I’m trying to generate speech using gpt-4o-mini-tts with onyx voice and the following instructions: Talk as a 38 year old Male with strong Boston accents. Delivery: Natural conversational with strong Boston accents Emotion: reserved However, it doesn’t seem to work. Anyone has a trick to make i…

Check out this thread: [image] TTS no longer follows instructions parameter Bugs From about a month ago the text to speech api is no longer following the instructions parameter. No matter what instructions I enter, the speech is always the same. It happens bot…

This, and also for a more concrete prompt maybe use: “Adult male from Greater Boston. Non-rhotic (drop post-vocalic R), slightly flattened/clipped vowels, casual conversational rhythm, reserved emotion, no caricature.” Oh and sparingly add in a couple hints where you type it how it sounds, like: “…

Accents can be tricky with TTS models. In my experience, breaking the voice instructions into very simple, direct traits and avoiding age or emotional overload sometimes helps. Also worth experimenting with phonetic hints or example phrases typical to the region.

gpt-4o-mini-tts was updated and it’s broken now and doesn’t follow TTS instructions most of the time. You can get the old behavior back by using gpt-4o-mini-tts-2025-03-20

Voice Instruction with gpt-4o-mini-tts

Prompting

jeffvpace January 20, 2026, 5:07pm 2

Check out this thread:

Topic		Replies	Views
[gpt-4o-mini-tts] Instructions leaking into generated audio Bugs	4	470	August 4, 2025
TTS no longer follows instructions parameter Bugs	12	875	February 13, 2026
Instructions missing in TTS-1-HD? API	3	299	August 12, 2025
British accent and pronuciation in gpt-4o-mini-tts API tts	4	3035	March 25, 2025
Audio Models in the API - live stream at 10 AM PT API	14	1328	March 29, 2025

Voice Instruction with gpt-4o-mini-tts

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