prompting silk mulberry 1.5

mulberry is steered by a description: one natural sentence that says how the voice should sound. write the voice you want, then your spoken text. hear one:

the description formula

weave the attributes into one sentence instead of listing them as fields. a useful shape is:

a {gender} {age} {accent} voice, {pitch} pitch, {timbre}, {pacing} pacing, {emotion}, {register} register, like a {role}.

the {...} parts are placeholders you fill in. mention only the ones you care about; the model fills in the rest.

a deep male 30s indian voice, slow pacing, formal register, like a corporate training narrator.

30s. indian. deep. slow. formal. corporate narrator.

hear different voices

each one follows the formula. press play, and copy any sample to start from it.

saying numbers, IDs and dates. silk normalizes your text before speaking it, so amounts, dates, times and percentages are read out for you. anything that must be read digit by digit, like an OTP or an order number, has to be wrapped in double quotes. your description is never touched. see numbers, IDs & dates.

send it

put the voice in description and your spoken text in text. add speaker to use a preset voice instead of a description.

curl -X POST https://silk-api.rumik.ai/v1/tts \
  -H "Authorization: Bearer rk_live_•••••••••" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "mulberry",
    "text": "आज का episode थोड़ा अलग है।",
    "description": "a female 30s hindi voice, smooth timbre, conversational pacing, casual register, like a podcast host"
  }' \
  --output mulberry.wav

import requests

resp = requests.post(
    "https://silk-api.rumik.ai/v1/tts",
    headers={"Authorization": "Bearer rk_live_•••••••••"},
    json={
        "model": "mulberry",
        "text": "आज का episode थोड़ा अलग है।",
        "description": "a female 30s hindi voice, smooth timbre, conversational pacing, casual register, like a podcast host",
    },
)
with open("mulberry.wav", "wb") as f:
    f.write(resp.content)

const resp = await fetch("https://silk-api.rumik.ai/v1/tts", {
  method: "POST",
  headers: {
    Authorization: "Bearer rk_live_•••••••••",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "mulberry",
    text: "आज का episode थोड़ा अलग है।",
    description:
      "a female 30s hindi voice, smooth timbre, conversational pacing, casual register, like a podcast host",
  }),
});
const fs = require("fs");
fs.writeFileSync("mulberry.wav", Buffer.from(await resp.arrayBuffer()));

see the API reference for the full request schema.

voice attributes

mention any of these in your description. write hindi words in devanagari and english words in latin, e.g. आज का episode थोड़ा अलग है.

gender: male, female
age: 20s, 30s, 40s
pitch: low, normal, high
pacing: very slow, slow, conversational, brisk, fast, very_fast
emotion: neutral, energetic, excited, sad, sarcastic, dry, crying, angry
intensity: low, med, high
register: formal, neutral, casual

accents

global: american, british, middle_eastern, asian_american, indianindian regional: hindi, punjabi, bihari, south_indian, bengali, rajasthani, marathi, gujarati, kashmiri, assamese, odia, telugu, kannada, malayali, haryanvi, chhattisgarhi

timbre

realistic: deep, warm, gravelly, smooth, raspy, nasally, throaty, harsh, whispercreative: adds robotic, ethereal to the realistic set

speaking roles

pick a role from a domain to anchor the delivery style.

social: youtube_vlogger, social_media_creator, influencer_voice, streamer_companion
podcast: podcast_host, interviewer
commercial: ad_narrator, brand_spokesperson, product_demo_voice, sales_pitch_voice
education: elearning_instructor, kids_story_voice
support: customer_support_agent, virtual_receptionist, healthcare_assistant
entertainment: storyteller, social_media_reaction, meme_voice
corporate: explainer_video_voice, event_host, corporate_training_narrator
viral: short_form_narrator, meme_voice

creative-only attributes

available when you want a non-realistic timbre (characters, stylized voices):

animated_cartoon  ai_machine_voice  alien_scifi  seductively  flirty  anime
cyborg  pirate  dark_villain  demon  gangster  mafia  dramatic_narrator
mythical_godlike_magical  spy  vampire  alpha

inline tags

drop these in the text to trigger a sound. they render as part of the performance, not as words.

<laugh>  <laugh_harder>  <sigh>  <chuckle>  <gasp>  <angry>  <excited>
<whisper>  <cry>  <scream>  <sing>  <snort>  <exhale>  <gulp>  <giggle>
<sarcastic>  <curious>

preset voices

your description is always required, and on its own it’s what the voice is built from. add speaker to pin one of the twelve named voices instead:

voice	gender
`emma` `mia` `sophia` `ava` `ira` `siya` `aisha` `zoya`	female
`lucas` `noah` `theo` `adam`	male

names are case-insensitive, and description still goes with the request. see the mulberry page for a full request.

using mulberry in a voice agent

mulberry reads a complete sentence or utterance at once, not a running token stream. but it streams the audio out, so the first audio comes back before the whole line finishes synthesizing. wait until your LLM has a full sentence, send that, and stream the audio to the caller. that makes it a good fit for low-latency conversational agents. keep one voice across the conversation. the description defines the voice, so for a given bot send the same description string on every request. reusing it keeps the persona consistent turn to turn. a preset speaker is the other way to pin a fixed voice. an unknown or misspelled inline tag is spoken literally, not rejected, so validate the text before production. for transport, see streaming and the pipecat integration.

system prompt for your agent’s LLM

hand this to the LLM that writes mulberry’s lines. tune the wording, not the attributes.

You write voice descriptions and spoken text for the silk mulberry 1.5
text-to-speech model.

- "description" is ONE natural sentence describing the voice. Weave 3 to 5
  attributes together; never list them as separate fields.
- Draw attributes from these only: gender (male/female); age (20s/30s/40s);
  accent (e.g. american, british, indian, hindi, punjabi, bengali, south_indian);
  pitch (low/normal/high); timbre (deep, warm, gravelly, smooth, raspy, ...);
  pacing (slow, conversational, fast, ...); emotion (neutral, energetic, excited,
  sad, ...); register (formal, neutral, casual); and an optional role
  (e.g. podcast_host, customer_support_agent, storyteller).
- "text" is the spoken line: Hindi words in Devanagari, English words in Latin.
- You may add inline tags such as <laugh>, <sigh>, <chuckle> inside "text".

Return JSON: { "description": "...", "text": "..." }

common mistakes

most “the voice ignored me” cases trace back to one of these:

what you hear	likely cause	fix
an attribute is ignored	the description lists fields, or packs in too many	write one sentence with 3 to 5 attributes
the accent is wrong	the accent is not in the supported vocabulary	pick one from the accent list above (global or regional)
the voice sounds generic	the description is too vague	add an age, an accent, a timbre, and a role
a tag is read aloud as a word	the tag is misspelled or not in the supported set	use an exact tag from the inline tags list
pacing or pitch is off	a value outside the listed vocabulary	use the listed `pacing` and `pitch` values
the audio is cut off early	the line needs more tokens than the default cap	raise `max_new_tokens` (default `2048`, up to `8192`)

faq

how detailed should the description be?

one sentence with 3 to 5 attributes beats a paragraph of vague adjectives. mention only what you care about; the model fills in the rest.

description or preset speaker?

it isn’t either/or. description is always required; send it every time. on its own, the voice is generated from it. add speaker when you want one of the twelve named voices instead of a generated one.

how do I keep the same voice across a conversation?

send the identical description on every request for that bot. pinning a speaker as well makes it steadier still.

can I add laughs and sighs?

yes. drop inline tags like <laugh>, <sigh>, <chuckle> directly in the text where you want the sound.

documentation

SDK

integrations

cookbook

API reference

prompting silk mulberry 1.5

the description formula

hear different voices

send it

voice attributes

inline tags

preset voices

using mulberry in a voice agent

system prompt for your agent’s LLM

common mistakes

faq

​the description formula

​hear different voices

​send it

​voice attributes

​inline tags

​preset voices

​using mulberry in a voice agent

​system prompt for your agent’s LLM

​common mistakes

​faq

the description formula

hear different voices

send it

voice attributes

inline tags

preset voices

using mulberry in a voice agent

system prompt for your agent’s LLM

common mistakes

faq