Whale sounds appeared to break the speed of sound: Wave interference explains the mystery
It has been stated that the unusual speed data observed in whale sounds recorded off the coast of Massachusetts is not caused by the sound accelerating, but rather by wave interference.
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Hydrophone data used by oceanographers to track whale movements initially revealed a result that seemed to defy the laws of physics. In analyses conducted off the coast of Massachusetts, some whale sounds were recorded as if they were traveling faster than the natural speed of sound in water.
John Spiesberger, an oceanographer at the University of Pennsylvania, initially considered this result from the software he developed to be a technical glitch or a coding error. However, when the code was examined in detail, no obvious errors were found. Thus, the researchers turned to physical processes to find the source of the anomaly in the measurements.
Hydrophone networks placed on the seabed are used to determine the location of whales. In these systems, the location of the creature can be determined by calculating the time difference of sounds reaching different receivers. However, signals coming from whales moving near the surface can produce unusual results in these calculations.
SOUND DID NOT ACCELERATE, THE SIGNAL PEAK SHIFTED FORWARD
According to the assessment by Spiesberger and Eugene Terray from the Woods Hole Oceanographic Institution, the reason for the unusual recording is that the direct sound wave and the echo reflected from the water surface reach the hydrophones at the same time. When these two waves combine, the power and shape of the signal change; the peak point recorded by the receiver occurs earlier than normal.
Therefore, the sound itself does not exceed the speed limit in water. The "faster" effect seen in the measurement is explained as an acoustic illusion caused by the overlapping of waves. The researchers state that this situation is consistent with the unexpected wave interference effect defined within the scope of Albert Einstein's special theory of relativity.
In the next phase of the study, it is aimed to experimentally verify this theoretically explained effect underwater. It was also reported that the researchers plan to test similar interference effects with light waves instead of sound waves.