Structured Data in Voice AI: Stop Commas From Being Read Out Loud.

Ever tested a voice AI agent and wondered why it reads commas out loud after a website or email address, but never in normal sentences?

This subtle but frustrating quirk isn’t random.

It comes down to how the voice engine’s normalizer processes punctuation differently for structured data (like URLs, emails, and phone numbers) versus regular text.

Following is a part of the System Prompt used for Voice AI Agent:

### 2. Lead Capture Order  

Use acknowledgment, encouragement, and backchannels after each answer, then confirm before moving to the next question.  

- Website Address:  

  "What’s your business’s website address, please?"  

  (“Alright,” “I see.”)  

  "And just to make sure I’ve got it, that’s [repeat website] right?"  

  (Wait for confirmation.)

Here,

The placeholder [repeat website] means:

• The voice AI agent should repeat back whatever website address the caller just provided.
• It’s not literal text. It’s a dynamic slot/variable that gets filled in at runtime.

Example flow.

Caller: “My website is www.james.com.”

Agent: “Alright. And just to make sure I’ve got it, that’s www.james.com, right?”

Here, www.james.com is substituted into [repeat website].

Placeholders = variables that get replaced at runtime with the caller’s input.

When you test the agent, the voice agent says:

“What’s your business’s website address, please?” → without speaking the comma,

but when confirming:

“And just to make sure I’ve got it, that’s [repeat website] right?” → The agent speaks the comma.

But why?

The difference you’re noticing comes from how the normalizer (the component used by the voice AI Agent to prepare the response) processes punctuation.

In normal sentences (e.g., “What’s your business’s website address, please?”), the normalizer treats the comma as a pause marker, so the TTS (the component used by the voice AI Agent to speak the response) simply adds a short pause.

The comma is never spoken aloud.

But

when structured data (like www.james.com) is followed by punctuation, the normalizer applies verbatim like rules.

Structured values are read literally (dot → “dot,” @ → “at,” etc.).

If punctuation is placed immediately after the structured value, the normalizer glues it to the value instead of treating it as normal grammar.

This overlap makes the comma (or period) “stick” to the structured data.

Depending on the engine and context, the agent may speak it or at least show it as attached in the transcript.

In short:

Normal sentence commas = pauses only.

Structured data + punctuation immediately after = punctuation treated as part of the value, sometimes even spoken aloud.

The fix.