Tutorials and Topics - Peabody Computer Music

Delay emulates reflectionTutorial 28: Processing—Delay lines with feedbackYou can delay a signal for a specific amount of time using the tapin~ and tapout~ objects.The tapin~ object is a continually updated buffer that stores the most recent signal it hasreceived, and tapout~ accesses that buffer at one or more specific points in the past.Delaying a signal with tapin~ and tapout~Combining a sound with a delayed version of itself is a simple way of emulating a soundwave reflecting off of a wall before reaching our ears; we hear the direct sound followedclosely by the reflected sound. In the real world some of the sound energy is actuallyabsorbed by the reflecting wall, and we can emulate that fact by reducing the amplitude ofthe delayed sound, as shown in the following example.Scaling the amplitude of a delayed signal, to emulate absorptionTechnical detail: Different materials absorb sound to varying degrees, andmost materials absorb sound in a way that is frequency-dependent. Ingeneral, high frequencies get absorbed more than low frequencies. Thatfact is being ignored here.223