A blue whale ’s song can travel Brobdingnagian distances . This means he or she can communicate with another heavyweight swim up to C of mi away .
scientist have noticed that the absolute frequency of whale calls are lower today than they were just twenty years ago , and they have no estimate why . They ’ve also recorded baleen hulk sound in the North Atlantic missing the " overtone " share of the call . Again , scientists are dumbfounded .
New Research published inScience Reports , however , suggest that the whales are choosing to do this – and that human activity is probably to blame .
Before now , it was believed a whale ’s call is generated by a resounding sound in the chambers of the animal ’s upper respiratory system . If this was the sheath , the relative frequency would count entirely on the size of the heavyweight – the bigger the hulk , the lower the frequence of its call . But research worker at Oregan State University ’s Hatfield Marine Center have prove this theory wrong .
First , they tape a spicy whale ’s call , then they build a model to try and mime the sound .
" We tried to envision a mechanics whereby giant could gradually lower the frequency of their calls through time , or farm birdcall with unusual harmonic structure , by only resonating sound in their upper respiratory bedchamber – and it was physically impossible , " said Robert Dziak , lead author and acoustic scientist with the National Oceanic and Atmospheric Administration ( NOAA ) , in astatement .
" Only when we pulsed atmosphere through the process of opening and closing the vocal corduroy did we get a way to bring on sounds that can modify frequencies in mid - call as well as remove overtones . "
So whales can mix up the oftenness of their calls by changing the pace they blow gentle wind through their outspoken corduroys .
" That also hint that the change in the frequency might be cognitive . They are choosing to make it higher or lower in response to some sort of environmental stimulus , " added Dziak .
But why the absolute frequency exchange ? One proffer is that it ’s a reply to an increase in human - generated auditory sensation . whale are exchange the frequency of their call to a radio channel with less static , if you will .
Or it could be because there are more blue whales than there were a distich of decades ago . Do n’t get too excited though , they ’re still listed on theIUCN Red Listof endangered animals and new research also shows thirty years after the hunting ban , they’renot recovering as fast as thought .
" depleted - frequency sounds can be produced at low intensity by the animal than high - frequency sound and yet low - frequency audio still travels further , " said Dziak .
" Those factor may also make for a function in the vocalization changes over the past two X . "
