boxes from the malaysian airlines plane. interestingly they were heard outside the search zone. another acoustic event was also detected by the australian ship ocean shield about 300 miles away. so i go now to my panel. paul ginsburg is an audio expert. and then paul, what are the words acoustic event mean to you? >> i was wondering why they use that term. i assume it means they weren't sure. that there was something that could or could not have been the pinger. it may have been distorted as others have said by the propagation through the water, the variation in speed of the sound between the pinger and the receiver. and it may have been slightly off frequency. it may not have had all the characteristics of what the pinger signal should have. or it may have had the characteristics but they were distorted so they did not want