Environmental Noise & Cardiovascular Stress Response

Noise Source

Sound level L_Aeq 62 dB

Time period (day/evening/night penalty)

Years of chronic exposure 10 yr

Insulation
double-glazing / facade retrofit (−12 dB)

Physiological Readouts

Stress hormone index

Resting heart rate

70 bpm

Systolic BP

115 mmHg

Highly annoyed

Chronic ischemic heart disease relative risk (WHO exposure–response, L_den)

RR = 1.00

How it works

Chronic environmental noise activates the hypothalamic-pituitary-adrenal axis and sympathetic nervous system even below the level of conscious annoyance — the WHO's "noise-stress" model (Babisch, 2002). This simulator drives a minimal allostatic-load ODE from the effective day-evening-night exposure level:

L_eff = L_Aeq + period_penalty − mitigation_dB
drive  = max(0, L_eff − 40)              [dB above the ~40 dB quiet baseline]
S_target = clamp(1.8 · drive, 0, 100)     [steady-state stress-hormone index]
dS/dt  = (S_target − S) / τ               [first-order relaxation, τ ≈ 20 s]

HR  = 70 + 0.5·S            (bpm)
SBP = 115 + 0.35·S          (mmHg)

Long-term risk uses the WHO 2018 Environmental Noise Guidelines pooled estimate for road-traffic noise and ischemic heart disease — roughly an 8% relative-risk increase per 10 dB of L_den above a 53 dB threshold:

RR(IHD) = 1.08 ^ ((L_den − 53) / 10),   for L_den > 53 dB

"Highly annoyed" uses the Miedema & Oudshoorn (2001) exposure-response curve fitted to European road-traffic-noise surveys. The years of chronic exposure slider sets how close the stress index starts to its steady state (allostatic load builds but only partially habituates); the insulation toggle models a realistic 12 dB façade/glazing reduction. Sound rings in the 3D view visualise propagation loss from the source toward the dwelling; the pulsing heart's beat rate and colour track the live simulated heart rate and blood pressure.

Sound propagation rings Circulating "blood cell" markers

L_eff ≈ 62 dB
HR 70 bpm

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