Dr. Adam Frankel published an article entitled, “Gray whales hear and respond to signals from a 21-25 kHz active sonar” in Marine Mammal Science. This article discusses research funded by the Office of Naval Research. Southbound gray whales off California were presented with 21-25 kHz sound sweeps. A research vessel moored in the migration path, transmitted the sweeps half the time, and was silent the other half. Whales had no overt or obvious response to the sound. However later statistical analyses showed that the whales slightly avoided the sound. This response demonstrates that gray whales can hear sounds in the 21-25 kHz range. These findings extend our understanding of baleen whale hearing.