Evaluation of Aircrew Noise Exposure Levels on a Canadian CH-147F Chinook Helicopter
Bibliographic record
Abstract
The cabin and cockpit noise levels of a Royal Canadian Air Force CH-147F Chinook medium to heavy lift utility helicopter were evaluated in this study. The sound pressure levels were measured at nine aircrew locations through 43 unique and representative flight and ground conditions in accordance with the ISO 5129:2001 standard. Additionally, the performance of a combination of currently in service helmets and headsets were evaluated in accordance with the ANSI Standard S12.42. The hearing protection performance results were used in combination with the measured sound pressure levels to evaluate the performance of the hearing protection in the context of the CH-147F noise environment. Results showed that the David Clark headsets equipped with active noise reduction provided the most superior hearing protection. The maximum exposure limit duration was calculated for each microphone location, hearing protector performance and flight condition combination. It was found that the David Clark headsets provided sufficient protection for an unlimited duration of exposure for an individual with a properly fitted headset. It was also found that improperly fitted hearing protection could result in an increased risk of hearing damage after merely 18 seconds.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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".