Security Monitoring Using Microphone Arrays and Audio Classification
Bibliographic record
Abstract
In the paper, the authors propose a security monitoring system that can detect and classify the location and nature of different sounds within a room. This system is reliable and robust even in the presence of reverberation and in low signal-to-noise (SNR) environments. We describe a novel algorithm for audio classification, which, first, classifies an audio segment as speech or nonspeech and, second, classifies nonspeech audio segments into a particular audio type. To classify an audio segment as speech or nonspeech, this algorithm divides the audio segment into frames, estimates the presence of pitch in each frame, and calculates a pitch ratio (PR) parameter; it is this PR parameter that is used to discriminate speech audio segments from nonspeech audio segments. The discerning threshold for the PR parameter is adaptive to accommodate different environments. A time-delayed neural network is employed to further classify nonspeech audio segments into an audio type. The performance of this novel audio classification algorithm is evaluated using a library of audio segments. This library includes both speech segments and nonspeech segments, such as windows breaking and footsteps. Evaluation is performed under different SNR environments, both with and without reverberation. Using 0.4-s audio segments, the proposed algorithm can achieve an average classification accuracy of 94.5% for the reverberant library and 95.1% for the nonreverberant library
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".