Acoustic Complexity Index (ACI)

AUS-ASC-CON-ACI General Moderate confidence

Benchmark Value

No specific value — see range

Range: 1802 to 2227 index

Optimal Range: 1802 to 2227

Direction: Higher is desirable ↑

Form: OptimalRange

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.

Evidence & Context

Example 1: ACI = 1802... Example 4: ACI = 2227

Metric Definition:

Computed as the amplitude difference between successive Fourier windows for each frequency band.

Benchmark Definition:

This benchmark represents the optimal range of acoustic complexity index values for high-health Australian soundscapes using the 'acousticecology' R package scaling during summer.

Justification:

Provides real-world recording benchmarks for high-activity Australian biophony.

Sources (1)

Preview of Acoustic indices for biodiversity assessments: Analyses of bias based on simulated bird assemblages and recommendations for field surveys | Request PDF - ResearchGate

Acoustic indices for biodiversity assessments: Analyses of bias based on simulated bird assemblages and recommendations for field surveys | Request PDF - ResearchGate GreyLiterature

Acoustic Complexity Index: A Simple Overview (with examples) - YouTube, accessed May 14, 2026

Supporting Sources (43)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Acoustic restoration: Using soundscapes to benchmark and fasttrack recovery of ecological communities - ResearchGate, accessed May 14, 2026,

(PDF) Acoustic restoration: Using soundscapes to benchmark and fasttrack recovery of ecological communities - ResearchGate, accessed May 14, 2026,

Contextual Support Direct Evidence GreyLiterature

(PDF) Acoustic restoration: Using soundscapes to benchmark and fast‐track recovery of ecological communities - ResearchGate, accessed May 14, 2026

Preview of A new methodology to infer the singing activity of an avian community: The Acoustic Complexity Index (ACI) | Request PDF - ResearchGate

A new methodology to infer the singing activity of an avian community: The Acoustic Complexity Index (ACI) | Request PDF - ResearchGate

Direct Evidence Methodology Source GreyLiterature

A new methodology to infer the singing activity of an avian community: The Acoustic Complexity Index (ACI) | Request PDF - ResearchGate

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A REPORT ON A COMMUNITY PARTNERSHIP IN ECO-ACOUSTIC MONITORING IN MOUNT WORTH STATE PARK, VICTORIA, accessed May 14, 2026,

Contextual Support Direct Evidence Regulatory Framework Journal

A REPORT ON A COMMUNITY PARTNERSHIP IN ECO-ACOUSTIC MONITORING IN MOUNT WORTH STATE PARK, VICTORIA, accessed May 14, 2026

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ABSTRACTS - Squarespace, accessed May 14, 2026,

Contextual Support Direct Evidence Journal

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Preview of Acoustic Complexity Index → Term - Pollution → Sustainability Directory

Acoustic Complexity Index → Term - Pollution → Sustainability Directory

Contextual Support Direct Evidence GreyLiterature

Rapid assessment of avian species richness and abundance using acoustic indices, accessed May 14, 2026

Preview of Acoustic indices as proxies for biodiversity: a meta‐analysis - PMC - PubMed Central, accessed July 22, 2025,

Acoustic indices as proxies for biodiversity: a meta‐analysis - PMC - PubMed Central, accessed July 22, 2025,

Contextual Support Direct Evidence Journal

Acoustic Indices for Biodiversity Assessment and Landscape Investigation, accessed July 12, 2025

Preview of Acoustic indices as proxies for biodiversity: a meta‐analysis | Request PDF - ResearchGate

Acoustic indices as proxies for biodiversity: a meta‐analysis | Request PDF - ResearchGate

Contextual Support Direct Evidence GreyLiterature

The Application of Ecological Acoustic Indices to Identify The Dominant Sound Components in Soundscape Recording | Request PDF - ResearchGate, accessed May 14, 2026

Preview of Acoustic indices as proxies for biodiversity: a metaanalysis - PMC, accessed May 14, 2026,

Acoustic indices as proxies for biodiversity: a metaanalysis - PMC, accessed May 14, 2026,

Contextual Support Direct Evidence GreyLiterature

Acoustic indices as proxies for biodiversity: a meta‐analysis | Request PDF - ResearchGate, accessed May 14, 2026

Preview of Acoustic indices for biodiversity assessments: Analyses of bias based on simulated bird assemblages and recommendations for field surveys | Request PDF - ResearchGate, accessed May 14, 2026,

Acoustic indices for biodiversity assessments: Analyses of bias based on simulated bird assemblages and recommendations for field surveys | Request PDF - ResearchGate, accessed May 14, 2026,

Contextual Support Direct Evidence Methodology Source GreyLiterature

Acoustic indices for biodiversity assessments: Analyses of bias based on simulated bird assemblages and recommendations for field surveys | Request PDF - ResearchGate, accessed May 14, 2026

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Acoustic patterns at the Samford Ecological Research Facility in South East Queensland, Australia: The Peri-Urban SuperSite of the Terrestrial Ecosystem Research Network | Request PDF - ResearchGate, accessed July 25, 2025,

Contextual Support Direct Evidence Journal

Acoustic patterns at the Samford Ecological Research Facility in South East Queensland, Australia: The Peri-Urban SuperSite of the Terrestrial Ecosystem Research Network | Request PDF - ResearchGate, accessed May 14, 2026

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Acoustic Sensor-Based Soundscape Analysis and Acoustic Assessment of Bird Species Richness in Shennongjia National Park, China - PMC, accessed May 14, 2026,

Contextual Support Direct Evidence Journal

Acoustic Sensor-Based Soundscape Analysis and Acoustic Assessment of Bird Species Richness in Shennongjia National Park, China - PMC, accessed May 14, 2026

Preview of Advancements in preprocessing, detection and classification

Advancements in preprocessing, detection and classification

Contextual Support Direct Evidence GreyLiterature

Australian Acoustic Observatory (A2O), 2024. Continental-scale acoustic sensor network. QUT, Brisbane.

Preview of Alcocer, I., et al., 2022. Acoustic indices as proxies for biodiversity: a meta-analysis. Biological reviews of the Cambridge Philosophical Society, 97(%).

Alcocer, I., et al., 2022. Acoustic indices as proxies for biodiversity: a meta-analysis. Biological reviews of the Cambridge Philosophical Society, 97(%).

Contextual Support Direct Evidence Journal

Acoustic indices as proxies for biodiversity: a meta’analysis - PMC

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Australian Acoustic Observatory | A2O – Australian Acoustic ..., accessed July 18, 2025

Contextual Support Direct Evidence GreyLiterature

Boelman, N. T., et al., 2007. Multi-trophic invasion resistance in Hawaii: bioacoustics, field surveys, and airborne remote sensing. Ecological Applications, 17(8).

Preview of Bradfer-Lawrence, T., et al., 2019. Guidelines for the use of acoustic indices in environmental research. Methods in Ecology and Evolution, 10(10).

Bradfer-Lawrence, T., et al., 2019. Guidelines for the use of acoustic indices in environmental research. Methods in Ecology and Evolution, 10(10).

Contextual Support Direct Evidence Journal

Bradfer-Lawrence, T., et al., 2019. Guidelines for the use of acoustic indices in environmental research. Methods in Ecology and Evolution, 10(10).

Preview of Buxton, R. T., et al., 2018. Efficacy of extracting indices from large-scale acoustic recordings to monitor biodiversity. Conservation Biology, 32(%).

Buxton, R. T., et al., 2018. Efficacy of extracting indices from large-scale acoustic recordings to monitor biodiversity. Conservation Biology, 32(%).

Direct Evidence Methodology Source Journal

Buxton, R. T., et al., 2018. Efficacy of extracting indices from large-scale acoustic recordings to monitor biodiversity. Conservation Biology, 32(%).

Preview of Do acoustic indices correlate with bird diversity? Insights from two biodiverse regions in Yunnan Province, south China | Request PDF - ResearchGate, accessed May 14, 2026,

Do acoustic indices correlate with bird diversity? Insights from two biodiverse regions in Yunnan Province, south China | Request PDF - ResearchGate, accessed May 14, 2026,

Contextual Support Direct Evidence GreyLiterature

Do acoustic indices correlate with bird diversity? Insights from two biodiverse regions in Yunnan Province, south China | Request PDF - ResearchGate, accessed May 14, 2026

Preview of Farina, A., 2025. The acoustic complexity index (ACI): theoretical foundations, applied perspectives, and semantics.

Farina, A., 2025. The acoustic complexity index (ACI): theoretical foundations, applied perspectives, and semantics.

Direct Evidence Methodology Source Journal

Farina, A., 2025. The acoustic complexity index (ACI): theoretical foundations, applied perspectives, and semantics.

Preview of Full article: The relationship between the Acoustic Complexity Index and avian species richness and diversity: a review - Taylor & Francis Online, accessed July 22, 2025,

Full article: The relationship between the Acoustic Complexity Index and avian species richness and diversity: a review - Taylor & Francis Online, accessed July 22, 2025,

Contextual Support Direct Evidence

Acoustic Complexity of vocal fish communities: a field and controlled validation - PMC, accessed May 14, 2026

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Grassland bird community and acoustic complexity appear unaffected by proximity to a wind energy facility in the Nebraska Sandhills

Contextual Support GreyLiterature

Grassland bird community and acoustic complexity appear unaffected by proximity to a wind energy facility in the Nebraska Sandhills

Preview of Indraswari, K., et al., 2020. Assessing the value of acoustic indices to distinguish species and quantify activity: A case study using frogs. Freshwater Biology, 65.

Indraswari, K., et al., 2020. Assessing the value of acoustic indices to distinguish species and quantify activity: A case study using frogs. Freshwater Biology, 65.

Contextual Support Direct Evidence Journal

Indraswari, K., et al., 2020. Assessing the value of acoustic indices to distinguish species and quantify activity: A case study using frogs. Freshwater Biology, 65.

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Linke, S., et al., 2020. Diurnal variation in freshwater ecoacoustics: Implications for site-level sampling design. Freshwater Biology, 65(3).

Contextual Support Direct Evidence Journal

Linke, S., et al., 2020. Diurnal variation in freshwater ecoacoustics: Implications for site-level sampling design. Freshwater Biology, 65(3).

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Mapping ecoacoustic hot spots and moments of biodiversity to inform conservation and urban planning - ResearchGate, accessed May 14, 2026,

Contextual Support Direct Evidence GreyLiterature

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McGrann, M. C., et al., 2022. Using an acoustic complexity index to help monitor climate change effects on avian diversity. Ecological Indicators, 142.

Contextual Support Direct Evidence Journal

McGrann, M. C., et al., 2022. Using an acoustic complexity index to help monitor climate change effects on avian diversity. Ecological Indicators, 142.

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Multi-Index Ecoacoustics Analysis for Terrestrial Soundscapes: A New Semi-Automated Approach Using Time-Series Motif Discovery and Random Forest Classification - Frontiers

Direct Evidence Journal

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Museums Victoria, 2019. Otway Bioscan: Bio-acoustic surveys of birds across burnt and unburnt sites.

Contextual Support Direct Evidence GreyLiterature

Museums Victoria, 2019. Otway Bioscan: Bio-acoustic surveys of birds across burnt and unburnt sites.

Preview of Pieretti, N., et al., 2011. A new methodology to infer the singing activity of an avian community: The Acoustic Complexity Index (ACI). Ecological Indicators, 11(%).

Pieretti, N., et al., 2011. A new methodology to infer the singing activity of an avian community: The Acoustic Complexity Index (ACI). Ecological Indicators, 11(%).

Direct Evidence Methodology Source Journal

Pieretti, N., et al., 2011. A new methodology to infer the singing activity of an avian community: The Acoustic Complexity Index (ACI). Ecological Indicators, 11(%).

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Quantifying the Soundscape: How Filters Change Acoustic Indices - Furman University Scholar Exchange, accessed July 24, 2025,

Contextual Support Direct Evidence Methodology Source

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Contextual Support Direct Evidence Methodology Source GreyLiterature

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Quinn, C. A., et al., 2023. Investigations of ecoacoustic biodiversity characterized with acoustic indices. PhD Thesis, Northern Arizona University.

Contextual Support Direct Evidence GreyLiterature

Quinn, C. A., et al., 2023. Investigations of ecoacoustic biodiversity characterized with acoustic indices. PhD Thesis, Northern Arizona University.

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Roe, P., et al. (2021). The Australian Acoustic Observatory. Methods in Ecology and Evolution, 12(10), 1802-1808. DOI: 10.1111/2041-210X.13660

Contextual Support Direct Evidence Journal

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Scarpelli, M., 2021. Identifying the dominant sound components in soundscape recordings. Frontiers in Ecology and Evolution.

Contextual Support Direct Evidence Journal

Scarpelli, M., 2021. Identifying the dominant sound components in soundscape recordings. Frontiers in Ecology and Evolution.

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Soundscape-based evaluation of small-scale forest management interventions

Irrelevant Journal

Soundscape-based evaluation of small-scale forest management interventions

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Stol, J. and Kitchen, M., 2020. Tumbarumba Wet Eucalypt Acoustic Data Collection - A2O Project. TERN Ecosystem Processes.

Contextual Support Direct Evidence Government

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Preview of Tasmanian Land Conservancy, 2020. Five Rivers Reserve - Site 70 information. Australian Acoustic Observatory.

Tasmanian Land Conservancy, 2020. Five Rivers Reserve - Site 70 information. Australian Acoustic Observatory.

Contextual Support Direct Evidence Journal

Five Rivers - A2O | Sites | Australian Acoustic Observatory

Preview of Temporal and spatial variability of ACI values for sensors 1 -8,... - ResearchGate, accessed May 14, 2026,

Temporal and spatial variability of ACI values for sensors 1 -8,... - ResearchGate, accessed May 14, 2026,

Contextual Support Direct Evidence GreyLiterature

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Preview of The acoustic complexity index (ACI): theoretical foundations, applied perspectives and semantics - ResearchGate

The acoustic complexity index (ACI): theoretical foundations, applied perspectives and semantics - ResearchGate

Contextual Support Direct Evidence Methodology Source GreyLiterature

The acoustic complexity index (ACI): theoretical foundations, applied perspectives and semantics - ResearchGate, accessed May 14, 2026

Preview of The sound of restored soil: Measuring soil biodiversity in a forest restoration chronosequence with ecoacoustics | bioRxiv, accessed May 14, 2026,

The sound of restored soil: Measuring soil biodiversity in a forest restoration chronosequence with ecoacoustics | bioRxiv, accessed May 14, 2026,

Contextual Support Direct Evidence GreyLiterature

The sound of restored soil: Measuring soil biodiversity in a forest restoration chronosequence with ecoacoustics | bioRxiv, accessed May 14, 2026

Preview of Tumbarumba Wet Eucalypt Acoustic Data Collection - A2O Project, accessed May 14, 2026,

Tumbarumba Wet Eucalypt Acoustic Data Collection - A2O Project, accessed May 14, 2026,

Contextual Support Direct Evidence

Tumbarumba Wet Eucalypt Acoustic Data Collection - A2O Project, accessed May 14, 2026

Preview of Ulloa, N., et al., 2021. scikit-maad: An open-source and modular toolbox for quantitative soundscape analysis in Python. Methods in Ecology and Evolution, 12(12).

Ulloa, N., et al., 2021. scikit-maad: An open-source and modular toolbox for quantitative soundscape analysis in Python. Methods in Ecology and Evolution, 12(12).

Contextual Support Direct Evidence GreyLiterature

Ulloa, N., et al., 2021. scikit-maad: An open-source and modular toolbox for quantitative soundscape analysis in Python. Methods in Ecology and Evolution, 12(12).

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Contextual Support Direct Evidence GreyLiterature

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WFAE - World Forum for Acoustic Ecology | A E World Map, accessed May 14, 2026,

Contextual Support Direct Evidence Irrelevant

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Znidersic, E. and Watson, D. M., 2022. Acoustic restoration: Using soundscapes to benchmark and fast-track recovery of ecological communities. Ecology Letters, 25.

Contextual Support Direct Evidence Journal

A new methodology to infer the singing activity of an avian community: The Acoustic Complexity Index (ACI) | Request PDF - ResearchGate, accessed May 14, 2026