I. Pavón

Great tits, Parus major, increase vigilance time and reduce feeding effort during peaks of aircraft noise

Antipredator vigilance may take a significant amount of time, leading to a trade-off between foraging and vigilance. Studies show that this trade-off is modulated by the perception of predation risk faced by individuals. Anthropogenic noise can disturb acoustic communication by masking both direct predator detection and the perception of conspecific alarm calls. We would expect a decrease in acoustic awareness to be compensated for by an increase in visual awareness. Thus, we tested whether increases in noise produced by commercial aircraft reduced foraging effort and increased vigilance time in great tits. We videotaped birds feeding on peanut feeders in the vicinity of Barajas airport (Madrid, Spain), and measured behavioural sequences before, during and after aircraft sound events. Our results show that, when aircraft noise peaked, the proportion of time devoted to vigilance was maximal, while that devoted to feeding was minimal. As a result, the ratio between vigilance and foraging was at its maximum when aircraft noise was loudest, being almost double that during baseline levels. The duration of vigilance episodes was strongly correlated with noise levels. Also, the duration of feeding bouts was at its lowest during the peak of noise, and increased after this period. We suggest that these behavioural modifications help foragers visually detect possible predators in those situations in which high levels of noise hamper sound perception. Our study suggests that behavioural plasticity could contribute to the resilience of avian populations exposed to anthropogenic disturbance.

Airport noise insulation programs: The Spanish case

Noise pollution around airports is one of the most important problems in environmental acoustics. The incessant development of modern societies is continuously increasing the demand for air transport, and airports have to grow to adapt their operational capacity to the new requirements. On the other hand, the economic activity related to airports is closely linked to the expansion of built-up areas around them. Consequently, two completely incompatible land uses are forced to coexist, causing airport capacity to remain limited while the inhabitants do not cease to be annoyed by aircraft noise. Although there are several international initiatives setting the focus on the reduction of noise at the source, people living in residential areas around airports need urgent solutions. Among others, the implementation of sound insulation programs is one of the most widely-adopted solutions worldwide, as it allows a reduction of sound levels in the interior of dwellings, while the operational capacity of the airport remains unaffected. The definition and application of a sound insulation program is a very complex process that needs to manage several opposing factors: health, annoyance, airport capacity, economic costs of insulation measures… In this paper we describe the case of Spanish airport insulation programs. We set the focus on a concise description of the full process, from the creation of noise maps, to the checking of installed soundproofing measures, as carried out by the Spanish administration. As a result of this process, thousands of dwellings and houses have been acoustically insulated to meet indoor noise comfort criteria in Madrid, Mallorca and Malaga airports, among others.

European Blackbirds Exposed to Aircraft Noise Advance Their Chorus, Modify Their Song and Spend More Time Singing

Noise pollution has a strong impact on wildlife by disrupting vocal communication or inducing physiological stress. Songbirds are particularly reliant on vocal communication as they use song during territorial and sexual interactions. Birds living in noisy environments have been shown to change the acoustic and temporal parameters of their song presumably to maximize signal transmissibility. Also, research shows that birds advance their dawn chorus in urban environments to avoid the noisiest hours, but little is known on the consequences of these changes in the time they spent singing at dawn. Here we present a comprehensive view of the European blackbird singing behaviour living next to a large airport in Madrid, using as a control a population living in a similar but silent forest. Blackbird song is composed of two parts: a series of loud low-frequency whistles (motif) and a final flourish (twitter). We found that airport blackbirds were more likely to sing songs without the twitter part. Also, when songs included a twitter part, airport blackbirds used a smaller proportion of song for the twitter than control blackbirds. Interestingly, our results show no differences in song frequency between airport and control populations. The most relevant finding of this study shows that airport blackbirds not only sang earlier but also increased the time they spent singing when chorus and aircraft traffic coincide on time. This effect disappeared as the season progressed and the chorus and the aircraft traffic day-time schedule were separated on time. We propose that the typical urban upshift in frequency might not be useful under the conditions of noise and landscape structure found near airports. We suggest that the modifications in singing behaviour induced by aircraft noise may be adaptive and that they are specific to airport acoustic habitat. Moreover, we found that adjustment of singing activity in relation to noise is plastic and possibly optimized to cope with aircraft traffic activity. In a soundscape characterised by intermittent and strong noise bursts, singing for longer could be more advantageous than modifying frequency parameters, although it is likely more costly.

Assessment of Noise Exposure During Commuting in the Madrid Subway

Because noise-induced hearing impairment is the result not only of occupational noise exposure but also of total daily noise exposure, it is important to take the non-occupational exposure of individuals (during commuting to and from their jobs, at home, and during recreational activities) into account. Mass transit is one of the main contributors to non-occupational noise exposure. We developed a new methodology to estimate a representative commuting noise exposure. The methodology was put into practice for the Madrid subway because of all Spanish subway systems it covers the highest percentage of worker journeys (22.6%). The results of the application highlight that, for Madrid subway passengers, noise exposure level normalized to a nominal 8 hr (LEx,8h-cj ) depends strongly on the type of train, the presence of squealing noise, and the public address audio system, ranging from 68.6 dBA to 72.8 dBA. These values play an important role in a more complete evaluation of a relationship between noise dose and worker health response.

Platform for on-board real-time detection of wet, icy and snowy roads, using tyre/road noise analysis

In this paper, a new approach capable of detecting water, ice and snow on the road surface is shown, focusing on the hardware needed for the practical implementation. Proposed platform uses a simple microphone and a general purpose microcontroller. The system is tightly integrated with vehicle ECUs (Electronic Control Units). A CAN bus allows it to read some of the variable dynamics provided by the sensors already installed in virtually every motor vehicle. Detector results are also published through the CAN bus to be displayed on the vehicle console and to be used by other ECLs. Proposed system is simple, cheap and easy to install. Initial tests for the wet/dry detector classes have shown a very high success rate.