What is sentiment analysis in speech-to-text?

Sentiment analysis in speech-to-text labels each part of a transcript as positive, negative, neutral, or mixed, often with an emotion such as anger or relief. Applied to calls, it’s the core of modern customer sentiment analysis, and it’s one of the fastest ways to improve customer experience from call data.

Can Gladia flag negative sentiment on live calls for supervisor alerts?

Yes. With real-time transcription, Gladia sends a sentiment analysis event for each finalized utterance, so you can alert a supervisor the moment a caller turns negative, while the call is still live.

Can sentiment analysis identify escalating customers in call center recordings?

Yes. Gladia scores every sentence in a recording, so you can see where a customer’s sentiment turns negative and stays there. Across thousands of calls, those scores show trends that contact centers use to map call sentiment to CSAT and other CX metrics.

How do I analyze sentiment for each speaker, including agents?

Turn on speaker diarization in the same pre-recorded request, and every sentiment result is tagged with a speaker. That lets you flag aggressive agent turns separately from customer frustration, the same way meeting tools combine diarization and emotion analysis to show how each participant reacted.

What’s the best tool for real-time call transcription and sentiment analysis?

Look for sentence-level scoring, per-speaker results, real-time support, and an accurate transcript underneath, since transcription errors flip labels. Our comparison of the best tools for call transcription and sentiment analysis breaks down how providers differ. Contact center teams building LLM-based bots usually choose an API that streams the transcript and sentiment together over per-seat software.

Does Gladia’s sentiment analysis detect tone of voice?

Gladia’s sentiment analysis reads the transcript, so it scores what people say rather than how they sound. That makes accurate transcription essential, which is why it runs on Solaria-3, the top-ranked model on real customer calls. The full list of labels is in the sentiment analysis docs.

Which emotions can Gladia detect?

Gladia returns one of 25 emotion labels per sentence, including anger, confusion, disappointment, interest, relief, and sympathy, alongside its sentiment. The full label list is in the docs.

Does sentiment analysis cost extra?

No. Sentiment analysis is included in Gladia’s per-hour rate for both async and real-time, with no add-on fee on any pricing plan.

Audio intelligence

Sentiment analysis

Turn on sentiment analysis with a single parameter and label every sentence of your calls and meetings as positive, negative, neutral or mixed, plus 25 emotions. It works on live streams and recorded files, and with diarization you'll see how each speaker felt.

Get your API keyGet your API key

50€

Transcription credits

Test customer sentiment analysis on your own calls. No expiry, no credit card.

Speaker diarization

Top of DIHARD III against 9 providers. Every sentence, matched to the right speaker.

100+

Languages

Analyze customer sentiment in 100+ languages, with no separate tool per market.

Trusted by over 350,000 users and 2,000+ enterprise teams

Sentiment and emotion for every sentence

See exactly where a conversation turns. Gladia’s sentiment detection scores each sentence instead of the whole call, with timestamps and speaker labels, so you can jump straight to the moment a customer was frustrated.

Sentence-level sentiment examples
Sentence	Speaker	Sentiment	Emotion
“I’ve been charged twice for the same order.”	Customer	Negative	Anger
“I’m sorry about that, let me check your account.”	Agent	Neutral	Sympathy
“I’ve refunded the duplicate charge just now.”	Agent	Positive	Neutral
“Oh, great, that was quick. Thank you.”	Customer	Positive	Relief

Explore all sentiment and emotion values

Accurate sentiment starts with accurate transcripts

Every sentiment label is built on the transcript underneath it. Mishear one word and a label can flip; confuse two speakers and the emotion lands on the wrong person. That’s why transcription and diarization accuracy matter here.

Real customer audio

English production calls

Human-annotated customer calls. WER% results.

Solaria-39.6%

ElevenLabs9.9%

AssemblyAI10.0%

Deepgram10.7%

Switchboard

Conversational speech

Unscripted two-party telephone speech. WER% results.

Solaria-333.9%

AssemblyAI42.3%

Speechmatics46.0%

Deepgram49.8%

DIHARD III

Diarization

Speaker diarization across 10 recording domains. Weighted avg. DER results.

Solaria-116.6%

Speechmatics30.1%

AssemblyAI43.9%

Deepgram46.9%

See the full benchmark

Add sentiment analysis in one parameter

Replace a separate sentiment analysis tool with one flag on your transcription request. Results come back aligned to the transcript, with nothing to pass between services.

Send your audio

Upload a file, pass a URL, or open a real-time WebSocket session.

Enable sentiment analysis

Set "sentiment_analysis": true. For live sessions, add it under realtime_processing and turn on real-time processing events.

Get scored sentences

Each sentence returns its sentiment, emotion, and timestamps. Turn on diarization for pre-recorded audio to tag each result by speaker.

Read the sentiment analysis docs

Use cases

Sentiment analysis for every customer conversation

Most teams only review a sample of their calls. Sentiment analysis covers all of them, flagging frustration, satisfaction, and the moments a conversation changes direction.

Meeting assistants

Show how prospects and teammates reacted to each topic, so sales and customer success teams know where a deal stands.

Learn more →

Contact centers (CCaaS)

Flag negative turns as they happen, prioritize calls for QA, and connect sentiment to CSAT across every interaction.

Learn more →

Voice agents

Detect rising frustration mid-call and hand off to a human before the customer hangs up.

Learn more →

Measuring how customers feel on calls?

Follow a practical guide to building a sentiment pipeline that holds up on noisy, multilingual audio.

Read the guide →

The Gladia team is unrivaled in both customer support and product quality. They are always available to help us and proactively reach out. With their add-ons and high-quality transcription, they are true innovators in the audio space, building something people genuinely want.

Sentiment analysis free with every transcript

Score every call instead of a sample, for the same rate. Sentiment analysis is included in every plan at no extra cost, unlike separate sentiment analysis software.

Starter

Flexible pay-as-you-go for moderate audio volumes. Get started immediately.

Async at $0.61/hr

Real-time at $0.75/hr

* 50€ in free credits

Get started

Growth

Lower unit pricing for fast-growing teams. Commit upfront to unlock savings.

Async as low as $0.20/hr

Real-time as low as $0.25/hr

* 67% less than Starter

Enterprise

Annual plan with custom models, fine-tuning, debundled pricing, and more.

Custom

Explore the pricing

Know how every conversation felt

Start free with 50€ in credits, or book a demo to test sentiment analysis on your own calls.

FAQs

Sentiment analysis in speech-to-text labels each part of a transcript as positive, negative, neutral, or mixed, often with an emotion such as anger or relief. Applied to calls, it’s the core of modern customer sentiment analysis, and it’s one of the fastest ways to improve customer experience from call data.
Yes. With real-time transcription, Gladia sends a sentiment analysis event for each finalized utterance, so you can alert a supervisor the moment a caller turns negative, while the call is still live.
Yes. Gladia scores every sentence in a recording, so you can see where a customer’s sentiment turns negative and stays there. Across thousands of calls, those scores show trends that contact centers use to map call sentiment to CSAT and other CX metrics.
Turn on speaker diarization in the same pre-recorded request, and every sentiment result is tagged with a speaker. That lets you flag aggressive agent turns separately from customer frustration, the same way meeting tools combine diarization and emotion analysis to show how each participant reacted.
Look for sentence-level scoring, per-speaker results, real-time support, and an accurate transcript underneath, since transcription errors flip labels. Our comparison of the best tools for call transcription and sentiment analysis breaks down how providers differ. Contact center teams building LLM-based bots usually choose an API that streams the transcript and sentiment together over per-seat software.
Gladia’s sentiment analysis reads the transcript, so it scores what people say rather than how they sound. That makes accurate transcription essential, which is why it runs on Solaria-3, the top-ranked model on real customer calls. The full list of labels is in the sentiment analysis docs.
Gladia returns one of 25 emotion labels per sentence, including anger, confusion, disappointment, interest, relief, and sympathy, alongside its sentiment. The full label list is in the docs.
No. Sentiment analysis is included in Gladia’s per-hour rate for both async and real-time, with no add-on fee on any pricing plan.

Sentiment analysis

Transcription credits

Speaker diarization

Languages

Sentiment and emotion for every sentence

Accurate sentiment starts with accurate transcripts

English production calls

Conversational speech

Diarization

Add sentiment analysis in one parameter

Send your audio

Enable sentiment analysis

Get scored sentences

Sentiment analysis for every customer conversation

Meeting assistants

Contact centers (CCaaS)

Voice agents

Measuring how customers feel on calls?

Sentiment analysis free with every transcript

Starter

Growth

Enterprise

More capabilities

Audio-to-LLM

Code-switching

Custom vocabulary

Know how every conversation felt

FAQs