No abstract

Noise pollution is an underappreciated component of global environmental change and can impact species that have a strong reliance on acoustic communication. In urban areas, traffic noise can interfere with the ability of animals to communicate and complete essential aspects of their daily lives. We investigated the impact of traffic noise on the calling behaviour of the brown tree frog (Litoria ewingii) in south‐eastern Melbourne, the fastest‐growing human population centre in Australia. We placed six acoustic recorders at increasing distances from a busy suburban road and recorded the calling behaviour (call pitch and call rate) of brown tree frogs immediately before and after loud traffic noises, and in response to different chorus sizes. Traffic noise resulted in a significant, but short‐term, increase in call pitch in the brown tree frog. Both call pitch and call rate decreased with increasing distance from the road, yet traffic noise still resulted in increased call pitch even 200–300 m from the road. Conversely, although traffic noise increased call pitch across all chorus sizes of the brown tree frog, larger chorus sizes were associated with decreased call pitch. Our study highlights the pervasive, and sustained, impact that anthropogenic noise can have on urban frog populations.

No abstract

The monolithic-crystal filter has two or more pairs of electrodes on the same piezoelectric plate; mechanicalwave propagation in the regions between electrodes takes place in an evanescent mode. A method of analysis, based on solutions to the wave equation, is first developed in general terms and then applied specifically to AT-cut quartz. Boundary conditions are used to determine resonant frequencies and vibration patterns under short-circuit conditions; from these, the electrical equivalent circuit is developed. Experimental results confirm the validity of the method. The theoretical results presented describe the bandwidth and motional capacitances of 2-and 3-resonator filters as functions of their geometry (electrode width, thickness and spacing). A method of predicting unwanted resonances is developed. A 3-resonator filter, with a centre resonator of different geometry, is considered. Some results relevant to multiple-resonator filters (up to ten) are described. Extension of the theory to overtone-mode devices is also discussed. List of principal symbols2a = length of electrode 2b = thickness of plate c = elastic constant Id = spacing between electrodes h = piezoelectric constant k = piezoelectric coupling coefficient m = distinguishing wth resonance of the filter with short-circuited electrodes // = integer describing standing-wave pattern across thickness, n = 1 for the fundamental thickness mode q = charge u = particle displacement x = co-ordinate ABFG = amplitude constants C = capacitance (eqns. 26, 27) D = electric flux density E = electric field strength L = total number of trapped modes of resonance N = number of resonators in filter (electrode pairs) S = strain T = stress V = potential difference Y = admittance l/j8 = permittivity p -density /A = discontinuity between region with and without electrodes (eqn. 22) y = elastic constant (eqn. 9) co co = angular frequency at which propagation in region without electrodes becomes evanescent (eqn. 21) <£ = U)/OJ CO (eqn. 20) £, 7], a = spatial variations of vibration patterns (eqns. 13-17) £, rj, a = normalised versions of £, 17, a (eqns. [23][24][25]

No abstract