Laboratory performance of the single-sided E-A-R® combat arms hearing protective earplug
Bibliographic record
Abstract
The objective of this study was to compare the effect of wearing conventional and passive level-dependent hearing protection earplugs on hearing and horizontal plane sound source identification, in quiet. A single device was tested that incorporated these as separate modes of operation. Ten males and ten females with normal hearing participated. Each was tested with the ears unoccluded and fitted binaurally with the device in each mode. Measurements were made of free-field hearing thresholds for one-third octave noise bands with centre frequencies ranging from 250 Hz to 8000 Hz and the ability to discriminate among eight speakers surrounding the subject at a distance of 1 metre. The stimulus was a 300-ms, 75-dB SPL white noise burst. The sound attenuation was derived from the hearing thresholds. With the device in the conventional mode, mean thresholds were in the range of 36.2 dB to 53.3 dB SPL, signifying an induced mild hearing loss. In the level-dependent mode, thresholds were at most 37.9 dB SPL. Mean attenuation values were generally similar to the manufacturer's specifications. There was no effect of gender. Percent correct for sound source identification decreased by 40% with the conventional mode and by 20% with the level-dependent mode. Degree of attention, then appears to be a key factor for outcome. However, an analysis of error types showed that the level-dependent mode of operation resulted in a frontward bias that was similar to that observed previously with a device incorporating external microphones for enhanced communication.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".