In the rapidly evolving landscape of artificial intelligence, text-to-speech (TTS) technology has made remarkable strides in recent years. For businesses implementing AI communication solutions like virtual receptionists, understanding the current capabilities and limitations of TTS is essential. Let’s explore the state of this technology in 2025 and how it’s transforming customer interactions.

The Leaders in TTS Technology

The text-to-speech market has several major players competing to deliver the most natural and versatile voice technologies:

ElevenLabs: Setting the Quality Standard

ElevenLabs has established itself as the quality leader in TTS technology. Their proprietary model can generate voices that are “almost indistinguishable from human speech” with just minutes of audio samples. This allows businesses to create custom voice personas with minimal source material.

Key strengths include:

• Support for over 30 languages
• Exceptional voice cloning capabilities
• Advanced emotional control
• A library of over 3,000 pre-built voices

Their recent expansion into speech-to-text with their Scribe model in February 2025 supports over 99 languages with a claimed 97% accuracy rate for English, making them a comprehensive voice AI provider.

OpenAI: Integrating Speech with Intelligence

OpenAI has been making significant inroads in the TTS space with their suite of voice models. Their approach focuses on integrating voice capabilities directly with their large language models.

Their Realtime API, launched in early 2025, takes a different architectural approach from competitors. Unlike the traditional pipeline of converting speech to text and then back to speech, OpenAI’s model “takes audio (speech) as input and provides audio (speech) directly as the output.” This preserves emotional context and reduces latency.

However, OpenAI currently offers fewer voice options (around 6) compared to ElevenLabs’ extensive library, and has more limited voice customization capabilities.

Deepgram: Focus on Enterprise Solutions

Deepgram has positioned itself as a serious competitor in the speech AI market with both speech-to-text and text-to-speech capabilities designed for enterprise applications. Their voice agent technology aims to provide comprehensive conversational AI solutions that integrate seamlessly with business systems.

Recent comparisons show that Deepgram’s Voice Agent can achieve “sub-second latency from end of speech to first byte” of response, making them comparable to OpenAI’s Realtime API for interactive voice applications.

Emerging Challengers

Several newer companies are challenging the established players:

• Smallest.ai: A relative newcomer claiming superior performance metrics. According to their own benchmark tests, they “surpass Eleven Labs in terms of latency” and achieve “higher MOS scores, particularly in categories that involve complex, multilingual, and culturally nuanced content.”

• Cartesia: Positioning themselves as offering “hallucination-free, ultra-realistic voice generation and cloning” with just 3 seconds of audio, their comparative testing shows they outperform both ElevenLabs and OpenAI on pronunciation accuracy and speech naturalness metrics.

Key Technical Advancements

1. Near-Human Quality

The most significant advancement in TTS technology has been the leap in quality. Modern TTS models can now “generate audio that is almost indistinguishable from human speech” with natural-sounding “emotions, pauses, and realistic tone.” This has eliminated the robotic quality that previously made AI voices immediately recognizable.

2. Reduced Latency

For real-time applications like AI receptionists, latency is critical. The leading models now achieve impressive response times:

• ElevenLabs’ Turbo v2 model claims latency under 400ms
• In comparative testing, ElevenLabs demonstrated a Time to First Audio (TTFA) of 150ms compared to OpenAI’s 200ms
• Smallest.ai claims to have the fastest response times in the industry

These improvements enable truly conversational interactions without awkward pauses.

3. Voice Cloning and Customization

The ability to create custom voices with minimal training data has transformed how businesses can personalize their communications:

• ElevenLabs requires just minutes of audio to create a convincing custom voice
• Cartesia claims to need only 3 seconds of audio for voice cloning
• Most providers now offer extensive customization options for emotion, tone, and speaking style

4. Language Support

Multilingual capabilities have expanded dramatically:

• ElevenLabs supports 30+ languages
• ElevenLabs’ Scribe speech-to-text model supports over 99 languages
• Most major providers now offer robust support for dozens of languages and accents

Current Limitations and Challenges

Despite impressive advances, TTS technology still faces some challenges:

1. Emotional Control

Even high-quality services like ElevenLabs still experience occasional “spikes” in emotion during generated audio and “unusual tone throughout a sentence,” particularly with shorter audio clips. Achieving consistent emotional delivery remains challenging.

2. Contextual Understanding

TTS technology often “struggles with understanding the context of a conversation, interpreting user intent, and managing dialogue flow.” This is particularly relevant for applications like AI receptionists that need to navigate complex customer interactions.

3. Pronunciation Challenges

Handling heterophone words (spelled the same but pronounced differently depending on context) remains difficult. For example, the word “polish” can be pronounced differently based on whether it refers to making something smooth or relating to Poland.

4. Hallucination Rates

Voice models can still produce errors or inconsistencies. In comparative testing, ElevenLabs showed a hallucination rate of 5%, while OpenAI TTS had a higher rate of 10%. While these percentages are improving, they can still impact customer experience in critical applications.

Implications for Business Communications

The advancements in TTS technology have significant implications for how businesses interact with customers:

AI Receptionists and Voice Agents

AI receptionists like those offered by Hi Kacy are at the forefront of applying these technologies. The combination of accurate speech recognition, natural-sounding voice synthesis, and conversational AI creates a seamless experience for callers.

With today’s TTS technology, an AI receptionist can:

• Answer calls with a warm, natural-sounding voice
• Understand and respond to customer questions with minimal latency
• Transfer calls and take messages with human-like interaction
• Operate 24/7 without quality degradation

Integration with Business Systems

Modern TTS systems can be integrated with:

• Customer relationship management (CRM) software
• Appointment scheduling systems
• Knowledge bases for accurate responses
• Analytics platforms for performance monitoring

This creates a comprehensive communication system that can handle most routine customer interactions autonomously.

Looking Forward: What’s Next for TTS

As we look to the future of TTS technology, several trends are emerging:

1. Further Reduction in Latency

The race to achieve the lowest latency possible continues, with companies like Smallest.ai and ElevenLabs pushing boundaries for real-time applications.

2. Improved Emotional Intelligence

Future TTS models will likely demonstrate better understanding of emotional context and more nuanced delivery of responses with appropriate tone and emphasis.

3. Domain-Specific Optimization

We expect to see more TTS models optimized for specific industries or use cases, such as healthcare, financial services, or customer support, with specialized vocabularies and interaction patterns.

4. Integration with Multimodal AI

The distinction between different AI capabilities is blurring. OpenAI’s approach of direct speech-to-speech processing demonstrates how future systems may integrate multiple modalities more seamlessly.

Conclusion: Why This Matters for Your Business

The remarkable advancements in text-to-speech technology are making AI communication solutions like Hi Kacy’s AI receptionist increasingly valuable for businesses of all sizes. With natural-sounding voices, rapid response times, and sophisticated conversational abilities, today’s AI receptionists can transform customer interactions while reducing operational costs.

As these technologies continue to improve, the distinction between human and AI communications will become increasingly subtle, opening new possibilities for businesses to provide exceptional service at scale, 24/7. The future of business communication isn’t just about automation—it’s about creating authentic, helpful interactions that strengthen customer relationships while optimizing resources.

For SMBs looking to stay competitive in 2025 and beyond, implementing an AI receptionist is no longer a futuristic luxury—it’s becoming an essential tool for business success.