There's also Stephen Smith's "The Scientist and Engineer's Guide to Digital Signal Processing", quite minimal in its use of mathematics until the last four chapters, but it has some very nice intuitive and easy to follow explanations of convolution, the discrete Fourier transform, FIR/IIR filters, plus many chapters devoted to uses of DSP; e.g., neural networks, image processing, etc. An easy read, but it will leave you wanting more, so you'll need to move up to Lyons' book when you're done. I think ONLY AFTER one has fully mastered Lyons should one attempt Oppenheim and Schafer's texts (I have their 1975 work "Digital Signal Processing", a classic in/of itself; very concise, but requires a strong familiarity with advanced calculus and complex variable theory) to put you at the expert level of DSP.
Sound is emitted from the edges of the cone also and the frequency changes the wave lengths as well. This time alignment can't be that important. Maybe only at the crossover point with sharp slope ?
