Trends in low-frequency deep ocean ambient noise levels: New results from old data.
Bibliographic record
Abstract
Concern about effects of anthropogenic sound generated by ships, seismic exploration, naval operations, and ocean acoustic research on marine life has stimulated new studies of marine animal bioacoustics. An underlying issue in assessing the noise impact establishes the present-day background noise level and compares it to noise levels from previous times. The most generally accepted prediction of noise level trend at low frequencies (below 500 Hz) is due to Ross, who used noise levels from the 1950s and the mid-1960s to predict an increase of about 3 dB/decade. This paper addresses the issue of the trend in low-frequency ambient noise levels in the ocean and presents measurements taken in the intermediate years between the mid-1960s and the present time. The measurements were made using a calibrated multi-element volume array (MEVA) at deep ocean sites in the Northeast Pacific from 1978 to 1986. The array provided spectral noise levels and horizontal and vertical directionalities. Compared to the 1965 values, the MEVA values are 6–8 dB greater between 10–50 Hz and 1–3 dB greater from 50–400 Hz, respectively. The data presented here provide evidence that the trend predicted by Ross extended at least into the mid-1980s.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".