I have to admit that I was a skeptic about the SoundJaw (US$20), a small plastic device that was one of our Kickstarter entries a while back and the brainchild of Coloradan Matt McLachlan. The idea is that it clips onto the bottom of an iPad 2 where the speaker holes are located and forces the sound forward (towards the user) to increase the volume that you hear. I'm happy to say that I was wrong, and the SoundJaw does actually pump up the volume of sound emitted from an iPad 2.
To test the SoundJaw scientifically and not depend on my hearing, I purchased the Decibel Meter Pro app ($0.99) from Performance Audio LLC and installed it on my iPhone 4. What I was interested in was watching the peak loudness of a song being played on my iPad 2 and measuring the decibel level with and without the SoundJaw. To make sure that the microphone was in the same exact location both times, I used a Glif ($20) and a tripod to hold my iPhone above the iPad 2.
Playing the same song at medium volume on the iPad 2 with the SoundJaw attached, the peak level was 68 dB, compared to 65 dB without the SoundJaw. Frankly, it didn't sound any louder to me. When I cranked the volume all the way up on the iPad 2, the result was more dramatic -- 79 dB with the SoundJaw, 75 dB without, and I could perceive that the SoundJaw made my iPad sound louder.
OK, you may be saying "Well, that's only a difference of 3 or 4 dB. Big deal." What you need to remember is that dB is a logarithmic quantity. Without going into a lot of craziness about psychoacoustics, perceived loudness, and Sound Pressure Level, let's just say that while 3 dB is a "barely perceptible change" in loudness, the human ear definitely perceives a 4 dB increase. A 10 dB SPL difference is about "twice as loud," while a 4 dB increase is perceived as about 30 percent louder.
The SoundJaw is a nice way to improve loudness from your iPad 2 without resorting to a powered dock or mobile speakers. The SoundJaw currently comes in black and white to match the two iPad 2 colors, doesn't interfere with use of the Smart Cover, and like Nigel Tufnel's amps, it'll make your iPad 2 "go to eleven."