| Resumen |
This paper summarizes several results about urban acoustic impact as well as some papers published by the research group on aircraft noise are cited. The experimental place is the Mexico City. A distributed wireless monitoring system was developed and installed in the Historical Centre. Each node includes a half-inch pre-polarized IEC 61672 Class 1 microphone mounted 4m above the road surface in a weatherproof case, a dynamic range data acquisition card, an industrial computer and wireless connection to Internet by means of a 3G Mobile Broadband. The noise level measurements at each point is made every 30 seconds, at 25 Ks/s and 24-bit resolution analog-to-digital conversion (ADC), and the data are sent to the main monitoring station every five minutes. Additionally, a non-permanent point in the airport periphery allows evaluating the aircraft takeoff noise. The standards recommend that noise emissions should be no more than 68 dB(A) during the day and 65 dB(A) at night. Nevertheless, the environment noise in many points had levels between 77 and 83 dB(A), which are very annoying and could produce hearing loss with too much exposure. Urban noise patterns were obtained during one year. This assessment helped to take action to improve the comfort and reducing the harmful impact in critical areas. Aircraft classification based on spectral characteristics of the take-off noise using real time measurements enhances the system performance to alleviate noise pollution. |
