Whale calls becoming deeper to compensate for marine traffic

29th Aug 2017

New research suggests that the pitch of whale song in the ocean has becoming lower in recent years, possibly to compensate for the increase in noise pollution from marine traffic.

Researchers at the National Oceanic and Atmospheric Administration (NOAA) observed the changes during a study into blue whale vocalisations, published last month in Scientific Reports.

The findings also shed light on the mechanism by which blue whales modulate the sound they produce, with the previous hypothesis that whale calls are generated by chambers in the upper respiratory system now appearing to be incorrect, with the scientists explaining a more likely mechansim.

"Only when we pulsed air through the process of opening and closing the vocal cords did we get a way to produce sounds that can change frequencies in mid-call as well as remove overtones." said lead author and NOAA acoustic scientist, Robert Dziak in a statement.

To find out more, read the article in full here.