---
title: FALCON Forced Aligner
emoji: 🦅
colorFrom: indigo
colorTo: blue
sdk: gradio
sdk_version: 4.44.1
python_version: "3.8"
app_file: app.py
pinned: true
license: mit
short_description: Neural forced alignment via Soft Dynamic Programming
thumbnail: https://huggingface.co/spaces/MLSpeech/FALCON/resolve/main/assets/app_screen.jpeg
---

# FALCON — Forced Alignment through Contrastive Optimization Networks

Interactive demo of **FALCON**, a fully differentiable neural forced aligner that predicts
precise **phoneme- and word-level** boundary timestamps from a waveform + transcript, using a
Soft Dynamic Programming decoder.

Upload audio + a transcript (`.phn` / `.wrd` / `.txt`), choose the options, and get a boundary
table, a downloadable Praat `.TextGrid`, and a time-aligned visualization (waveform ·
spectrogram · phoneme posteriors · Soft-DP path · contrastive score).

- **Paper:** *Fully Differentiable Neural Forced Alignment via Soft Dynamic Programming* — [arXiv:2606.25460](https://arxiv.org/abs/2606.25460)
- **Code:** https://github.com/MLSpeech/FALCON
- **Weights:** https://huggingface.co/MLSpeech/FALCON-weights

Example inputs are in `assets/` — the TIMIT sentence *"Don't ask me to carry an oily rag like that."*
in every supported format. The checkpoints are downloaded automatically from the weights repo on
first use (this runs on a free CPU Space, so the first alignment takes a moment to fetch a model).


## Example alignments

The app's own output (waveform · spectrogram · phoneme posteriors · Soft-DP path ·
contrastive score) on real test utterances. Bundled inputs are in `assets/examples/`.

**English — TIMIT** (read speech, phoneme-level)

![English](https://huggingface.co/spaces/MLSpeech/FALCON/resolve/main/assets/example_english.png)

**Dutch — IFA** (zero-shot cross-lingual, phoneme-level)

![Dutch](https://huggingface.co/spaces/MLSpeech/FALCON/resolve/main/assets/example_dutch.png)

**German — PHONDAT** (zero-shot; figure only — PHONDAT is licensed by BAS, not redistributed)

![German](https://huggingface.co/spaces/MLSpeech/FALCON/resolve/main/assets/example_german.png)

**Hebrew** (zero-shot, word-level, romanized transcript, no G2P model)

![Hebrew](https://huggingface.co/spaces/MLSpeech/FALCON/resolve/main/assets/example_hebrew.png)

Example audio is for demonstration only and remains subject to each corpus's original
license — see `assets/examples/NOTICE`.