ElevenLabs vs OpenAI Speech to Text
Learn about the differences between ElevenLabs and OpenAI TTS in voice AI models.
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Compare ElevenLabs and OpenAI TTS
OpenAI TTS offers natural intonation and high fidelity but has limited voice options. Eleven Labs provides more voice customization and emotional range, though with occasional synthetic artifacts.
Updated at:
Feb 14, 2025
Features
ElevenLabs
Typically around 300 ms + network time
Natural and realistic, widely used by all types of content creators
Limited to 40k characters per request
Requires 30 seconds of audio
IPA Support, isolated pronunciation
Stability, similarity, and style exaggeration controls
8kHz audio, telephony optimized voices
No on-device generation available
15 languages with extensive dialect coverage
2-15 depending on the plan
OpenAI Speech to Text
200 ms + network time, slower response times
Lower quality ratings in human evaluations, and limited emotional control
Limited character count for longer texts
Requires 15 seconds of audio
Requires 60 minutes of audio
Less contextual awareness in pronunciation
Basic controls for speed, emotion and similarity
Standard audio quality without optimization
No on-device generation available
57
3-200 per mins
Voice Quality Comparison
When comparing voice quality between ElevenLabs and OpenAI Speech to Text, we found significant differences. ElevenLabs demonstrated high pronunciation accuracy, with 81.97% of words pronounced correctly, while OpenAI TTS achieved 77.30%. In terms of speech naturalness, ElevenLabs scored high in 44.98% of cases, whereas OpenAI TTS had a low naturalness rating in 78.01% of instances. Additionally, ElevenLabs had no detectable noise in 80.27% of its outputs, while OpenAI TTS maintained a similar standard with 89.46%. Overall, ElevenLabs provides a more natural and accurate voice quality experience.
Latency Assessment
In our latency evaluation, we measured the Time to First Audio (TTFA) for both ElevenLabs and OpenAI Speech to Text. We calculated the 90th percentile score from 100 TTFA measurements for each provider. ElevenLabs exhibited a TTFA of 150ms, indicating a quick response time, while OpenAI TTS recorded a TTFA of 200ms. This shows that ElevenLabs is more efficient in delivering audio output, making it a better choice for applications requiring low latency.
Hallucination Rate Analysis
The hallucination rate was assessed for ElevenLabs and OpenAI Speech to Text to determine how often the models generated incorrect or nonsensical outputs. ElevenLabs had a hallucination rate of 5%, indicating a strong performance in maintaining accuracy. In contrast, OpenAI TTS exhibited a higher hallucination rate of 10%. This evaluation suggests that ElevenLabs is more reliable in producing coherent and contextually appropriate speech, making it the preferred option for applications where accuracy is critical.
Voice Cloning
In our evaluation of voice cloning capabilities, ElevenLabs and OpenAI Speech to Text were put to the test. ElevenLabs achieved an impressive Word Error Rate (WER) of 2.83%, showcasing its accuracy in generating coherent speech. In contrast, OpenAI TTS recorded a WER of 3.36%, indicating slightly less precision. When it comes to speech naturalness, ElevenLabs scored high in 44.98% of cases, while OpenAI TTS struggled, with low naturalness in 78.01% of instances. This evaluation highlights ElevenLabs as the more effective choice for voice cloning applications, particularly in terms of accuracy and naturalness.
Voice Design Control
In evaluating voice design controllability, ElevenLabs and OpenAI Speech to Text were assessed on their ability to adapt voice characteristics based on user input. ElevenLabs scored high in context awareness, achieving a 63.37% rating, while OpenAI TTS lagged behind with a 39.25% score. Additionally, ElevenLabs demonstrated superior prosody accuracy at 64.57%, compared to OpenAI TTS's 45.83%. This indicates that ElevenLabs offers more flexibility and control in voice design, making it a better choice for customized voice applications.
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Pricing Comparison: ElevenLabs vs OpenAI TTS
ElevenLabs
Free - $0/mo. with 10k characters
Starter - $5/mo. with 30k characters
Creator - $11/mo. with 100k characters
Pro - $99/mo. per month with 500k characters
Scale - $330/mo. per month with 2M characters
OpenAI Speech to Text
TTS - $15 per 1M characters
TTS HD - $30 per 1M characters
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"This partnership represents a transformative moment in enterprise AI adoption," said Melissa Gordon, CEO of Rasa. "By combining Rasa’s strengths in enterprise conversational AI with Cartesia's innovative voice technology, we're fundamentally changing how enterprises can deploy and scale AI assistants across their organizations."
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Jeffrey Liu, Founder and co-CEO, Assort Health
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