The two companies are part of a new wave of firms aimed at giving email and the popular Internet instant text messaging applications a voice component, so that surfers can talk to each other live on the Web.
The mostly stock transaction is valued at about $125 million, the HearMe executives said.
The merger will give HearMe technology that will allow its subscribers to connect calls to ordinary offline phones, instead of limiting them to the Net. AudioTalk has focused its technology on the corporate market.
"This was something we were going to have to build, and they already had it," Paul Matteucci, HearMe's chief executive, said.
The Net voice chat business is still in its infancy, with a wide range of companies competing for slightly different slices of a still-fuzzy market. HearMe is one of the largest consumer voice chat companies on the Web.
HearMe and competitor FireTalk Communications have each created software applications that allow visitors to individual Web pages to talk to each other, or to download small applications that serve much like a voice-focused ICQ service, America Online's instant text messaging service. Net telephony companies such as DialPad or Net2Phone focus specifically on replacing traditional telephone companies' offerings with cheaper Web-based services.
Other firms such as AudioTalk or Lipstream Networks have focused more heavily on the business market, selling their services to clients such as e-commerce companies that wanted to add live voice customer support services to their Web sites. AudioTalk in particular has developed technology that allows communication between computers, or between a computer and an ordinary telephone.