SpAudSyn (Spatial Audio Synthesizer): a library for spatial sound scenes synthesis

Introduction

SpAudSyn is a Python library for synthesizing multichannel audio mixtures from single-channel sources.

Originally developed for dcase2026_task4_baseline of DCASE 2026 Task 4, SpAudSyn is flexible and adaptable to tasks such as sound event detection and localization. It supports configurable outputs (e.g., labels, dry sources, metadata, RIRs) and is optimized for on-the-fly mixture generation. In addition, each mixture can be fully parameterized and saved as a JSON file, enabling exact reconstruction and reproducible experiments.

Installation

Install the requirements

pip install -r requirements.txt

Place the library folder into your project and import SpAudSyn from src/spatial_audio_synthesizer.py.

Data Organization

SpAudSyn requires input data organized into four directories:

• foreground_dir: Contains foreground single-channel source audio files (target signals).
• interference_dir: [optional] Contains single-channel non-target or interfering sources.
• background_dir: [optional] Contains multichannel background noise recordings.
• sofa_dir: Contains room impulse responses (RIRs) stored as SOFA files.

To synthesize a mixture, SpAudSyn loads single-channel sources from foreground_dir (and optionally from interference_dir), convolves with RIRs from sofa_dir, and adds multichannel background noise from background_dir.

The foreground_dir is organized as follows:

foreground_dir
|-- Class_label_1
|   |-- source_1.wav
|   |-- object
|   |   |-- object_source1.wav
|   |   |-- object_source2.wav
|   |   `-- ...
|   `-- ...
|-- Class_label_2
|   |-- source_1.wav
|   `-- source_2.wav
`-- ...

The foreground_dir contains multiple subdirectories, where each subdirectory corresponds to a Class_label.
All .wav files belonging to a given class can be placed anywhere within that class’s directory, including nested subdirectories.

The interference_dir has a structure similar to foreground_dir. Noise recordings and RIR SOFA files can be placed anywhere within background_dir and sofa_dir, respectively.

Example

An example notebook demonstrating how to use SpAudSyn is available at: example/example.ipynb.

This example uses data from dcase2026_task4_baseline. To run the example, place the data folder into the SpAudSyn repository as follows

ln -s path/to/dcase2026_task4_baseline/data path/to/SpAudSyn

Citation

If you use this library and/or the dataset, please cite the following paper:

@article{yasuda2026dcase,
  title={Description and Discussion on DCASE 2026 Challenge task 4: Spatial Semantic Segmentation of Sound Scenes},
  author={Yasuda, Masahiro and Nguyen, Binh Thien and Harada, Noboru and Serizel, Romain and Mishra, Mayank and Delcroix, Marc and Carlos, Hernandez-Olivan and Araki, Shoko and Takeuchi, Daiki and Nakatani, Tomohiro and Ono, Nobutaka},
  journal={arXiv preprint arXiv:2604.00776},
  year={2026},
  url={https://arxiv.org/pdf/2604.00776}
}