Cicadas. Their pulsating rhythms are hypnotic, their tone crisply cuts through the hot summer air, and their deafening volume can be exhilarating. This post follows a track down to the valley-floor of Nightcap National Park. As the track progresses into the cooler depths of the valley the rhythms and pitch of the cicadas change.

At the commencement of the walk the cicadas maintain a regular beat, though their volume suddenly drops at 2’19”. At the top of the escarpment the cicadas luxuriate in the warmth of the forest canopy:
https://soundslikenoise.files.wordpress.com/2011/12/minyon-cicada.mp3

A few hundred metres down the track the familiar pulse of the cicada emerges. Is this change due to a minute drop in temperature or light? Here the sounds of eucalyptus seeds can also be heard as they fall by the microphone:
https://soundslikenoise.files.wordpress.com/2011/12/minyon-cicada2.mp3

Walking further downwards the pitch of the cicadas begins to deepen, their rhythmic pulse becomes more pronounced:
https://soundslikenoise.files.wordpress.com/2011/12/minyon-cicada5.mp3

The final colony of cicadas is heard about half-way down the track. Perhaps the cooler temperature prevents them from inhabiting the bottom area of the valley. Again their pitch is slightly lower than before, their pulse resembling a steady heart-beat:
https://soundslikenoise.files.wordpress.com/2011/12/minyon-cicada6.mp3

Walking along this track can be a breath-taking experience; the forest is stunning, the wildlife is plentiful, and the waterways are tranquil. However it is the sonic world of the cicadas which enhance the valley, their voices providing a dramatic dimension to the trek throughout the summer months.