Acoustical model for Shoddy-based fiber sound absorbers
Bibliographic record
Abstract
A simple equivalent fluid model is proposed to describe the acoustic behavior of post-consumer and post-industrial recycled fibers otherwise known as Shoddies. The model requires knowledge of the bulk density only, a parameter that is easily measured. Characterization testing was completed on nine Shoddy fiber constructions processed by one of three different methods: thermal bonding, resin bonding, and mechanical bonding. The parameters measured directly were bulk density, open porosity, tortuosity, static airflow resistivity, and normal incidence sound absorption. The materials’ viscous and thermal characteristic lengths and static thermal permeability are determined using indirect acoustical techniques. Empirical relationships linking the material parameters to the bulk density are then substituted into several popular equivalent fluid models. The most accurate ‘simplified’ model is selected by comparing each model’s ability to accurately predict the materials’ acoustic behavior using normal incidence sound absorption to assess performance. The present work is of interest to sound engineers in predicting the acoustic performance of Shoddy-based absorbers.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".