This chapter presents some interesting applications of basic signal processing including a historical description of how electronic sound effects emerge in music and movie recordings. The performance space provides a necessary enhancement of audio signals meant to be heard by a group of people whether it is governmental communication, theater performing arts, music performance, or religious celebration. Even a long tunnel can produce a smooth diffuse reverberation signal when the flutter echoes are controlled by absorption near the source and receiver. The “musical” instrument is the “open-reel magnetic tape recorder” where several were put together in tandem to allow a controllable time-delayed signal to be produced. Mixing the delayed signal back into the original recorded signal is what produced all the interesting and artful sound effects. For signal processing and control systems where digital outputs are to be converted back to analog signals, the process of signal reconstruction is important to the fidelity of the total system.