Measurements of directional properties of reverberant sound fields in rooms using a spherical microphone array
Bibliographic record
Abstract
The directional variation of sound at a point has been studied in three rooms, using a measurement system described previously [J. Acoust. Soc. Am. 112, 1980–1991 (2002)]. The system uses a pair of 32-element spherical microphone arrays to obtain directional impulse responses in each of 60 steering directions, with an angular resolution of 28°, covering all directions in the whole solid angle. Together, the array measurements span the frequency range from 300 to 3300 Hz. The angular distribution of incident sound energy is visualized on a three-dimensional plot, and quantified by computing the directional diffusion and the directional peak-to-average level difference (“anisotropy index”) of the sound field. The small-to-medium-sized rooms had reverberation times of 360, 400, and 600 ms. Measurements were made for several source and receiver locations in each, and were analyzed over several time ranges (full decay time of room, late time decay, 2-ms windows throughout the decay). All measured sound fields were found to be highly directional, the distribution of arriving energy at a point greatly influenced by the early specular reflections. The directions and arrival times of these reflections were identified from the measurements, giving excellent agreement with those expected from knowledge of the room geometry. It was observed that as time progressed, the sound fields initially exhibited increasing isotropy, followed by increasing anisotropy, due to nonuniform absorption in the rooms. The measurement system is capable of yielding detailed information about the reverberant sound field in a room, and is easily modified to be able to analyze ambient or time-varying fields.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".