper-realistic, immersive, customizable AI video experiences directly in their applications. With Tavus’ APIs, developers can empower users to create personalized videos at scale or generate real-time conversational videos.

Although Tavus is not itself a speech synthesis API, it utilizes speech synthesis technology to offer end users highly realistic AI voice cloning.

‍Features:

• Voiceover API: Creates and generates human-like video from text in 30+ languages with TTS capabilities for changing or requesting variables. 
• AI Voice Cloning: Captures and clones users’ voices, speech patterns, tone, and emotion and replicates it in lipsyncing and dubbing. 
• Conversational Video Interface (CVI): Deploys agents that can speak, see, and hear for natural user interactions.
• Lip Syncing & Dubbing APIs: Syncs, dubs, and edits text and script with customization options or dubs your video content in another language.

Pros:

• Uses default TTS or custom audio files to generate videos.
• Implements video generation technology with just a few simple API calls. 
• Blends new techniques to deliver lifelike replicas. 
• Handles safe usage with consent management and content moderation.
• Gives users access to 99+ stock replicas with limitless use cases.

Pricing:

• Starter: $39.00/month
• Growth: $375.00/month
• Enterprise: Custom

Learn how you can implement Tavus into your tech stack today.

2. Murf

Murf.AI is a cloud-based TTS platform for creating voiceovers. Combining augmented machine translation (MT) with human translation, Murf lets users generate audio in 200+ voices across 20+ languages.

Features:

• Text-to-Speech API: Deploys Murf’s voiceovers for apps, websites, and other services.
• Voice Cloning: Generates an AI voice clone that can mimic human emotions. 
• Voices Installer: Integrates Murf’s voices into Windows applications. 

Pros:

• Makes it easy for anyone to create voiceovers
• Allows users to customize accents, tones, and languages
• Saves time and effort for voiceover content creation

Cons:

• High price point
• Limited voice library
• Unnatural-sounding voice fluctuations

Pricing:

• Creator: $29.00/month
• Business $99.00/month
• Enterprise: Custom 

3. Natural Reader

Natural Reader is a text-to-speech platform for creating voiceover audio in commercial, business, and public applications. With products for personal, commercial, and educational applications, Natural Reader supports 20+ document formats with 200+ AI voices in 50+ languages.

Features:

• AI Text-to-Speech: Reads text aloud from 20+ document formats and in 50+ languages.
• AI Text Filter: Filters out unwanted text.
• MP3: Downloads documents to listen offline.
• OCR: Uses a camera scanner to make physical text and books more accessible.

Pros:

• Lets users adjust content easily
• Simplifies audio content creation for everyone
• Generates audio instantly

Cons:

• Integration issues with certain programs
• Restarting the reader can interfere with making corrections

Pricing:

• Personal: $20.90/month
• Commercial: $49.00 or $79.00/month
• EDU: $199.00/yearr or $1.50/user/year

4. WellSaid Labs

WellSaid is a professional TTS AI-generated audio content platform for end-users, developers, teams, and enterprises. Its products use closed AI models trained on licensed voice data for compliant applications.

Features:

• Text-to-Speech API: Helps developers create voice content for digital experiences and platforms using API integrations
• Studio: Lets teams create and collaborate on voiceover projects in real time
• Security: Complies with personal data standards under GDPR  andDSOC2 Type I and Type II certifications
• Integrations: Works with Adobe Premier Pro, Canva, and Adobe Express

Pros:

• Creates content with human-sounding voices.
• Produces audio quickly with the ability to make instant changes.
• Protects data with trusted and secure AI voices.

Cons:

• High prices with limited customization options
• Poor customer service reported by some users
• Issues with AI voices, especially pronunciation and pitch

Pricing:

• Maker: $49.00/month
• Creative: $99.00/month
• Team: $199.00/month
• Enterprise: Custom 

5. Amazon Polly

Amazon Polly is a fully-managed voice generation service from Amazon that converts text to audio. It uses DL technologies to provide dozens of voices in multiple languages for building speech-activated applications. 

Features:

• Amazon Polly API: Integrates speech synthesis into applications
• Voices and Languages: Includes dozens of voices and support for a variety of languages with Standard and Neural TTS (NTTS) voices and Long-Form and Generative voices
• SSML Customization: Supports SSML (Speech Synthesis Markup Language) and common SSML tags

Pros:

• Adds speech to applications such as RSS feeds, websites, or videos
• Stores and replays speech outputs to prompt callers through interactive or automated voice response systems
• Creates voiceovers for media directly from scripts with SSML-based customization options

Cons:

• Some G2 users mention that Amazon Polly works best when integrated with AWS
• Limited voice and language options, as well as concerns about high pricing

Pricing:

• Standard Voices: $4 per 1 million characters
• Neural Voices: $16 per 1 million characters
• Long-Form Voice: $100 per 1 million characters
• Generative Voices: $30 per 1 million characters

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Future Trends in Speech Synthesis

Speech synthesis is on the brink of transformation, driven by next-gen AI technologies. Innovations like AI video APIs, which combine natural-sounding speech with real-time video generation, are opening new doors for personalized, immersive AI video experiences across industries. 

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Learn More About Speech Synthesis

Answers to common speech synthesis questions.

What is the difference between synthetic speech and speech synthesis?

Synthetic speech is the artificially generated voice you hear, while speech synthesis is the actual process behind creating that voice. In other words, speech synthesis is the technology that powers synthetic speech. 

What are the stages of speech synthesis?

Speech synthesis typically involves three main stages:

1. Text analysis and normalization, where the system processes input text and prepares it for speech generation
2. Phoneme conversion, where the system breaks text into phonemes for accurate pronunciation
3. Sound generation, where the system transforms phonemes into audible speech

What is the best speech synthesis software?

The best speech synthesis software depends on your needs. However, for businesses looking to integrate AI video capabilities into products, platforms, or applications, Tavus’s APIs are the best option.

Tavus stands out as a premier AI-powered speech synthesis and video generation platform, specifically designed for developers whose end users need to create personalized and scalable video content at scale. Unlike traditional text-to-speech solutions, Tavus takes their offerings a step further by enabling hyper-realistic AI-generated videos with customizable speech synthesis. This allows end users to produce dynamic, engaging content without requiring manual recording for each variation.

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Harness the Power of Speech Synthesis in Your Technology

Don’t get left behind as speech synthesis enters its next phase of innovation. With advancements in AI, this technology is no longer limited to voiceovers or TTS—it’s powering personalized videos and immersive customer experiences at scale. 

Leading this transformation is Tavus. By providing developers with cutting-edge tools to embed AI video generation and conversational video interfaces into their applications, Tavus makes it easy to create impactful content with just a few API calls, whether your users are building personalized marketing campaigns, training modules, or interactive user experiences. 

‍Take speech synthesis to the next level today with Tavus.