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What is speech-to-text?

Converting recorded or live speech into text that software can search and act on.

3D render of a phone sending chat bubbles into a three lane CRM pipeline board

Definition

It writes down what was said, often with punctuation, timestamps and speaker labels. Batch mode handles finished files; streaming returns text while people speak.

Read more about Definition

Speech-to-text, also called automatic speech recognition (ASR), is software that listens to audio and writes down what was said. Good systems add punctuation, timestamps for each word or segment, and diarisation, which labels who spoke when ("Speaker 1", "Speaker 2").

It comes in two modes. Batch transcription processes a finished file such as a call recording or a WhatsApp voice note. Streaming transcription returns text while the person is still speaking, which voice agents need to reply quickly.

How it works

A neural network reads audio as a picture of frequencies and predicts the likeliest words. Accuracy is measured as word error rate.

Read more about How it works

Audio is cut into short frames and converted into a spectrogram, a picture of which frequencies are present over time. A neural network, typically an encoder that reads the audio and a decoder that writes tokens of text, predicts the most likely words. OpenAI's Whisper is a well-known open model of this kind and can run on your own hardware. Commercial APIs from Google, Microsoft, AWS, Deepgram and others offer the same job as a hosted service.

Accuracy is usually reported as word error rate (WER): substitutions, deletions and insertions divided by the number of words actually spoken. Lower is better.

Where it matters in business

Sales and support calls

Call transcripts become searchable, and an LLM writes summaries and next steps into the CRM.

Read more about Sales and support calls

Transcripts make calls searchable and let an LLM write the summary and next steps into the CRM.

Voice notes on WhatsApp

Transcribing voice notes lets one automation handle both voice and text messages.

Read more about Voice notes on WhatsApp

Field staff and customers send audio. Transcribing it lets the same automation handle voice and text messages.

Clinics and consultations

Dictated notes become draft records that a doctor reviews and signs.

Read more about Clinics and consultations

Dictated notes become draft records that a doctor reviews and signs.

Meetings and training

Searchable transcripts and subtitles for recorded meetings and training sessions.

Read more about Meetings and training

Searchable transcripts and subtitles for recorded sessions.

A practical example

Tamil and English sales calls are transcribed, an LLM fills four CRM fields, and a rep checks them before saving.

Read more about A practical example

A sales team in Chennai records calls in a mix of Tamil and English. Each recording is sent to a speech-to-text model, the transcript goes to a large language model with a short prompt, and the model fills four CRM fields: product interest, budget mentioned, objection and next follow-up date. A rep checks the fields before saving. The audio and transcript are kept for the period the company's retention policy allows, then deleted.

Common mistakes

Testing only on clean English

Mixed languages, accents, phone lines and noise raise errors. Test on your own recordings.

Read more about Testing only on clean English

Code-switching (Tamil and English, Hindi and English), accents, phone-line compression and background noise all raise the error rate. Test on your own recordings.

Skipping consent

Recording calls involves personal data. Tell callers and follow the DPDP Act or UK GDPR.

Read more about Skipping consent

Recording and transcribing calls involves personal data. Tell callers, and follow the DPDP Act 2023 in India or UK GDPR in the UK.

Trusting names and numbers blindly

Check phone numbers, amounts and codes against your records or with a person.

Read more about Trusting names and numbers blindly

Phone numbers, amounts and product codes are where errors cost money. Validate them against your records or ask a person to confirm.

Questions

Does speech-to-text work for Indian languages?

Yes, with varying quality. Whisper and the major cloud APIs support Hindi, Tamil and other Indian languages, and open projects from AI4Bharat focus on Indian languages specifically. Quality differs a lot by language and audio quality, so run a test on a sample of your own calls before choosing.

Can speech-to-text run offline?

Yes. Open models such as Whisper run on a local GPU or even a CPU for small volumes, so audio never leaves your network.

What is diarisation?

Diarisation splits a recording by speaker, so the transcript shows who said each line. It matters for calls and meetings where you need to know whether the customer or the agent said something.

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