Edition makes the difference!
The more recent the edition, the more mathematical and sophisticated the material becomes, reflecting more modern approaches to the subject. 1st and 2nd edition are good for the casual and curious inquiry, the 3rd and beyond editions (after Kinsler's death) begin the heavier topics. Also, the 3rd edition omits ultrasonic and sonar transducers, but updates absorption, underwater and architetural acoustics, and adds an environmental acoustics chapter. Any interested person can understand the main concepts and pick up the advanced topics as their comprehension increases. Well worth the investment.