HHHHHH: Free Universal Amplifiers

I like to listen to podcasts on my old phone in my old car. Without an aux input on my broken-down car radio, I can't run the podcasts through the car's speakers. I recently happened upon a way to amplify the volume from the little outboard speaker on the phone: put it in the cupholder, speaker side down. I'm no sound engineer, but it makes sense that the sound would resonate off the sides of the solid cupholder and be louder. This technique seems to work better with male voices than with female voices for some reason. The sound gets muffled slightly, but it's definitely amplified. It's at least loud enough that I can listen hands-free more like listening to the radio in the car. Depending on the audio levels of the podcast, it works everywhere but on noisy highways. Sample video below; sorry for the blurriness.

The same technique works in the kitchen with a bowl as amplifier. Who needs complicated docking or transmitter solutions when you have cupholders and bowls around?