A Brief Review on Acoustic Analysis in Quality Evaluation and a New Method for Determining Bulk Density of Aggregate

The purpose of this study is to provide a brief review on acoustic analysis in quality evaluation and a new method for determining bulk density of aggregate. An acoustical system was developed to measure aggregate density. The system includes three microphones, a steel plate, a sinker, an isolated body and digital signal processing hardware. The steel plate was placed on aggregate, followed by releasing the sinker on the steel plate. Then, the acoustic impact was analyzed using speech recognition technology. Aggregate samples at different densities were prepared using ASTM Standard C29. Next, using the acoustical system, audio signals were collected. A neural network was developed for sound data classification into three aggregate densities (good density, medium density, and low density). The classification accuracy was 77.1% on the test set and 96.5% on all data sets. The other neural network was developed for sound data classification into two aggregate densities (good density and low density). The classification accuracy was 90.6% on the test set and 89.6% on all datasets.