The "gPod," a phallic-shaped vibrator, is designed to respond automatically to sounds picked up by an accompanying handset, which can plug into anything from a telephone to a music player to a television.
The 25,000-yen (200-dollar) gPod was one of a number of toys that went on public view Friday at Japan's first-ever sex toy expo in suburban Tokyo.
"You can use it in many ways, for example hooking it up to your mobile phone," said Ichiro Kameda, the machine's inventor.
"The dildo vibrates through the same waves as a voice. So one of the ideas is that you can use it here in Tokyo when your boyfriend in New York is talking to you on the phone."
Kameda said he had spent four years trying to design a product when he hit upon the concept. He declined to say how the idea came to him.
Nearly 160 companies or groups are exhibiting products and services at the three-day Adult Treasure Expo 2007, including sex toys, sex machines, costumes and videos.