Acoustic Complexity Index (ACI)

AUS-TSR-FOR-ACI General Low confidence

Benchmark Value

No specific value — see range
Range: 1800 to 2200 index
Optimal Range: 1800 to 2200
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

a scientifically defensible, low-confidence indicative benchmark range of 1800–2200 has been inferred.

Metric Definition:

The Acoustic Complexity Index (ACI) was formulated to quantify the complexity of biotic sounds by measuring the temporal variability of sound intensities within a recording.

Benchmark Definition:

This benchmark represents an indicative range of Acoustic Complexity Index values reflecting the best available condition for production forestry in Australian tropical and subtropical rainforests, based on protected old-growth forest analogues adjusted for selective logging impacts.

Justification:

It is derived by using the TERN Robson Creek SuperSite—a protected, old-growth rainforest—as the analogue for the biome's 'potential ecological ceiling' and modulating this high reference state downwards to account for the known ecological impacts of best-practice selective logging on forest structure and faunal composition.

Sources (1)

Preview of TERN Data Discovery Portal, accessed July 18, 2025
TERN Data Discovery Portal, accessed July 18, 2025

TERN Data Discovery Portal

View Source

Supporting Sources (21)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Changes in the acoustic structure of Australian bird communities along a habitat complexity gradient - ResearchGate
(PDF) Changes in the acoustic structure of Australian bird communities along a habitat complexity gradient - ResearchGate
Contextual Support GreyLiterature

soe2021-overview.pdf - Australia state of the environment 2021, accessed July 19, 2025

View Source
Preview of (PDF) Sustainable harvesting of tropical rainforests: Reply to Keto, Scott and Olsen, accessed July 20, 2025
(PDF) Sustainable harvesting of tropical rainforests: Reply to Keto, Scott and Olsen, accessed July 20, 2025
Contextual Support GreyLiterature

Soundscapes predict species occurrence in tropical forests - ResearchGate, accessed July 20, 2025

View Source
Preview of Acoustic Complexity Index → Term - Pollution → Sustainability Directory
Acoustic Complexity Index → Term - Pollution → Sustainability Directory
Contextual Support GreyLiterature

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

View Source
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 Journal

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

View Source
Preview of Acoustic indices as rapid indicators of avian diversity in different land-use types in an Indian biodiversity hotspot, accessed July 18, 2025
Acoustic indices as rapid indicators of avian diversity in different land-use types in an Indian biodiversity hotspot, accessed July 18, 2025
Direct Evidence GreyLiterature

Acoustic indices as rapid indicators of avian diversity in different land-use types in an Indian biodiversity hotspot, accessed July 20, 2025

View Source
Preview of 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,
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,
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

View Source
Preview of Assessing the Avian Soundscapes Using Acoustic Indices and How They Relate to Arthropod Damage in Collard Green Fields - WUR eDepot, accessed July 22, 2025,
Assessing the Avian Soundscapes Using Acoustic Indices and How They Relate to Arthropod Damage in Collard Green Fields - WUR eDepot, accessed July 22, 2025,
Contextual Support Journal

Savanna fire regimes and biodiversity impacts in northern Australia - Resilient Landscapes Hub, accessed July 24, 2025

View Source
Preview of Australia's first rainforest research 'Supersite' opens for business - CSIROpedia, accessed July 20, 2025
Australia's first rainforest research 'Supersite' opens for business - CSIROpedia, accessed July 20, 2025
Contextual Support Government

Australian Forest and Wood Innovations, accessed July 20, 2025

View Source
Preview of Changes in the acoustic structure of Australian bird ... - Blumstein Lab, accessed July 18, 2025
Changes in the acoustic structure of Australian bird ... - Blumstein Lab, accessed July 18, 2025
Direct Evidence Journal

Changes in the acoustic structure of Australian bird ... - Blumstein Lab, accessed July 20, 2025

View Source
Preview of Ecoacoustics with Machine Learning | University of Tasmania, accessed July 18, 2025,
Ecoacoustics with Machine Learning | University of Tasmania, accessed July 18, 2025,
Contextual Support Government

James Montgomery | Funded projects | University of Tasmania, accessed July 12, 2025

View Source
Preview of Effectiveness of acoustic indices as indicators of vertebrate biodiversity, accessed July 18, 2025
Effectiveness of acoustic indices as indicators of vertebrate biodiversity, accessed July 18, 2025
Contextual Support Journal

Lowland Rainforest of Subtropical Australia ecological community - listing advice, accessed July 19, 2025

View Source
Preview of Estimating ecoacoustic activity in the Amazon rainforest through Information Theory quantifiers - Our journal portfolio - PLOS
Estimating ecoacoustic activity in the Amazon rainforest through Information Theory quantifiers - Our journal portfolio - PLOS
Contextual Support Journal

Effectiveness of acoustic indices as indicators of vertebrate biodiversity, accessed July 19, 2025

View Source
Preview of Forest & Wood Products Australia (FWPA), accessed July 20, 2025
Forest & Wood Products Australia (FWPA), accessed July 20, 2025
Contextual Support GreyLiterature

Forest & Wood Products Australia (FWPA), accessed July 20, 2025

View Source
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,
Direct Evidence

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

View Source
Preview of It is not just about birds: what do acoustic indices reveal about a Costa Rican tropical rainforest?, accessed July 18, 2025
It is not just about birds: what do acoustic indices reveal about a Costa Rican tropical rainforest?, accessed July 18, 2025
Contextual Support Journal

The relationship between the Acoustic Complexity Index and avian ..., accessed July 19, 2025

View Source
Preview of Listen up: new technologies for sound biodiversity monitoring - TERN Australia
Listen up: new technologies for sound biodiversity monitoring - TERN Australia
Contextual Support Government

Australian Acoustic Observatory | A2O – Australian Acoustic ..., accessed July 19, 2025

View Source
Preview of Open Ecoacoustics | ARDC - Australian Research Data Commons, accessed July 18, 2025,
Open Ecoacoustics | ARDC - Australian Research Data Commons, accessed July 18, 2025,
Contextual Support GreyLiterature

Open Ecoacoustics | ARDC - Australian Research Data Commons, accessed July 20, 2025

View Source
Preview of TERN. TERN – Australia's Ecosystem Observatory Network, highlights for 2018-2023.
TERN. TERN – Australia's Ecosystem Observatory Network, highlights for 2018-2023.
Contextual Support Government

Daintree Rainforest, Cape Tribulation BASE Contextual, Soil ..., accessed July 20, 2025

View Source
Preview of The Australian Acoustic Observatory | Request PDF - ResearchGate, accessed July 22, 2025,
The Australian Acoustic Observatory | Request PDF - ResearchGate, accessed July 22, 2025,
Methodology Source GreyLiterature

The Australian Acoustic Observatory, accessed July 24, 2025

View Source
Preview of The Australian Acoustic Observatory, accessed July 18, 2025,
The Australian Acoustic Observatory, accessed July 18, 2025,
Direct Evidence Journal

Robson Creek Rainforest Acoustic Data Collection - TERN, accessed July 20, 2025

View Source
Preview of The sound of restored soil: using ecoacoustics to measure soil biodiversity in a temperate forest restoration context - Research @ Flinders, accessed July 20, 2025
The sound of restored soil: using ecoacoustics to measure soil biodiversity in a temperate forest restoration context - Research @ Flinders, accessed July 20, 2025
Contextual Support GreyLiterature

The sound of restored soil: using ecoacoustics to measure soil biodiversity in a temperate forest restoration context - Research @ Flinders, accessed July 20, 2025

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Production Forestry
  • Assessment Conservation Target
  • Vegetation Forest
  • Evidence Type TargetCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 26 May 2026

Notes

No direct, published benchmark exists for this specific context. The benchmark assumes ACI is calculated from dawn/dusk chorus recordings in the primary biophony frequency band (e.g., 2-8 kHz) using standardized software. No upper detrimental threshold — higher values are always better up to natural saturation.