I have a hearing problem. At home I use wireless headphones. No problem. But when I travel, hotels and such generally do not have outlets. Therefore, what I need is a microphone type device with headphone which does not need outlets. Radio Shack in the United States sells such a device, but I tried it and it did not increase the volume at all. I do not want to turn up the volume too loud and irritate the people in the next room. Any ideas?