SATB separation guide

Hear every voice in the choir.

Cantor is a browser-based AI choir stem separator. It turns a mixed vocal harmony recording into individual soprano, alto, tenor, and bass tracks for rehearsal, transcription, and closer listening.

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What Cantor is for

When the voices blend together, it can be hard to pick out a single part. Choir directors can use Cantor to prepare rehearsal tracks, singers can practise their line, and arrangers and researchers can listen closely to overlapping harmonies.

Cantor produces audio tracks, with one stem for each selected voice. It doesn't generate a written score.

Supported recordings and formats

Voices: Soprano, alto, tenor, and bass, including recordings that contain only a selected subset.
File formats: WAV, FLAC, MP3, M4A, OGG, and OPUS within the current upload limit.
Online sources: Use a supported public YouTube link in the app.
Output: Separate WAV stems with browser preview and download controls.
Processing: The complete source or a selected time region can be processed.

Where results can be weaker

Separation is most reliable when SATB parts are clearly sung and the recording has limited room echo, distortion, and accompaniment. When a source also contains instruments or a prominent lead vocalist, it may first need separate stages to isolate the vocal ensemble before Cantor can extract the SATB parts.

Stage 1 Full music mix Choir, lead vocal, and instruments overlap.

Stage 2 Isolate ensemble vocals Instrumental and lead-vocal separation may introduce artefacts.

Stage 3 Extract SATB parts Cantor works with the audio preserved by the earlier stages.

Every additional separation stage can remove or alter useful vocal detail. Instrument bleed, missing harmonics, softened consonants, phase artefacts, and traces of the lead vocal can therefore carry into the SATB result. For the best quality, use the cleanest choir or backing-vocal recording available and avoid unnecessary preprocessing.

Results can also be weaker with dense unison singing, unusual voice ranges, heavy pitch correction, clipping, crowd noise, or strong reverberation. Overlapping voices may leave traces in another stem.

Cantor is a research preview. Listen critically before using a stem for teaching, performance decisions, publication, or research conclusions.

A real Cantor audio example

This is an actual 30-second separation, not a reconstruction or mock-up. Start with the mixture, then compare each generated voice stem.

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Source audio: Cantoría Dataset, licensed CC BY 4.0. Separation by Cantor.

Privacy and retention

Your recordings and account data are private. Uploaded audio and separated stems are stored for up to 30 days so you can reopen results or run another separation. You can delete a separation's stored audio sooner. Audio is not used for model training without separate, explicit consent.

Cantor records aggregate daily referral-source totals for public marketing pages. It does not store a visitor's full referring URL, IP address, device fingerprint, or live-presence record for this measurement. Read the full privacy notice.

Get started with 15 credits

Cantor is in beta. Confirm your email to create an account and start with 15 credits, with no card required. Each credit covers one minute of your recording and includes all four voices. Duration is rounded to the nearest minute, with a one-credit minimum.

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