sonar

Dolphins swim off the coast.
Very loud, repeated blasts of sonar
can cause a dolphin to temporarily lose its hearing.

blast	ひと吹き、攻撃
temporarily	一時的に

reference
http://news.yahoo.com/nphotos/Science-Photos/ss/832/im:/090407/photos_sc_afp/e55bab1fcc6c4e5c7c518d167e9874f7/