Auditory Attention and Filters

Abstract

To survive, animals must navigate, find food, avoid predators, and reproduce; and many species survive based on their ability to communicate. All of these crucial behaviors allow animals to function in a crowded world of obstacles, objects, and other animals. Many of these objects vibrate and produce sound, and sound may be used to determine the sources of the sound and to serve as a basis for communication. Sounds produced by different sources are combined in one sound field that must be parsed into information that allows for the determination of the individual sources. This process begins at the level of the auditory receptor organ, but is primarily accomplished by processing of the peripheral code in the brain. Given the variety of sources that produce sound, the complexity of the world in which these sources exist, and the lack of peripheral receptors to analyze sound sources per se, determining the sources of sound presents a significant challenge for the auditory system. At present, not a great deal is known about how the auditory system deals with this challenge. This book reviews several topics that are likely relevant to enhance an understanding of the auditory system’s ability to determine sound sources. Yost, in Chapter 1, provides an overview of the volume and the issues that arise in considering sound source perception. Chapter 2, by Lufti, describes the properties of resonating sources, especially solids, and how the various properties of a resonating sound source (e.g., size, mass, tension) may affect sound source perception. In Chapter 3, Patterson, Smith, van Dinther, and Walters consider the standing-wave properties of sound sources, such as the vocal tract, and how the size of such resonators may determine the perception of the source. Chapter 4, by Demany and Semal, reviews much of the current knowledge about auditory memory, especially as it may relate to sound source perception. In addition to the importance of attending to one source or another to function in our everyday acoustic world, auditory attention may also play a direct role in aiding the auditory system in segregating one sound source from another. Chapter 5, by Hafter, Sarampalis, and Loui, reviews much of the literature related to auditory attention. In Chapter 6, by Kidd, Mason, Richards, Gallun, and Durlach, the topics of masking, especially energetic and informational masking, are reviewed as they relate to sound source perception. This is followed by Chapter 7, by Carylon and Gockel, in which the authors discuss how sources may be perceived and segregated based on a source’s fundamental frequency of vibration and its resulting harmonic structure or temporal and spectral regularity. A great deal is known about how differences in interaural arrival time and interaural level differences are used to locate the position of sound sources. Darwin (Chapter 8) considers the role spatial separation (especially interaural time and level differences) plays in sound source perception and segregation. In Chapter 9, Sheft discusses temporal patterns of sounds and how these patterns pertain to sound source perception. This is followed by Chapter 10, by Lotto and Sullivan, who consider the speech-perception literature that provides insights into processes that might be considered for a better understanding of sound source perception for any potential sound source. Finally, in Chapter 11, Fay reviews the growing body of literature on how animal subjects other than humans process sound from sources. Related chapters pertaining to other aspects of sound source perception can be found elsewhere in chapters from the Springer Handbook of Auditory Research series. Several chapters in Volume 15 (Integrative Functions in the Mammalian Auditory Pathway) relate to the questions of sound source perception, especially Chapter 9 (“Feature Detection in Auditory Cortex”) by Nelken. Lewis and Fay, in Volume 22 (Chapter 2), Evolution of the Vertebrate Auditory System,is a treatment of the acoustic variables that could play a role in sound source perception. Volume 24 (Pitch: Neural Coding and Perception) contains several chapters that relate to this topic, especially Chapter 8, by Darwin, on “Pitch and Auditory Grouping.” Volume 25 (Sound Source Localization) is a recent authoritative review of this topic. Volume 28 (Hearing and Sound Communication in Amphibians), and especially Chapter 11 on “Sound Processing in Real-World Environments,” by Feng and Schul, treats many aspects of sound source perception in amphibians.