While many iPhone software developers try to balance utility and entertainment value, Studio Six Digital has taken a decidedly more serious approach with apps that cater to the engineering side of music production. One that’s very handy is SPL (V. 1.4, $5.99), which is a full-featured decibel meter that uses the iPhone’s built-in mic or an external one. Studio Six Digital also makes the lower-priced SPL Meter (V. 1, $0.99), which is designed to emulate a familiar, budget-priced, analog decibel meter from a popular electronics-store chain. Read the rest of this entry »