Scientific Foundation
Silent Pollution is grounded in four complementary layers of evidence: direct hydroacoustic research from Lake Sevan, foundational fish-bioacoustics research, and controlled studies on species related to Lake Sevan’s ishkhan and whitefish.
FOUNDATIONAL RESEARCH PAPERS
01 — LAKE SEVAN
Acoustic Properties of the Lake Sevan 2020
A.H. Mkrtchyan et al.
Direct field measurements of Lake Sevan acoustics. The study identified a characteristic response around 7.5 Hz, documented reverberation, and recorded acoustic signals associated with artificial sources including a boat and a passing cargo train. It establishes the local acoustic environment, not biological impact.
Armenian Journal of Physics, 13(2), 54–64 - »
02 — FISH BIOACOUSTICS
An Overview of Fish Bioacoustics and the Impacts of Anthropogenic Sounds on Fishes
Arthur N. Popper & Anthony D. Hawkins, 2019
A foundational review of fish hearing and anthropogenic underwater sound. Fishes detect particle motion, and human-generated sound can cause masking, behavioural and physiological responses and, at sufficiently intense exposures, injury. The authors emphasize that universal noise-effect thresholds for fishes are not scientifically justified.
Journal of Fish Biology, 94, 692–713 | DOI: 10.1111/jfb.13948 - »
03 — WHITEFISH ANALOGUE
Molecular and Cellular Responses to Long-Term Sound Exposure in Peled (Coregonus peled)
Sapozhnikova et al., 2020
A controlled study in the same genus as Lake Sevan whitefish. Prolonged high-level exposure to a 300 Hz tone produced changes in otoliths, auditory hair cells and cellular physiology. Changes became apparent after approximately ten or more days of exposure. This provides related-species evidence, not a Lake Sevan damage threshold.
Journal of the Acoustical Society of America, 148(2), 895–907 | DOI: 10.1121/10.0001674 - »
04 — ISHKHAN ANALOGUE
Does Soundpeaking Affect the Behavior of Chub and Brown Trout (Salmo trutta)? An Experimental Approach
Kowal et al., 2023
A controlled behavioural study using brown trout, a species in the same genus as ishkhan. Brown trout changed movement direction, aggregation and longitudinal position during playback of a changing underwater soundscape. The stimulus was a natural flood soundscape rather than motorboat noise, so the study supports acoustic sensitivity rather than a direct pollution threshold for ishkhan.
Fishes, 8(12), 581 | DOI: 10.3390/fishes8120581 - »
1. HOW FISH PERCEIVE SOUND
Fish do not perceive underwater sound through sound pressure alone. Particle motion is a fundamental acoustic stimulus detected by all fishes, and salmonids are particularly associated with low-frequency particle-motion sensitivity.
Silent Pollution uses hydrophone recordings to document the underwater acoustic environment, not to claim an exact representation of what a fish hears.
2. LAKE SEVAN AS AN ACOUSTIC ENVIRONMENT
A 2020 hydroacoustic study of Lake Sevan identified a characteristic response around 7.5 Hz, documented reverberation, and recorded signals associated with artificial sources including a boat and a passing cargo train.
The study demonstrates that Lake Sevan has a measurable acoustic environment. It did not investigate biological effects on fish.
Source: Mkrtchyan et al., 2020.
3. ISHKHAN & WHITEFISH
ISHKHAN — Salmo ischchan
Direct noise-effect studies on ishkhan have not been identified in the selected literature. In the related brown trout (Salmo trutta), experimental soundscape playback caused changes in movement, aggregation and spatial position.
WHITEFISH — Coregonus lavaretus
Direct noise-effect studies on Lake Sevan whitefish have not been identified in the selected literature. In the related Coregonus peled, prolonged high-level 300 Hz exposure produced changes in auditory hair cells, otoliths and cellular physiology.
In the related Coregonus peled, prolonged exposure to a high-level 300 Hz tone produced changes in auditory hair cells, otoliths and cellular physiology after at least ten days of exposure.
These studies provide related-species evidence, not direct proof of effects in Lake Sevan.
4. WHAT UNDERWATER NOISE CAN DO
Research on fishes shows that anthropogenic sound can lead to:
Masking — interference with biologically relevant acoustic information
Behavioural change — changes in movement, position or aggregation
Physiological stress
Auditory effects — under sufficiently intense or prolonged exposure
There is no universal noise threshold for all fishes. Effects depend on species, frequency, sound level, duration and environmental context.
5. WHAT WE KNOW — AND WHAT WE DON'T
This research gap is where Silent Pollution begins.
What is established:
Lake Sevan has measurable acoustic properties and receives artificial acoustic signals. Fishes detect underwater acoustic information, and related Salmo and Coregonus species have shown behavioural or physiological responses to acoustic exposure.
What remains unknown:
The specific effects of anthropogenic underwater noise on Salmo ischchan and Coregonus lavaretus in Lake Sevan.