The speakers installed in laptops / tablet pc's are often very poor for an application like NextUp Talker. One way to solve the problem is to use external speakers. For external speakers, we need something small and light enough to carry around, and also produce sufficent volume and sound quality.
Here's a recommendation from one user:
JLab Audio BFB01 B-Flex Hi-Fi Stereo USB Laptop Speaker
These speakers are small (just one piece) and usb powered. Search on Jlab Audio BFB01 and you'll find places to buy online.
Any other suggestions / recommendations?