Chile’s fixed-source noise standard is built around human receptors: its limits are defined at dwellings and it separates day from night according to when people rest. Wildlife does not appear in it, and a good share of the projects entering the SEIA are sited where the nearest receptor is not a house but a habitat. That gap is addressed by the SEA’s Criterio de evaluación en el SEIA: Evaluación de impactos por ruido sobre fauna nativa (SEIA assessment criterion on noise impacts on native fauna).
When it applies
It does not depend on the type of project or on the route of entry: it applies to Environmental Impact Declarations and to Environmental Impact Studies alike. What triggers it is broader than usually assumed: that the project produces a difference in noise levels between the with-project and without-project situations in an area holding native terrestrial fauna habitat relevant for nesting, breeding or feeding. That is why many developers find out late, once the observation has already arrived. A common mistake, in fact, is for the fauna survey to concentrate on records taken inside the project site rather than in its surroundings.
Why a fixed-source measurement is not enough
A measurement taken for the standard yields an overall A-weighted level, because A-weighting mimics the human ear. Animals do not hear as we do: some species perceive low frequencies better, and others communicate where A-weighting discounts energy that matters to them. That is why the criterion uses the equivalent continuous sound pressure level but without frequency weighting (levels in dB), and requires spectral content in octave or third-octave bands.
The practical consequence: a measurement made for fixed sources cannot be reused here. It gives a single figure where spectra are needed. If the baseline was gathered without knowing the project would have a fauna component, it means going back to the field.
What it demands of the baseline, and which effects must be analysed
The baseline is the most demanding part, because it imposes conditions that compete with each other: measurements must be taken during the seasons of greatest sensitivity for the species, coincide with the project’s activity periods and represent the moments of lowest background noise, under constrained meteorological conditions, with instrumentation holding current ISP certification and with spectral recording. That ties the campaign to a window in the year, not to the project’s schedule.
On that basis, the analysis must address the masking of the signals species use to communicate, behavioural alterations —vocalisation, feeding, movement, breeding success— and direct physical damage. Thresholds are organised by species group, type of effect and type of source: it is a table to apply, not to read.
Key points for assessing noise effects on fauna
- The baseline points. Define noise baseline points that represent the habitats of the fauna of interest near the project.
- The impact thresholds. Define the impact thresholds for the species under study. The SEA criterion provides reference thresholds, but they are not always the most appropriate ones.
- The assessment scenarios. Define scenarios that account for the least favourable condition for the fauna, not only for human settlements.
- The significance analysis. Analyse whether the impact is significant where a behavioural threshold is exceeded.
How we work with you
In our environmental impact and vibration studies for the SEIA, the fauna assessment sits inside the same study rather than as an annex: the team that designs the campaign is the one that models, assesses and answers the SEA’s observations. It matters because what decides the outcome —when measurements are taken, at what spectral resolution, which species are justified— is decided at the start.
If your project is being assessed in an area with native fauna, or you have already received an observation, book a 20-minute call. And if you have fixed sources in operation, look at this alongside D.S. N°14/2024: they are two different assessments of the same sources.
He leads Acústica Austral’s environmental noise and vibration studies for the SEIA across energy, port and infrastructure projects, and has contributed to reference work for Chile’s Ministry of the Environment.
Meet the team →Free resources for your project
Guide to the D.S. N°14/2024 and the acoustic checklist for entering the SEIA, in PDF. We email them to you.