Reframing Environmental Acoustics: Soundscapes as a Design Parameter, Not a By‑Product
By Prof Eoin King, University of Galway, Ireland
Conventional environmental noise assessment is built on a simple but limited premise: quantify unwanted sound, compare it against thresholds, and mitigate where necessary. This model, effective in identifying harmful exposure, has nonetheless created a structural blind spot in the discipline. By focusing almost exclusively on sound levels, contemporary practice often overlooks the broader acoustic experience within which those levels are embedded.
While this exposure-based paradigm has delivered significant public health protections, its regulatory success has also entrenched an assumption that acoustic quality is reducible to energy metrics. The EU Environmental Noise Directive requires Member States to assess the need for actions on the protection of quiet areas in an agglomeration and in open country. Quiet areas in open country are not determined by sound levels alone, but rather an area, delimited by the competent authority, ‘that is undisturbed by noise from traffic, industry or recreational activities’, thus introducing a qualitative acoustical definition.
There is growing recognition that future acoustic assessment must evolve from compliance with a numerical limit value to include consideration of the impact of increasing sound levels or changing the character of the sound in existing acoustic environments. The emerging shift does not replace energetic indicators but repositions them within a wider, perceptually informed framework. This is where soundscape principles introduce some operational novelty: they provide a way to describe, evaluate, and design acoustic environments according to function, use, and experience, not only exposure.
This repositioning aligns with the conceptual framework established in the ISO 12913 series, which defines soundscape as the acoustic environment as perceived or experienced and/or understood by people, in context.
The Central Problem: Level-Based Metrics Cannot Define Acoustic Quality
Noise indicators such as LAeq and Lden quantify energy but cannot, by themselves, define the quality or appropriateness of an environment. Two environments may exhibit comparable equivalent continuous sound levels while differing substantially in perceptual character and functional suitability. The sound pressure level of road traffic noise can be approximately the same as waves crashing on a beach; even their spectral profiles may partially overlap, yet the perceptual and contextual meanings of these sounds differ fundamentally. Thus, two sites with identical exposure can differ fundamentally in perceived quality due to spectral content, temporal patterning, masking characteristics, and the intended activity in the space.
This disconnect is more than a theoretical issue, it constrains design. Level-based thresholds can reduce harmful exposure yet fail to improve, or even recognise, the acoustic performance of a space. As long as noise assessment focuses on the reduction of unwanted sound, it remains reactive, addressing deficiencies rather than shaping outcomes. In this sense, conventional practice evaluates compliance rather than performance. What is needed is not a more refined measure of unwanted sound, but a systematic way to articulate desired acoustic attributes.
Soundscapes as Functional Design Criteria
The most significant contribution of soundscape methodology is its repositioning of sound as a design parameter within the built and natural environment. Rather than treating sound as an externality to be controlled, soundscape assessment defines how an environment should perform acoustically, based on its purpose.
For example, a public plaza may require a degree of acoustic liveliness to support social interaction, a green corridor might prioritise natural sound to support restoration and biodiversity, and a transport concourse may need temporal clarity for wayfinding and information. These are not noise control problems; they are acoustic design specifications.
Framing these requirements as performance objectives situates acoustics alongside other environmental design parameters such as thermal comfort, lighting quality, and spatial legibility.
By describing acoustic environments in perceptual terms such as calmness, vibrancy, or continuity, soundscape methods provide vocabulary and metrics that better align with urban design, landscape architecture, health, and user experience. This cross-domain compatibility is a fundamental innovation. Importantly, such perceptual descriptors are not purely subjective abstractions; structured survey instruments and circumplex-based analytical models provide reproducible methods for linking experiential attributes to measurable environmental conditions.
Figure: Similar levels, different meanings – coastal surf and road traffic can measure alike in decibels, yet diverge profoundly in perception.
Towards a Resource-Based Acoustic Paradigm
Perhaps the most novel shift introduced by soundscape thinking is the concept of the acoustic environment as a resource. The aim is not silence, but the appropriate acoustic conditions for the intended use of a space. This contrasts sharply with the pollutant model that views all sound as potentially problematic until proven otherwise. A resource-oriented model is proactive, enabling cities to plan for acoustic value rather than merely avoid acoustic harm.
This does not reject the pollutant model but reframes it within a dual perspective: environmental sound constitutes both exposure to be managed, and experiential value to be cultivated.
Integrating Soundscape Methodologies into Technical Practice
To embed soundscape principles within existing assessment frameworks, several methodological steps are proposed:
- Coupling Energetic and Perceptual Metrics
Physical measurements remain essential, but they are interpreted alongside perceptual constructs derived from established psychoacoustic metrics and soundscape instruments (e.g. the ISO 12913 series on soundscapes). This coupling enables acoustic indicators such as LAeq, spectral distribution, or psychoacoustic parameters to be analysed in relation to reported perceptual dimensions such as pleasantness or eventfulness.
- Aligning Acoustic Criteria with Spatial Function
Assessment parameters are defined according to what the environment is intended to support: conversation, recreation, focus, biodiversity, or transit. Functional alignment requires early-stage dialogue between acousticians, planners, and designers to define context-specific acoustic objectives rather than applying uniform level thresholds.
- Introducing Acoustic Performance Targets
Rather than only limiting maximum levels, performance-driven criteria specify desirable acoustic attributes such as masking effectiveness, temporal stability, or spectral balance.
- Embedding Assessment Early in Planning
Soundscape objectives are incorporated in the conceptual design phase, enabling integration with materials, geometry, planting strategies, and circulation patterns. Early integration reduces the likelihood that acoustics becomes a late-stage mitigation exercise and instead positions it as a formative design influence.
- Using Participatory and Observational Data Strategically
Community input and behavioural observations enrich technical assessments without compromising their rigour, and potentially increasing social acceptance.
A Hybrid Assessment Model for the Future
The future of environmental acoustics lies in a hybrid model in which sound level indicators provide the safety baseline and soundscape metrics define the qualitative ambition. In practice, this means that dB metrics will determine compliance and health protection, but soundscape indicators would determine whether a space sounds appropriate.
Such a two-layer framework reconciles regulatory robustness with experiential nuance, offering a structured pathway from exposure control to acoustic performance design. This two-layer system might offer both robustness and nuance, making acoustic assessment not simply a regulatory exercise but a design discipline capable of shaping high‑quality environments.
Prof Eoin King, University of Galway, Ireland
