Zimtohrli: An Efficient Psychoacoustic Audio Similarity Metric

Fuente: arXiv
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Main Authors: Alakuijala, Jyrki, Bruse, Martin, Boukortt, Sami, Coldenhoff, Jozef Marus, Cernak, Milos
Format: Preprint
Published: 2025
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author Alakuijala, Jyrki
Bruse, Martin
Boukortt, Sami
Coldenhoff, Jozef Marus
Cernak, Milos
author_facet Alakuijala, Jyrki
Bruse, Martin
Boukortt, Sami
Coldenhoff, Jozef Marus
Cernak, Milos
contents This paper introduces Zimtohrli, a novel, full-reference audio similarity metric designed for efficient and perceptually accurate quality assessment. In an era dominated by computationally intensive deep learning models and proprietary legacy standards, there is a pressing need for an interpretable, psychoacoustically-grounded metric that balances performance with practicality. Zimtohrli addresses this gap by combining a 128-bin gammatone filterbank front-end, which models the frequency resolution of the cochlea, with a unique non-linear resonator model that mimics the human eardrum's response to acoustic stimuli. Similarity is computed by comparing perceptually-mapped spectrograms using modified Dynamic Time Warping (DTW) and Neurogram Similarity Index Measure (NSIM) algorithms, which incorporate novel non-linearities to better align with human judgment. Zimtohrli achieves superior performance to the baseline open-source ViSQOL metric, and significantly narrows the performance gap with the latest commercial POLQA metric. It offers a compelling balance of perceptual relevance and computational efficiency, positioning it as a strong alternative for modern audio engineering applications, from codec development to the evaluation of generative audio systems.
format Preprint
id arxiv_https___arxiv_org_abs_2509_26133
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Zimtohrli: An Efficient Psychoacoustic Audio Similarity Metric
Alakuijala, Jyrki
Bruse, Martin
Boukortt, Sami
Coldenhoff, Jozef Marus
Cernak, Milos
Audio and Speech Processing
This paper introduces Zimtohrli, a novel, full-reference audio similarity metric designed for efficient and perceptually accurate quality assessment. In an era dominated by computationally intensive deep learning models and proprietary legacy standards, there is a pressing need for an interpretable, psychoacoustically-grounded metric that balances performance with practicality. Zimtohrli addresses this gap by combining a 128-bin gammatone filterbank front-end, which models the frequency resolution of the cochlea, with a unique non-linear resonator model that mimics the human eardrum's response to acoustic stimuli. Similarity is computed by comparing perceptually-mapped spectrograms using modified Dynamic Time Warping (DTW) and Neurogram Similarity Index Measure (NSIM) algorithms, which incorporate novel non-linearities to better align with human judgment. Zimtohrli achieves superior performance to the baseline open-source ViSQOL metric, and significantly narrows the performance gap with the latest commercial POLQA metric. It offers a compelling balance of perceptual relevance and computational efficiency, positioning it as a strong alternative for modern audio engineering applications, from codec development to the evaluation of generative audio systems.
title Zimtohrli: An Efficient Psychoacoustic Audio Similarity Metric
topic Audio and Speech Processing
url https://arxiv.org/abs/2509.26133