Acoustic measurements on mid-shelf sediments with cobble: Implications for reverberation
Bibliographic record
Abstract
The vast majority of sediment acoustics research has focused on rather homogeneous sandy sediments. Measurements for sediments containing cobbles (grain size greater than 6 cm) are rare. Here, measurements are presented for mid-shelf sediments containing pebbles/cobbles mixed with other grain sizes spanning 7 orders of magnitude, including silty clay, sand, and shell hash. The 2 kHz sediment sound speed in two distinct layers with cobble is 1531±5 m/s and 1800±20 m/s at the 95% credibility interval. The dispersion over the 400–2000 Hz band was relatively weak, 2 and 7 m/s respectively. The objective is to (1) present results for a sediment type for which little is known, (2) motivate development of theoretical wave propagation models for wide grain size distributions, and (3) speculate on the possibility of cobble as a scattering mechanism for mid shelf reverberation. The presence of cobbles from 1 to 3 m (possibly extending to 6 m) sub-bottom suggest they are the dominant scattering mechanism at this site. Though sediments with cobbles might be considered unusual, especially on the mid-shelf, they may be more common than the paucity of measurements would suggest since typical direct sampling techniques (e.g., cores and grab samples) have fundamental sampling limitations. [Research supported by ONR Ocean Acoustics.]
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".