“You might like waking up when it’s quiet, but in the evening you might want the vibrancy,” said Stephen Dance, professor of acoustics at London South Bank University and another of the project’s leaders. Some of the noise created by human activities lies beyond the threshold of hearing, especially at very low frequencies of around a few oscillations per second (a few hertz or Hz). Vibrations like these are detectable using technologies attuned to seismic waves – trains and construction, for example, shake the ground at such frequencies. Data like this could even be helpful for controlling the pandemic, for example by showing how well people are adhering to social distancing and travel restrictions. Basically, we are probably missing a lot of the small earthquakes that we might otherwise detect becausethey are getting drowned out.” But these might become visible in the lockdown data. “High levels of sound can physically harm and kill marine animals, or cause permanent or temporary hearing loss, and can trigger behaviouralresponses like flight, stress and disruption of feeding.” He and his co-worker Dugald Thomson have studied how such noise changed during lockdown, both in the open ocean (in the north-east Pacific) and in an inland waterway in the Strait of Georgia outside the port of Vancouver. They saw a small drop in the weekly average noise at frequencies of about 100Hz in the open ocean, and a larger decrease in the strait. “These lessons can then be applied to bigger questions of the overall influences of aerosols on climate and society.” “We’re all hoping that we can make the best of a bad situation and learn something useful,” said Samset.
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