python-peass 2.0.1

python-peass: Perceptual Evaluation methods for Audio Source Separation

python-peass

This project was ported by Gemini 3.5 Flash from https://gitlab.inria.fr/bass-db/peass/-/tree/22c7fc4ef670f8bb6eea9ab4abea98323006b769/v2.0.1

An elegant, Pythonic, and fully-typed port of the PEASS v2.0.1 (Perceptual Evaluation methods for Audio Source Separation) toolkit [1].

This library replaces traditional energy ratios (SDR, SIR, SAR) with perceptually motivated objective scores— OPS, TPS, IPS, and APS—which are highly correlated with human evaluations [1].

Scientific Highlights

Traditional metrics evaluate separations via energy ratios [1]. However, human hearing relies heavily on non-linear auditory transduction and masking [2]. python-peass executes a multi-stage cognitive pipeline to assess quality:

1. Subband Least-Squares Decomposition: Signals are divided into subbands using a complex-valued Hohmann Gammatone Filterbank [1, 3]. Overlapping temporal frames are projected onto estimated subspaces to isolate physical distortion artifacts [1].
2. Inner Hair Cell Transduction: Approximates the shearing limits of physical hair bundles via half-wave rectification and 1 kHz membrane-limit lowpass filters [1, 2].
3. Auditory Nerve Adaptation: Uses five stages of non-linear feedback loops modeling forward masking and metabolic neural depletion [2].
4. Perceptual Assimilation: Models cognitive masking where noise below a target threshold is partially assimilated or masked [2].
5. Score Prediction: Feeds weighted similarity percentiles into a multi-criteria trained sigmoidal neural network to output scores from 0 to 100 [1].

Architectural Layout & MATLAB Mapping

Unlike loose research scripts, this package organizes functions into explicit scientific modules:

Python Module	Primary Classes / Functions	Replaced MATLAB / C Files
peass.gammatone	GammatoneFilter, GammatoneAnalyzer, GammatoneDelay, GammatoneMixer, GammatoneSynthesizer	Gfb_Filter_new.m, Gfb_Analyzer_process.m, etc.
peass.auditory_model	haircell_transduction, adaptation_loops, generate_internal_representation	haircell.c (MEX), adapt.c (MEX), pemo_internal.m
peass.decomposition	extract_distortion_components, least_squares_decompose_time_varying	extractDistortionComponents.m, LSDecompose_tv.m
peass.metrics	pemo_similarity_metric, calculate_energy_ratios, audio_quality_features	pemo_metric.m, audioQualityFeatures.m
peass.predictor	predict_peass_scores, my_mapping	PEASS_ObjectiveMeasure.m, map2SubjScale.m

Installation

pip install python-peass

Quick Start Examples

1. Perceptual Quality Score Evaluation (Predictor Pipeline)

Evaluate estimated audio files saved on disk:

from peass import predict_peass_scores

original_files = [
    "audio/target_source.wav",
    "audio/interference_1.wav",
    "audio/interference_2.wav"
]
estimate_file = "audio/estimated_target.wav"

scores = predict_peass_scores(original_files, estimate_file)

print(f"Overall Perceptual Score (OPS): {scores['OPS']:.1f}/100")
print(f"Target Preservation Score (TPS): {scores['TPS']:.1f}/100")
print(f"Interference Rejection (IPS):   {scores['IPS']:.1f}/100")
print(f"Artifact-free Score (APS):      {scores['APS']:.1f}/100")

2. Exposing Physical Decompositions and Wav Files

If you wish to obtain the actual separated signal waveforms (True target, Target distortion, Interference, and Artifacts) alongside the predicted scores:

from peass import predict_peass_scores

original_files = ["audio/target.wav", "audio/noise.wav"]
estimate_file = "audio/estimate.wav"

# Setting return_decomposition=True triggers wave synthesis
results = predict_peass_scores(
    original_files,
    estimate_file,
    options={'destDir': './output_directory/'},
    return_decomposition=True
)

# 1. Print Scores
print(f"Overall Perceptual Score: {results['OPS']}")

# 2. Access Filepaths of newly generated wave files on disk
print(f"Decomposed Target saved at: {results['decomposition_files']['true_target']}")

# 3. Read raw numpy arrays directly from memory
target_distortion_array = results['decomposition_arrays']['target_distortion']

3. Running Independent Physical Decomposition (No ML Score Regressor)

You can also run the auditory Gammatone/least-squares decomposition engine by itself to generate isolated WAV files or raw NumPy arrays:

from peass import extract_distortion_components

# In-memory arrays
target_array = np.random.randn(16000, 1)
noise_array = np.random.randn(16000, 1)
estimate_array = target_array + 0.05 * noise_array

# Run subband least-squares decomposer
_, decomposed_arrays = extract_distortion_components(
    src_files=[target_array, noise_array],
    est_file=estimate_array,
    sampling_frequency=16000.0
)

true_target, target_distortion, interference, artifacts = decomposed_arrays

References

1. V. Emiya, E. Vincent, N. Harlander, and V. Hohmann, "Subjective and objective quality assessment of audio source separation", IEEE Transactions on Audio, Speech, and Language Processing, 19(7):2046–2057, 2011.
2. R. Huber and B. Kollmeier, "PEMO-Q — A New Method for Objective Audio Quality Assessment Using a Model of Auditory Perception", IEEE Transactions on Audio, Speech, and Language Processing, 14(6):1902–1911, 2006.
3. V. Hohmann, "Frequency analysis and synthesis using a Gammatone filterbank", Acustica/Acta Acustica, 88(3):433–442, 2002.