Improve Voice Agent Pronounciation

Does your voice agent sound a bit… robotic? It’s a common hurdle. To make an AI sound truly human, you need to combine technical pronunciation tuning with strategic prompting. This guide covers everything from fixing mispronounced brand names to engineering realistic human speech patterns.

1. Fine-tuning Pronunciation

If your agent struggles with acronyms, technical terms, or web addresses, you can fix this in your Voice Channel settings under the Voice tab by clicking Fine-tune Pronunciation.

Method 1: The Alias Method (Beginner Friendly)

Simply replace words with phonetic spellings that sound right.

• @ → at

• NGINX → Engine-X

• CEO → Chief Executive Officer

• https:// → H T T P S colon slash slash

Method 2: The Phoneme Method (Advanced)

Use International Phonetic Alphabet (IPA) notation for surgical precision. This is ideal when the alias method doesn’t quite capture the right sound.

• WhatsApp → /wɒtsˈæp/

• Kubernetes → /ˌkuːbərˈneɪtiːz/

Pro Tip: Rules are case-sensitive. Add separate entries for "CEO" and "ceo" if your customers use both.

2. Prompting for Realism: How to Sound Human

The root issue of "robotic" AI is that LLMs are trained to produce clean, grammatically correct writing. Humans, however, speak with filler words, mid-sentence corrections, and pauses.

Define Natural Speech with Concrete Examples

Don't just tell the AI to "be conversational." Show it. Use your system prompt to provide "before and after" examples of how you want the agent to speak.

• Standard (Bad): "I can definitely handle that for you."

• Human-like (Good): "Yeah, um <break time="300ms"/> so, I can do that, no problem."

Engineer "Disfluencies" with Structured Pauses

Filler words like "um" only sound real if they are followed by a brief silence.

1. The Rule: Every time the agent says "um," immediately follow it with a <break time="300ms"/>.

2. The Recovery: After the pause, the agent should restart with a connector like "so" or "anyway."

3. The Result: "So <break time="300ms"/> um <break time="300ms"/> so... we're unfortunately going to have to cancel."

Emotion as a Constraint

Use emotion tags as guardrails. We've found that "peaceful" or "calm" tags often sound more human than "excited" tags, which can feel unstable.

• Authentic Reactions: Allow your agent to laugh using the [laughter] tag.

• Vocal Color: Encourage the agent to "narrate" its thoughts while looking things up: "Hmm, let me just check that <break time="500ms"/>. One second here..."

3. Personality as Behavior, Not Adjectives

Instead of telling the AI it is "friendly," give it a checklist of audible behaviors:

• Break Grammar Rules: Start sentences with "And," "But," or "So."

• Use "Like" and "Ya": Incorporate common verbal habits.

• Chill Confidence: Define the energy as "relaxed enthusiasm" rather than "corporate service."

• The "Loop Back": If the agent needs to return to a previous topic, prompt it to say: "About that other thing you mentioned..."

4. Quick Reference: Common Use Cases

Summary Checklist for Success

• [ ] Test Frequently: Use the "Test Agent" feature. What looks good in text might sound weird in audio.

• [ ] Start Simple: Use the Alias method first. Only move to IPA (Phonemes) if necessary.

• [ ] Repeat the Rules: LLMs need redundancy. Mention your "pause and filler word" rules multiple times in the system prompt.

• [ ] Publish Changes: Remember to click Publish for your new pronunciation and prompting rules to take effect in the live channel!