Hi all, The free Seadragon program allows you to emit underwater whistles and it recognizes underwater whistles. All you need is a laptop with Java SE 5 Runtime Environment (JRE) and two hydrophones (actually one hydrophone and one projector transducer). Java SE 5 JRE for Windows is free from http://java.com (Sun Microsystems). An Apple version of the JRE version 5 is included in recent models of Macintosh computers and older Macintoshes can be upgraded with the free JRE from Apple. The installation of the current version on a Macintosh requires some technical expertise on the part of the user. I am hoping to simplify this installation eventually. Seadragon is open source: CPL, Common Public License. The source code is included in the download zip file. We are not a commercial organization. I am a single individual. I wrote the software. I only provide the free software and you must obtain your equipment from your favorite suppliers. Download: http://sourceforge.net/projects/c2h/ User guide: http://leafyseadragon.blogspot.com/2006/01/seadragon-2-user-guide-april-2006... You design your whistles in an xml file (using a text editor such as Notepad) prior to starting the application. Sample whistles are included. It is recommended to test your whistles in air first. For testing in air, I use headphones with a microphone and I do not wear the headphone during the tests. The current version is limited to whistles between 1 kHz and 10 kHz. To emit whistles, you type the names of the whistles that you want to emit. The software continuously listens for whistles and when it recognizes whistles, it writes their names (which are artificial identifiers) on the screen. Newly acquired whistles are given a new unique name, which can be changed prior to the next session. The user guide contains more details. The system works somewhat like an instant messaging application for underwater whistles. The system does not attempt to interpret the whistles that it emits and acquires. The system writes the session data in xml files for later analysis and for exchange with other researchers. The current version is an early one meant to be used for exploratory work, prior to planning your research project, and for deciding whether such a tool would be advantageous for furthering progress in your scientific areas of interests. The software is expected to be improved based on the needs of its users. It has not yet been used with dolphins at sea, as far as I know. Please use safe underwater and in-air sound pressure levels, and respect the laws and regulations that apply to the cetaceans in your location. For example, US citizens anywhere may be required to obey the US National Marine Fisheries Services' regulations for dolphins and these regulations may require that US citizens acquire a permit in order to use Seadragon in any waters. Other countries may have different regulations for the use of devices emitting underwater sounds near cetaceans. This is a very inexpensive opportunity for anyone who wants to try to experiment with dolphins using whistles. If you do use Seadragon at sea, it would be great if you would let us know about it. Any feedback would be appreciated. serge masse montreal, canada