Speech to Speech
Any voice, any accent, anytime
Convert any recorded voice into any other voice in seconds. Synthesys speech-to-speech preserves the timing, emotion, and intonation of your source audio, then re-synthesises that performance through the target voice you choose.
Used across marketing, podcasting, e-learning, and accessibility teams to turn one recorded performance into every voice they need — in 140+ languages, without re-booking talent.
Empower Your Voice With Synthesys Speech-to-Speech AI: Any Voice, Any Accent, Anytime
Instantly transform your voice into another voice or accent. Achieve a natural-sounding voice in under five minutes with Synthesys speech-to-speech AI.
Trusted by global enterprise teams
What is speech-to-speech AI?
Speech-to-speech AI is voice conversion technology that takes an existing audio recording and re-voices it through a different speaker, while preserving the timing, prosody, emotion, and intonation of the original performance. Unlike text-to-speech, which generates audio from written text, speech-to-speech starts from your existing recording. The output sounds like the target speaker delivered the line themselves, with the source actor's timing intact.
Synthesys speech-to-speech sits inside a wider voice production studio that also handles voice cloning, AI dubbing, and AI avatar video. That means one source recording can become a localised voiceover, a multi-language ad campaign, or a lip-synced avatar video without leaving the dashboard.
Unlock your passport to sound exactly like anyone with Synthesys speech-to-speech AI
What do you do when the voice you have selected doesn't sound exactly as you want? Do you keep regenerating different voices? This would be exhausting. With Synthesys speech-to-speech AI, however, you can use the exact voice you want when you want. You can use your own voice or choose one of our natural-sounding voices. Morph your voice into any accent in six clicks, and share your message with the world.
Preserve emotion and timing
Breath, pauses, emphasis, and pitch contours from your source recording carry into the output voice. The new speaker delivers the line with the same intent.
Any target voice in seconds
Pick from the studio library, or convert through a voice you have cloned yourself. Same source clip, different speaker per render. Iterate without re-recording.
140+ languages, one recording
Retarget your source delivery to native voices in over 140 languages. Localise an entire campaign without re-booking voice talent per market.
Speech-to-Speech vs Voice Cloning vs Text-to-Speech
Three related voice technologies inside Synthesys AI Studio. Each solves a different production problem. Pick by starting input.
| Property | Speech-to-Speech | Voice Cloning | Text-to-Speech |
|---|---|---|---|
| Starts from | Existing audio recording | 10-second voice sample | Written text |
| Preserves source timing and emotion | Yes | No (generates fresh delivery) | No (generates fresh delivery) |
| Changes the speaker | Yes, to any target voice | Captures one new voice | Reads in chosen library voice |
| Best for | Re-voicing existing takes, ADR, localisation | Building a reusable brand voice | Generating voiceover from scripts |
| Multilingual | 140+ languages | 140+ languages | 140+ languages |
| Typical use case | Podcast pickups, dubbing, accessibility | Founder voice for marketing | Course narration, explainer videos |
Most teams use the three together. Clone a brand voice once, then run every new recorded take through speech-to-speech into that cloned voice. Use text-to-speech for fresh scripts where there is no source recording to convert.
Why Use Synthesys Studio's AI Speech-to-Speech Generator?
Four reasons teams choose Synthesys speech-to-speech over standalone voice tools.
Versatility
Change your voice into any accent with our 14+ premium voices, catering to diverse communication needs.
Customisation
Tailor your message precisely using advanced voice modulation controls and fine-tune settings, ensuring clarity, authenticity, and resonance with your audience.
Accessibility
Empower users with speech disabilities, such as cerebral palsy or muscular dystrophy, to communicate effectively through natural voice generation.
Efficiency
Enjoy fast rendering times, unlimited audio renders, and an intuitive user interface, maximising productivity, user engagement, and global reach in various applications like content creation, public announcements, or professional services.
Synthesys AI Voices Speech to Speech
A sample of the speech-to-speech target voices most teams reach for first. The wider library covers 400+ voices across 140+ languages, plus any voice you clone yourself.
Rachel
Warm narration voice, calibrated for podcast hosts, audiobook ADR, and explainer voiceover.
Domi
Confident, mid-tempo delivery suited to product ads, brand promos, and creator UGC content.
Drew
Authoritative male voice for training narration, financial content, and corporate explainer.
Clyde
Deep British voice for documentary narration, premium brand storytelling, and audiobook fiction.
Alice
Polished British female voice for e-learning narration, corporate training, and audiobook reads.
How To Use Synthesys Studio's AI Speech-to-Speech Generator
Ready to transform your voice? Follow these four steps.
Begin Your Project
Log into your Synthesys account and initiate your project by clicking on the "AI Voices" button.
Upload your audio sample
Upload your voice recording or simply speak directly into the platform. Synthesys automatically understands your speech and converts it to your desired accent. We recommend that you upload MP3 files for best results.
Choose your voice
Choose the perfect voice to match your target audience.
Save and download
Save your audio project and download it in MP3 format for easy sharing and use across various platforms.
Speech-to-Speech Use Cases by Industry
Six common workflows where speech-to-speech replaces a re-recording session, a second studio booking, or a multilingual voice cast.
One English ad read needs Spanish, French, German, and Japanese versions for a campaign launch on Friday.
Run speech-to-speech on the source recording against native voices in each language. Ship four localised audio tracks the same day, with the original delivery intact.
A flubbed line in an episode that already aired everywhere except the sponsor read at minute 14.
Re-record the corrected line, retarget it through your cloned host voice using speech-to-speech, drop the new clip into the timeline. The fix is invisible.
Course modules recorded by an in-house SME who is no longer available, but updates are needed for a compliance refresh.
Record the new sections in any voice. Retarget through the SME's previously cloned voice (with their consent). The refreshed course keeps the original speaker identity.
A small cast of voice actors needs to cover 40 distinct character voices for a launch trailer.
Direct one actor to deliver every line with the right emotional shape. Retarget each line through a different target voice in the library. Forty characters from one performance session.
A founder living with vocal fold paralysis wants to record weekly company-wide video updates.
The founder records at their natural pace. Speech-to-speech retargets the audio through a clearer voice while preserving every word, every pause, every emotional inflection.
ADR for a chapter where the original narrator is unavailable, but listener expectations require voice continuity.
Record the corrected passage with any reader. Retarget through the narrator's cloned voice with speech-to-speech. The chapter ships without a re-booking.
Speech-to-Speech supported languages
Voice cloning consent, watermarking, and commercial license
The four principles that govern how Synthesys speech-to-speech handles voices, recordings, and rights.
Consent first
You must hold explicit consent for any voice you upload, retarget, or clone. That covers your own voice, talent licensed with signed release forms, voice artists with written permission, or voices in the public domain. Synthesys terms of service prohibit non-consensual voice cloning, impersonation, and fraud. Accounts found in violation are terminated and content is removed.
Secure handling
Source recordings are encrypted in transit and processed in isolated render environments. Synthesys AI Studio never uses your source audio to train public models. Source files are removed from servers per the published privacy policy. Agencies and enterprise teams can request dedicated workspaces with additional retention controls.
Commercial rights from $29
Every Synthesys plan, including Indie, ships with full commercial rights on speech-to-speech outputs. No royalties, no attribution requirements, no per-output licensing fee, no platform restrictions. Use the converted audio in paid ads, broadcast, streaming, client deliverables, and product launches. The licence is perpetual.
Compliance cooperation
Synthesys cooperates with platform takedown requests and with law enforcement when required. Reports of unauthorised use go to support@synthesys.io. Brand-safe, rights-respecting voice work is the only kind worth scaling — and the product surface enforces that, not just the policy page.
Read the full ethics policy, terms of service, and privacy policy. Report concerns to support@synthesys.io.
What Teams Are Saying
"Their AI models are incredibly advanced — so realistic it's almost impossible to tell they're AI-generated. The quality has consistently improved."
Dr Yara Loua
Healthcare Professional · Verified Trustpilot Review
"I rely heavily on Synthesys to help me stay ahead with marketing across my three businesses. It handles everything I used to outsource."
Randy Cole
Business Owner · Verified Trustpilot Review
"My clients can't tell they're not real people — the lip-sync is spot on. It's become a core part of how we deliver client presentations."
Jexter N
Agency Professional · Verified Trustpilot Review
"The AI-powered features are game-changers — the auto-generated scripts and voiceovers save me so much time."
Michael Mubi
Marketing Manager · Verified Trustpilot Review
"I can clone myself and my voice, then easily create a lot of short clips without re-filming or redoing anything. Massive time saver."
Thomas
Content Creator · Verified Trustpilot Review
"Created a welcome video and 3 course videos in one sitting. The software made the whole process flawless — I'm hooked."
Bonnie Williams
Course Creator · Verified Trustpilot Review
"My avatar can easily translate my message into many other languages. It does a great job reaching audiences I couldn't before."
Joseph Wood
International Marketer · Verified Trustpilot Review
"The AI voice generator is great for creating videos at work. Their AI image and video editors make everything seem more professional and polished!"
Bruna Duarte
E-commerce Brand Owner · Verified Trustpilot Review
Have questions? We have answers.
Find everything you need to know about getting started, managing your account, and creating professional AI videos.
What is speech-to-speech AI and how does it differ from text-to-speech?
Speech-to-speech converts an existing audio recording into the voice of a different speaker while keeping the original timing, pacing, emotion, and intonation intact. Text-to-speech starts from written text and reads it aloud in a chosen voice. The difference matters in practice: if you record a take with the right emotional delivery but the wrong voice, speech-to-speech preserves the performance and only changes the speaker identity. Synthesys speech-to-speech reads pitch contours, breath patterns, micro-pauses, and stress placement from your input audio, then re-synthesises that performance through a chosen voice. The output sounds like the new speaker delivered the line themselves, with the original actor's timing.
How does Synthesys Studio revolutionise communication strategies?
By collapsing the gap between idea and finished voiceover. Teams that previously coordinated voice talent bookings, studio sessions, and post-production rounds now ship the same audio in one sitting. Record a guide track in your own voice, run speech-to-speech to retarget it to a brand voice, and publish. Multilingual campaigns use the same loop: one recorded delivery, retargeted across markets without re-booking voice artists per language. The communication strategy shift is from sequential, gated production to parallel, iteration-first production. Synthesys speech-to-speech is the lever that makes that shift practical for marketing teams, e-learning departments, podcasters, and product teams alike.
What industries can benefit from Synthesys Studio's AI speech-to-speech capabilities?
Most industries that touch audio production. Marketing teams retarget winning ad reads across multiple brand voices to test which delivery converts. E-learning and corporate training departments build multilingual course libraries by recording once and retargeting across languages and presenter voices. Podcasters use it to fix flubbed takes without re-recording. Game developers and animation studios deliver large casts of distinct character voices from a small pool of recorded actors. Audiobook publishers handle ADR (automated dialogue replacement) without booking the original narrator. Accessibility teams give a clearer, more consistent voice to speakers with vocal fatigue or speech disabilities. Localisation studios accelerate dubbing pipelines. Each industry uses the same underlying capability: change the speaker, keep the performance.
How does Synthesys Studio guarantee authentic and precise speech output?
Output authenticity comes from three layers. The voice models are trained on studio-grade recordings rather than scraped or noisy data, so each voice carries a consistent timbre across long passages. The conversion pipeline preserves prosody from your input recording, so emphasis, pauses, and emotional shape carry through to the output. And every render is processed through a quality stage that smooths transitions between phonemes and removes the artifacts that betray earlier-generation voice AI. The result is speech-to-speech output that holds up under headphone listening, broadcast distribution, and side-by-side comparison with the source recording.
In what ways does Synthesys Studio support users with speech disabilities?
Speech-to-speech is one of the most practical accessibility tools in the Synthesys catalogue. A speaker living with dysarthria, vocal fold paralysis, or post-laryngectomy speech can record dialogue at their natural pace and have the AI retarget it to a clearer voice while preserving every word, every pause, every emotional inflection. The output reads as the same speaker, communicating with the same intent, in a voice that listeners parse more easily. The same workflow helps speakers with vocal fatigue, those recovering from voice surgery, or anyone whose recorded voice differs from how they want to be heard professionally. Voice ownership and identity stay with the speaker. Only the acoustic delivery changes.
Is speech-to-speech the same as voice cloning?
No, but they share infrastructure. Voice cloning captures a person's vocal identity from a short sample, then lets you generate new speech in that voice from text. Speech-to-speech takes an existing audio recording and re-voices it through a chosen target voice. Voice cloning answers "what would this person sound like reading new text". Speech-to-speech answers "what would this exact performance sound like in a different voice". Synthesys offers both inside the same studio. Many teams use them together: clone a brand voice once, then use speech-to-speech to retarget every new ad read to that cloned voice while keeping the original creative direction in the source recording.
Can I use speech-to-speech for multilingual voiceovers and dubbing?
Yes. The Synthesys speech-to-speech engine pairs with the wider voice library to support over 140 languages and accents. Workflow: upload a source recording in any language, choose a target voice in the language you need, and the system produces an output that carries the source's timing and emotion into the target language. For full video dubbing with lip-sync, route the output through Synthesys AI Dubbing. For audio-only multilingual campaigns, podcast episodes, or audiobook chapters, speech-to-speech alone is enough. The same recorded performance can ship across US English, UK English, Spanish, French, German, Japanese, Mandarin, Arabic, and dozens more without separate recording sessions per market.
How long can the input audio be?
Most users run speech-to-speech on clips between 5 seconds and 10 minutes per render. For longer formats such as full audiobook chapters, training modules, or podcast episodes, split the source into segments and process them in parallel, then stitch the outputs together. Total monthly throughput scales with your plan. Indie covers regular content production. Studio handles agency or e-learning volume. Agency is built for teams running localisation and dubbing at scale. There is no per-minute surcharge inside the included quota, so retargeting a 30-minute episode costs the same in credits whether you process it as one render or six.
What audio formats are supported for input and output?
Input accepts WAV, MP3, M4A, FLAC, and OGG, with no separate transcoding step required. Output is delivered as high-bitrate MP3 by default with WAV available on Studio and Agency plans for downstream production work. Bit depth, sample rate, and noise floor on the output are calibrated for direct upload to streaming, ad platforms, and broadcast pipelines. For producers working in Pro Tools, Logic, Adobe Audition, or DaVinci Resolve, the WAV output drops in cleanly without conversion. For social-first creators, the MP3 default ships straight to TikTok, YouTube Shorts, Instagram, or podcast hosts.
Does the speech-to-speech output sound robotic or natural?
Natural enough that most listeners cannot tell it was processed. The model preserves breath, hesitation, and the small imperfections that signal a real speaker, then renders them through the chosen target voice. The common giveaways of older voice AI, such as flat affect, uniform pacing, and over-clean phoneme transitions, are not present. For applications where naturalness matters most, such as audiobook narration, podcast hosts, and brand spokesperson reads, the output sits inside the band of quality that listeners associate with professionally recorded studio audio.
Can I use Synthesys speech-to-speech commercially?
Yes. Every Synthesys plan, including Indie, includes full commercial rights on speech-to-speech outputs. Use the audio in paid ads on Meta, TikTok, YouTube, and any other platform. Publish on podcast hosts, embed in product videos, ship inside training courses, deliver to clients as an agency, or distribute through broadcast and streaming. No royalties, no attribution required, no per-output licensing fee, no platform restrictions. The licence is perpetual. Audio you generate today is yours to use and distribute indefinitely. Agencies producing voiceovers for clients can deliver the output as a final asset without any additional licensing conversation.
What about consent and ethics when cloning or retargeting a voice?
You must hold explicit consent for any voice you upload, retarget, or clone. That covers your own voice, talent you have licensed with signed release forms, voice artists who have given written permission, or voices in the public domain. By uploading, you confirm to Synthesys that you hold those rights. Synthesys terms of service prohibit non-consensual voice cloning, impersonation, fraud, defamation, and audio that violates someone's publicity or privacy rights. Accounts found in violation are terminated and content is removed. Synthesys cooperates with platform takedown requests and law enforcement where applicable. Reports of unauthorised use go to support@synthesys.io. The technology is legal. Responsibility for the source material is yours.
How does Synthesys speech-to-speech compare with ElevenLabs, Murf, and Resemble?
Each platform has a different centre of gravity. ElevenLabs is voice-first with strong cloning and a developer-heavy ecosystem. Murf is text-to-speech-led with a polished studio editor. Resemble focuses on real-time and enterprise voice infrastructure. Synthesys speech-to-speech sits inside a broader AI video and voice studio: the same workspace that retargets your audio also handles AI dubbing, AI avatar video, face swap (Recast), product video, UGC ad generation, and full multi-model video orchestration. Teams who already produce video content gain more leverage from a single subscription that covers voice and video together, rather than stitching multiple specialised tools and licences. Pricing starts at $29 per month with commercial rights on every plan.
How do I start using Synthesys speech-to-speech?
Sign in at app.synthesys.live and open the AI Voices workspace. Select the Speech2Speech tab. Upload your source audio (WAV, MP3, M4A, FLAC, or OGG), choose a target voice from the library or your own cloned voices, and click generate. The first render typically completes in under a minute for short clips. From there, iterate: try different target voices on the same source, fine-tune emphasis, or chain the output into AI Dubbing for multilingual lip-synced video. Full commercial rights apply on every paid plan from the first export.
Speech-to-Speech Glossary
The four terms most often confused in voice AI conversations. Direct definitions, no jargon.
- Speech-to-speech (S2S)
- Voice conversion AI that re-voices an existing audio recording through a different target speaker while preserving the source timing, prosody, and emotion. Distinct from text-to-speech, which generates audio from written text.
- Voice conversion
- The acoustic transformation that changes the perceived speaker identity of an audio signal while keeping its linguistic content and performance intact. Voice conversion is the underlying mechanism behind speech-to-speech.
- Voice cloning
- Capturing a target speaker's vocal identity from a short audio sample, typically 10 seconds, to enable generation of new speech in that voice. Voice cloning produces the target voice model used by speech-to-speech and text-to-speech engines.
- Speaker embedding
- A compact numerical representation of a speaker's vocal identity, learned from training audio. Speech-to-speech engines disentangle speaker embedding from linguistic and prosodic content so the speaker can be swapped without altering the performance.