Design and performance of a microprobe attachment for a 12-in. microphone
Bibliographic record
Abstract
It is often necessary to measure sound fields in confined spaces where minimum disturbance of the sound field is important. In applications where the confinement of the space is extreme such as very small cavities, existing probe microphones are too large. In this paper the probe section of a Brüel and Kjær probe microphone type 4170 is redesigned using smaller diameter probe tubes. New designs (microprobes) are first considered through simulations in the case of probe tubes having inside diameters ranging from 1.25 down to 0.1mm. Several microprobes were constructed and their performance measured and compared to the simulated results. Good agreement was found between the measured and simulated frequency response and sensitivity. Measurements show that a sensitivity of about 0.02mV∕Pa could be obtained from a probe tube with 0.2mm o.d. and 0.1mm i.d. if the length is less than 1cm. The input impedance of the probe orifice is estimated to be greater than 3×1010kgs−1m−4. Viscous resistance and thermal conduction due to the small diameter provides a well-behaved frequency response that is flat within 5dB between 200 and 6000Hz and to within 12dB up to 10000Hz.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.005 |
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".