{
  "abstract": "Acoustic recording can follow decomposition non-destructively, but which acoustic measures carry process information is largely untested. In a proof-of-concept experiment, four nonlinear complexity measures and six conventional ecoacoustic indices were compared in eight octave bands, using 150 recordings from five buckets of one vermicompost-hay batch during one mesophilic heating-cooling cycle. Internal temperature served as a proxy for the system state. Because smooth trajectories can agree by chance, a four-parameter temperature model with a heating-cooling term was evaluated on held-out buckets and against 100000 surrogate temperature courses with the same values and smoothness but randomised timing. For the nonlinear measures, the model predicted held-out buckets with a median skill of 0.48, better than a linear time trend, a time model with the same heating-cooling break and the surrogates (p = 0.00003). The conventional indices reached 0.12 and were not distinguishable from the surrogates (p = 0.21). The group difference exceeded that of the surrogates (p = 0.0002). At equal temperature, the nonlinear measures differed between heating and cooling. Their skill was highest at 128–256Hz (median held-out skill 0.70). The temperature model nearly matched a data-driven benchmark without temperature for the nonlinear measures (0.50), but not for the conventional indices (0.18). In-sample fits overstated predictive skill (median R2 0.81 and 0.36), so held-out prediction against surrogate covariates provides a practical test for acoustic indicators in single experiments. Since the buckets replicate the measurement, not the process, replication across batches and cycles is needed.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "name": "Jakob Eisenhauer"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7mzv024wwbh4d.bib",
  "cited_by": 0,
  "doi": "10.31223/x5123j",
  "fulltext_url": null,
  "id": "7mzv024wwbh4d",
  "issns": [],
  "landing_url": "https://eartharxiv.org/repository/view/15995/",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/legalcode",
  "metadata_licence": null,
  "native_subjects": [
    [
      "bepress",
      "Applied Statistics"
    ],
    [
      "bepress",
      "Dynamic Systems"
    ],
    [
      "bepress",
      "Environmental Indicators and Impact Assessment"
    ],
    [
      "bepress",
      "Environmental Microbiology and Microbial Ecology Life Sciences"
    ],
    [
      "bepress",
      "Environmental Monitoring"
    ],
    [
      "bepress",
      "Lempel-Ziv complexity"
    ],
    [
      "bepress",
      "Non-linear Dynamics"
    ],
    [
      "bepress",
      "Physical and Environmental Geography"
    ],
    [
      "bepress",
      "Soil Science"
    ],
    [
      "bepress",
      "acoustic complexity index"
    ],
    [
      "bepress",
      "bioacoustics"
    ],
    [
      "bepress",
      "complexity measures"
    ],
    [
      "bepress",
      "composting"
    ],
    [
      "bepress",
      "cross-validation"
    ],
    [
      "bepress",
      "decomposition"
    ],
    [
      "bepress",
      "ecoacoustic indices"
    ],
    [
      "bepress",
      "entropy measures"
    ],
    [
      "bepress",
      "held-out prediction"
    ],
    [
      "bepress",
      "indicator development"
    ],
    [
      "bepress",
      "non-invasive monitoring"
    ],
    [
      "bepress",
      "nonlinear time series"
    ],
    [
      "bepress",
      "organic matter decomposition"
    ],
    [
      "bepress",
      "passive acoustic monitoring"
    ],
    [
      "bepress",
      "permutation entropy"
    ],
    [
      "bepress",
      "proof of concept"
    ],
    [
      "bepress",
      "self-heating"
    ],
    [
      "bepress",
      "soil acoustics"
    ],
    [
      "bepress",
      "soil carbon"
    ],
    [
      "bepress",
      "soil ecoacoustics"
    ],
    [
      "bepress",
      "soundscape ecology"
    ],
    [
      "bepress",
      "surrogate data"
    ],
    [
      "bepress",
      "vermicompost"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://eartharxiv.org/repository/object/15995/download/27680/",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7mzv024wwbh4d.ris",
  "sources": [
    {
      "first_seen": "2026-11-08T12:20:49Z",
      "native_id": "15995",
      "source": "eartharxiv",
      "url": "https://eartharxiv.org/repository/view/15995/"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "bepress:Environmental Monitoring",
      "subfield": "environmental-science"
    },
    {
      "field": "earth",
      "origin": "bepress:Soil Science",
      "subfield": "hydrology-soils"
    },
    {
      "field": "mathematics",
      "origin": "bepress:Applied Statistics",
      "subfield": "statistics"
    }
  ],
  "title": "Hearing the heat: a proof-of-concept study of nonlinear sound measures for distinguishing phases of rapid organic decomposition",
  "title_text": "Hearing the heat: a proof-of-concept study of nonlinear sound measures for distinguishing phases of rapid organic decomposition",
  "type": "preprint",
  "updated_at": "2026-11-08T12:20:49Z",
  "url": "https://research.draconitic.com/paper/7mzv024wwbh4d",
  "venue": "EarthArXiv",
  "versions": []
}