Voice Changer

Apply real-time voice effects and transformations to any audio.

Overview

The Voice Changer API lets you transform audio with a library of built-in effects and fine-grained controls for pitch, intensity, and format. Process recordings or pipe in live audio for real-time transformations.

7 effect presets (deep, high, robotic, whisper, echo, chipmunk, radio)

Intensity control

Pitch shifting

Real-time processing

Multiple formats

Custom effects

Quickstart

Apply an effect to an audio file in just a few lines of code.

from nur import NurClient
client = NurClient()
# Apply a robotic effect to an audio file
result = client.voice_changer.transform(
    file="recording.mp3",
    effect="robotic",
    intensity=0.8,
    pitch_shift=0.0,
    output_format="mp3"
)
print(f"Transformed audio: {result.audio_url}")
print(f"Duration: {result.duration}s")
print(f"Effect: {result.effect_applied}")

Transform Audio

POST/v1/voice-changer/transform

Apply a voice effect to an uploaded audio file. You can control the effect intensity, apply pitch shifting, and choose the output format. Supports WAV, MP3, FLAC, and OGG inputs.

Parameter	Type	Description
fileREQUIRED	file	Audio file to transform (WAV, MP3, FLAC, OGG)
effectREQUIRED	string	Effect preset: deep, high, robotic, whisper, echo, chipmunk, or radio
intensity	number	Effect strength from 0.0 to 1.0. Defaults to 0.5
pitch_shift	number	Pitch adjustment in semitones (-12 to 12). Defaults to 0
output_format	string	Output format: mp3, wav, flac, or ogg. Defaults to mp3

curl -X POST https://api.nur.ai/v1/voice-changer/transform \
  -H "Authorization: Bearer $NUR_API_KEY" \
  -F "file=@recording.mp3" \
  -F "effect=deep" \
  -F "intensity=0.7" \
  -F "pitch_shift=-3" \
  -F "output_format=wav"

Response

{
  "audio_url": "https://cdn.nur.ai/voice-changer/vc_def789/output.wav",
  "duration": 12.4,
  "effect_applied": "deep",
  "intensity": 0.7,
  "format": "wav"
}

List Effects

GET/v1/voice-changer/effects

Retrieve a list of all available voice effect presets. No parameters required. Each effect includes a description, default intensity, and a preview audio URL.

curl -X GET https://api.nur.ai/v1/voice-changer/effects \
  -H "Authorization: Bearer $NUR_API_KEY"

Response

{
  "data": [
    {
      "name": "deep",
      "description": "Lowers pitch for a deeper, resonant voice",
      "default_intensity": 0.5,
      "preview_url": "https://cdn.nur.ai/effects/deep_preview.mp3"
    },
    {
      "name": "high",
      "description": "Raises pitch for a lighter, higher voice",
      "default_intensity": 0.5,
      "preview_url": "https://cdn.nur.ai/effects/high_preview.mp3"
    },
    {
      "name": "robotic",
      "description": "Adds a synthetic, robotic modulation",
      "default_intensity": 0.6,
      "preview_url": "https://cdn.nur.ai/effects/robotic_preview.mp3"
    },
    {
      "name": "whisper",
      "description": "Converts speech to a soft whisper",
      "default_intensity": 0.7,
      "preview_url": "https://cdn.nur.ai/effects/whisper_preview.mp3"
    },
    {
      "name": "echo",
      "description": "Adds spatial echo and reverb",
      "default_intensity": 0.4,
      "preview_url": "https://cdn.nur.ai/effects/echo_preview.mp3"
    },
    {
      "name": "chipmunk",
      "description": "High-speed pitch shift for a chipmunk effect",
      "default_intensity": 0.8,
      "preview_url": "https://cdn.nur.ai/effects/chipmunk_preview.mp3"
    },
    {
      "name": "radio",
      "description": "Simulates vintage AM/FM radio frequency response",
      "default_intensity": 0.5,
      "preview_url": "https://cdn.nur.ai/effects/radio_preview.mp3"
    }
  ]
}

Effects Reference

Overview of all built-in effect presets and their characteristics.

Effect	Description	Default Intensity	Best For
deep	Lowers pitch for a resonant voice	0.5	Narration, trailers
high	Raises pitch for a lighter voice	0.5	Character voices
robotic	Synthetic modulation	0.6	Sci-fi, games
whisper	Soft whisper conversion	0.7	ASMR, storytelling
echo	Spatial echo and reverb	0.4	Ambience, music
chipmunk	High-speed pitch shift	0.8	Comedy, entertainment
radio	Vintage AM/FM simulation	0.5	Podcasts, retro style

Response Objects

Reference for the objects returned by Voice Changer endpoints.

Transform Result Object

Field	Type	Description
audio_url	string	URL to download the transformed audio file
duration	number	Duration of the output audio in seconds
effect_applied	string	Name of the effect that was applied
intensity	number	Intensity level that was used (0.0 to 1.0)
format	string	Output format of the audio file

Best Practices

Start with moderate intensity

Begin with the default intensity value for each effect and adjust incrementally. High intensity values can introduce artifacts, especially with the robotic and echo presets. Values between 0.4 and 0.7 usually produce the most natural results.

Combine pitch shift with effects thoughtfully

Pitch shifting works independently from effect presets. A subtle pitch shift of 1-2 semitones combined with an effect can produce unique results, but large shifts paired with heavy effects may degrade audio quality.

Choose the right output format

Use WAV for maximum quality when processing audio further downstream. Use MP3 for smaller file sizes in web delivery. FLAC offers lossless compression if you need both quality and reduced file size.

Use clean source audio

Effects are most effective when applied to clean recordings with minimal background noise. Consider running audio through the Nur denoiser endpoint first if the source contains unwanted ambient sound.