Communication Acoustics: An Introduction to Speech, Audio and Psychoacoustics

Introduction

Efficient use of sensory functions and communication has been one of the most important factors in the evolution and survival of animals in nature. Especially for the highest forms of evolution, vision and hearing are the two main modalities to support this view in a complementary way. Visual information, based on the laws of optics, reflects the environment in a geometrically appropriate and reliable manner, while auditory sensing and perception, based on the laws of acoustics, are less dependent on physical constraints such as obstacles between an observer and objects to be perceived. Vision often dominates audition, especially if an object is clearly visible or moving, while hearing may capture important information even when there are no perceivable visual events. Sensory integration, i.e., fusion of information from different modalities into a coherent percept, is characteristic of living species. Only when senses provide conflicting cues must they compete for contribution to the final percept.

Two main ways of utilizing the auditory sense are to sense orientation in the environment and for communication between subjects. The former activity can be found among early phases of animal evolution. As an example, the sound events shown in Figure I.1 bring information to the subject about the surroundings. The sounds caused by the shoes of the horse imply the type of terrain, the wind sounds bring information about the weather, and the sounds caused by animals, even ...