Investigation of infrasound noise background at M\'atra Gravitational and Geophysical Laboratory (MGGL)

Edit Fenyvesi; J\'ozsef Moln\'ar; S\'andor Czell\'ar

arxiv: 1907.00396 · v1 · pith:YW562D2Knew · submitted 2019-06-30 · 🌌 astro-ph.IM

Investigation of infrasound noise background at M\'atra Gravitational and Geophysical Laboratory (MGGL)

Edit Fenyvesi , J\'ozsef Moln\'ar , S\'andor Czell\'ar This is my paper

Pith reviewed 2026-05-25 12:21 UTC · model grok-4.3

classification 🌌 astro-ph.IM

keywords infrasoundtransientsHaar transformNewtonian noisegravitational wave detectorssite characterizationmine ventilationbackground noise

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The pith

A discrete Haar transform algorithm detects transients in infrasound signals recorded at a mine laboratory.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper investigates infrasound noise at a subterranean laboratory intended for gravitational wave detector development. Mining activities introduce sudden transients and continuous background noise that can affect measurements of gravity-gradient noise below 20 Hz. The authors present an algorithm based on the discrete Haar transform to locate these transients in the signal. Removing the identified transients reduces variation in the noise spectra. On-off tests of operating machinery show that the ventilation system is the main source of the continuous noise.

Core claim

The paper claims that a discrete Haar transform algorithm identifies transients in the infrasound signal, and that their removal decreases variation in the noise spectra. Systematic on-off experiments on mine machinery establish the ventilation system as the dominant contributor to the continuous background noise.

What carries the argument

Discrete Haar transform algorithm for detecting transients in the infrasound signal

If this is right

Eliminating transients yields noise spectra with lower variation for more reliable background characterization.
The ventilation system is established as the primary source of continuous noise at the site.
Targeted mitigation of ventilation noise becomes feasible for reducing Newtonian noise in subterranean gravitational-wave detectors.
Site characterization measurements gain accuracy by accounting for mining-induced transients.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

The transient detection method could extend to seismic data collected at the same or similar underground sites.
Engineering changes to the ventilation system might lower overall noise levels without affecting other mine operations.
Repeated application of the algorithm across multiple sites could help rank candidate locations for third-generation detectors.

Load-bearing premise

The on-off experiments on individual machines isolate their noise contributions without interference from other sources or environmental variations.

What would settle it

If the Haar transform algorithm leaves detectable transients in the data or if disabling the ventilation system produces no measurable drop in the continuous noise level.

Figures

Figures reproduced from arXiv: 1907.00396 by Edit Fenyvesi, J\'ozsef Moln\'ar, S\'andor Czell\'ar.

**Figure 1.** Figure 1: The red lines show the PASD curves computed from measurement data containing transients, while the blue [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗

**Figure 2.** Figure 2: Results of noise controlling experiment. The MGGL-median curve corresponds to the measurement campaig [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗

**Figure 3.** Figure 3: The orange line indicates the lowest noise level measured at MGGL, when the ventilation system was turned [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗

read the original abstract

Infrasonic and seismic waves are supposed to be the main contributors to the gravity-gradient noise (Newtonian noise) of the third generation subterranean gravitational-wave detectors. This noise will limit the sensitivity of the instrument at frequencies below 20 Hz. Investigation of its origin and the possible methods of mitigation have top priority during the designing period of the detectors. Therefore long-term site characterizing measurements are needed at several subterranean sites. However, at some sites, mining activities can occur. These activities can cause sudden changes (transients) in the measured signal, and increase the continuous background noise, too. We have developed a new algorithm based on discrete Haar transform to find these transients in the infrasound signal. We found that eliminating the transients decreases the variation of the noise spectra, and hence results a more accurate characterization of the background noise. We also carried out experiments for controlling the continuous noise. Machines operating at the mine was turned on and off systematically in order to see their effect on the noise spectra. These experiments showed that the main contributor of the continuous noise is the ventilation system of the mine.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This is a site survey paper that applies discrete Haar transform to catch infrasound transients and uses on-off machine tests to identify ventilation as the main continuous noise source at MGGL, but the isolation of that source looks vulnerable to mine-specific confounders.

read the letter

The main takeaway is that the authors measured infrasound at an active mine, built a Haar-transform routine to flag transients, showed that removing them tightens the noise spectra, and ran on-off tests that led them to blame the ventilation system for most of the steady background. That is the concrete result a reader gets from the abstract and the described experiments. The work sits inside the existing program of Newtonian-noise site surveys for underground gravitational-wave detectors, so the relevance is clear even if the advance is incremental. They chose a standard wavelet for transient detection and actually ran controlled switches on real equipment, which is more than many site papers manage. The transient-removal step is presented as improving spectral stability, and that claim is at least testable from the data they collected. The on-off experiments are the part that needs scrutiny. Shutting down ventilation in a mine changes airflow, pressure, and possibly other coupled sources at the same time, and the description gives no sign of repeated interleaved trials, independent monitoring of barometric or temperature drift, or error bars on the spectral differences. Without those, it is hard to treat the ventilation attribution as cleanly demonstrated rather than suggestive. The paper is aimed at groups doing third-generation detector site work who need practical numbers from a mine environment. A reader already tracking Newtonian noise at subterranean sites would get usable reference data and one concrete algorithm example, but not a new general framework. It deserves peer review because the measurements address a stated priority for detector design and the experimental approach is the sort that referees can evaluate for controls and statistics once the full methods and data are in front of them.

Referee Report

2 major / 2 minor

Summary. The manuscript reports infrasound measurements at the Mátra Gravitational and Geophysical Laboratory (MGGL) in support of site characterization for third-generation gravitational-wave detectors. It introduces a discrete Haar transform algorithm to identify transients in the infrasound time series, demonstrates that transient removal reduces spectral variability, and presents on-off experiments on mine machinery that identify the ventilation system as the dominant source of continuous noise background.

Significance. Site-specific identification of Newtonian-noise contributors is relevant for subterranean GW detector design. If the on-off isolation and transient algorithm are robust, the results could directly inform mitigation priorities at mining-adjacent sites; the empirical data add to the limited body of underground infrasound characterizations.

major comments (2)

[on-off experiments] On-off experiments section: the central claim that ventilation is the main continuous-noise contributor rests on systematic machine on-off tests, yet the manuscript provides no description of repeated interleaved trials, statistical significance testing or error propagation on the observed spectral differences, or independent monitoring of confounding variables (airflow, pressure, temperature) that are expected to change when ventilation is altered in an underground environment.
[algorithm] Transient-detection algorithm section: the discrete Haar transform method is presented as newly developed for this application, but the text does not supply quantitative validation (e.g., detection efficiency, false-positive rate on injected transients or comparison against standard wavelet or matched-filter approaches) needed to establish that the algorithm improves upon existing transient-finding techniques.

minor comments (2)

[figures] Figure captions and axis labels should explicitly state the frequency range, averaging method, and whether spectra are shown before or after transient removal.
[abstract and results] The abstract states that transients were eliminated to obtain a 'more accurate characterization,' but the main text should quantify the reduction in spectral variance (e.g., standard deviation across epochs) rather than stating it qualitatively.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments on our manuscript. We address each major comment below, indicating planned revisions where appropriate to strengthen the presentation of the on-off experiments and the transient-detection algorithm.

read point-by-point responses

Referee: On-off experiments section: the central claim that ventilation is the main continuous-noise contributor rests on systematic machine on-off tests, yet the manuscript provides no description of repeated interleaved trials, statistical significance testing or error propagation on the observed spectral differences, or independent monitoring of confounding variables (airflow, pressure, temperature) that are expected to change when ventilation is altered in an underground environment.

Authors: We agree that the on-off section would benefit from greater detail on experimental design and limitations. The tests consisted of systematic, sequential on-off switching of the ventilation system and other mine machinery while recording infrasound spectra; however, the manuscript does not describe repeated interleaved trials, formal statistical tests, error propagation, or independent monitoring of airflow, pressure or temperature. Operational constraints at the underground site prevented additional instrumentation and multiple interleaved runs. We will revise the section to describe the exact sequence performed, explicitly note the absence of statistical analysis and confounding-variable monitoring, and qualify the conclusion that ventilation dominates the continuous background accordingly. revision: partial
Referee: Transient-detection algorithm section: the discrete Haar transform method is presented as newly developed for this application, but the text does not supply quantitative validation (e.g., detection efficiency, false-positive rate on injected transients or comparison against standard wavelet or matched-filter approaches) needed to establish that the algorithm improves upon existing transient-finding techniques.

Authors: The manuscript introduces the discrete Haar transform as a practical tool for identifying transients in the MGGL infrasound records and demonstrates its utility through the observed reduction in spectral variability after removal. We did not include quantitative performance metrics such as detection efficiency, false-positive rates on injected signals, or direct comparisons to wavelets or matched filters. We will revise the algorithm section to add a short validation subsection that applies the method to synthetic transients with known properties and reports basic detection statistics, while clarifying that the primary contribution is the application to site-characterization data rather than a comprehensive benchmark against other techniques. revision: yes

Circularity Check

0 steps flagged

No significant circularity in empirical measurements and algorithm application

full rationale

The paper reports direct site measurements of infrasound, application of a discrete Haar transform algorithm to detect transients, and on-off experiments isolating machine contributions. No load-bearing derivations, equations, or predictions are described that reduce by construction to fitted inputs or self-definitions. No self-citation chains or uniqueness theorems are invoked. The central claims rest on experimental data collection and processing rather than any circular reduction, consistent with the paper being an observational characterization study.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the applicability of the discrete Haar transform for transient detection and the validity of on-off isolation in experiments, with no free parameters, invented entities, or additional axioms beyond standard signal-processing assumptions.

axioms (1)

domain assumption The discrete Haar transform can be used to detect transients in infrasound time series data.
Basis for the algorithm described in the abstract.

pith-pipeline@v0.9.0 · 5739 in / 1138 out tokens · 33152 ms · 2026-05-25T12:21:30.473125+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

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B. P. Abbott et al. (LIGO Scientiﬁc Collaboration and Virgo Collaboration). Observation of Gravitational Waves from a Binary Black Hole Merger, Phys. Rev. Lett., 2016, 116(6), 061102, doi:10.1103/PhysRevLett.116.061102

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work page doi:10.3847/2041- 2017

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B. P. Abbott et al. (LIGO Scientiﬁc Collaboration and Virgo Collaboration), GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence. Phys. Rev. Lett. , 2017, 119(14), 141101, doi:10.1103/PhysRevLett.119.141101

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Beker, J

M. Beker, J. van den Brand, D. S. Rabeling, Subterranean ground motion studies for the Einstein Telescope. Classical and Quantum Gravity , 2015, 32, doi:10.1088/0264-9381/32/2/025002

work page doi:10.1088/0264-9381/32/2/025002 2015

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G. G. Barnaföldi et al., First report of long term measurements of the MGGL laboratory in the Mátra mountain range. Class. Quant. Grav., 2017, 34(11), 114001, doi:10.1088/1361-6382/aa69e3

work page doi:10.1088/1361-6382/aa69e3 2017

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Ván et al., Long term measurements from the Mátra Gravitational and Geophysical Laboratory

P. Ván et al., Long term measurements from the Mátra Gravitational and Geophysical Laboratory. 2018, arXiv:1811.05198

work page arXiv 2018

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J. R. Bowman, G. E. Baker, M. Bahavar, Ambient infrasound noise. Geophysical Research Letters, 2005, 32(9), L09803, doi:10.1029/2005GL022486

work page doi:10.1029/2005gl022486 2005

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Classical and Quantum Gravity , 2008, 27(22), 225011, doi:10.1088/0264-9381/27/22/225011

J.Harms et al., Characterization of the seismic environment at the Sanford Underground Laboratory, South Dakota. Classical and Quantum Gravity , 2008, 27(22), 225011, doi:10.1088/0264-9381/27/22/225011

work page doi:10.1088/0264-9381/27/22/225011 2008

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C. Leys, C. Ley and O. Klein, P. Bernard and L. Licata, Detecting outliers: Do not use standard deviation around the mean, use absolute deviation around the median. Journal of Experimental Social Psychology , 2013, 49(4), 764 - 766, doi:10.1016/j.jesp.2013.03.013. 7

work page doi:10.1016/j.jesp.2013.03.013 2013