Constructing and disrupting listeners' models of auditory space.
ABSTRACT A major problem for an auditory system exposed to sound in a reverberant environment is to distinguish reflections from true sound sources. Previous research indicates that the process of recognizing reflections is malleable from moment to moment. Three experiments report how ongoing input can prevent or disrupt the fusion of the delayed sound with the direct sound, a necessary component of the precedence effect. The buildup of fusion can be disrupted by presenting stimuli in alternation that simulate different reflecting surfaces. If buildup of fusion is accomplished first and then followed by an aberrant configuration, breakdown of the precedence effect occurs but it depends on the duration of the new sound configuration. The Djelani and Blauert (2001) finding that a brief disruption has no effect on fusion was confirmed; however, it was found that a more lengthy disruption produces breakdown.
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ABSTRACT: To gain information from complex auditory scenes, it is necessary to determine which of the many loudness, pitch, and timbre changes originate from a single source. Grouping sound into sources based on spatial information is complicated by reverberant energy bouncing off multiple surfaces and reaching the ears from directions other than the source's location. The ability to localize sounds despite these echoes has been explored with the precedence effect: Identical sounds presented from two locations with a short stimulus onset asynchrony (e.g., 1-5 ms) are perceived as a single source with a location dominated by the lead sound. Importantly, echo thresholds, the shortest onset asynchrony at which a listener reports hearing the lag sound as a separate source about half of the time, can be manipulated by presenting sound pairs in contexts. Event-related brain potentials elicited by physically identical sounds in contexts that resulted in listeners reporting either one or two sources were compared. Sound pairs perceived as two sources elicited a larger anterior negativity 100-250 ms after onset, previously termed the object-related negativity, and a larger posterior positivity 250-500 ms. These results indicate that the models of room acoustics listeners form based on recent experience with the spatiotemporal properties of sound modulate perceptual as well as later higher-level processing.The Journal of the Acoustical Society of America 01/2011; 129(1):301-9. · 1.65 Impact Factor
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ABSTRACT: La capacidad para percibir si el sonido que se escucha proviene desde la izquierda o derecha, arriba o abajo, detrás o adelante y qué tan cerca o lejos se encuentra la fuente sonora es de importancia capital tanto para animales como para seres humanos. La investigación sistemática sobre los aspectos evolutivos involucrados en el desarrollo de esta habilidad comenzó recién en la década del 80. El propósito de este trabajo es realizar una revisión de las principales investigaciones sobre el desarrollo de la habilidad para localizar sonidos directos y reflejados en neonatos y niños pequeños. Se discuten las principales hipótesis explicativas de los cambios evolutivos observados en esta habilidad y los tópicos que aún desafían a los expertos.Revista latinoamericana de psicología 01/2009; · 0.64 Impact Factor
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ABSTRACT: Reflected sounds are often treated as an acoustic problem because they produce false localization cues and decrease speech intelligibility. However, their properties are shaped by the acoustic properties of the environment and therefore are a potential source of information about that environment. The objective of this study was to determine whether information carried by reflected sounds can be used by listeners to enhance their awareness of their auditory environment. Twelve listeners participated in two auditory training tasks in which they learned to identify three environments based on a limited subset of sounds and then were tested to determine whether they could transfer that learning to new, unfamiliar sounds. Results showed that significant learning occurred despite the task difficulty. An analysis of stimulus attributes suggests that it is easiest to learn to identify reflected sound when it occurs in sounds with longer decay times and broadly distributed dominant spectral components.Military Psychology - MIL PSYCHOL. 01/2009; 22(1):24-40.