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Margaret H. Searcy

Bio: Margaret H. Searcy is an academic researcher from Rockefeller University. The author has contributed to research in topics: Sparrow & Masking (art). The author has an hindex of 10, co-authored 11 publications receiving 413 citations.

Papers
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Journal ArticleDOI
TL;DR: Results are the 1st direct evidence for a sensory component in the process of selective vocal learning in birds.
Abstract: The cardiac orienting response to species-specific songs was measured in young swamp sparrows and song sparrows. Swamp sparrows respond with significantly greater deceleration to conspecific songs than to songs of the sympatric song sparrow. This discriminatory ability is operating during the sensitive period for song learning and is evident upon initial exposures to conspecific song. These results are the 1st direct evidence for a sensory component in the process of selective vocal learning in birds.

158 citations

Journal ArticleDOI
TL;DR: Parakeets were tested for the ability to detect sinusoidal amplitude modulation of broad band noise and results are somewhat different from amplitude modulation functions in humans suggesting different degrees of temporal resolving power in birds and humans.
Abstract: Parakeets were tested for the ability to detect sinusoidal amplitude modulation of broad band noise. Instrumental avoidance conditioning and a psychophysical modified method of limits procedure were used to measure the threshold for detecting amplitude modulation at 10 modulation frequencies between 2 and 2,048 Hz. Below about 40 Hz, modulation threshold is independent of modulation rate and noise level. Above 40 Hz, modulation threshold decreases with modulation frequency at the rate of 3 dB/ octave. These results are somewhat different from amplitude modulation functions in humans suggesting different degrees of temporal resolving power in birds and humans. Thresholds for changes in modulation rate are 1–2 orders of magnitude higher than pure tone frequency difference limens.

59 citations

Journal ArticleDOI
TL;DR: Thresholds for two complex natural vocalizations of the budgerigar are similar to those of pure tones of equivalent duration, and at very short durations there were differences in the integration of tone and noise signals.
Abstract: Avoidance conditioning and a modified method of limits psychophysical procedure were used to study temporal integration of tone and noise signals in the budgerigar (Melopsittacus undulatus). Integration of both tone and noise signals can be described by a negative exponential function with a time constant of about 200 ms. At very short durations there were differences in the integration of tone and noise signals. These data are similar to those reported for a number of other vertebrates, including man. Thresholds for two complex natural vocalizations of the budgerigar are similar to those of pure tones of equivalent duration.

54 citations

Journal ArticleDOI
TL;DR: The ability to sing multiple song types may aid males in stimulating females to come into reproductive condition and then copulate, and this result occurred because females habituated to the repeated presentation of a single song type, and showed a recovery in response when song types were switched.
Abstract: Male and femal swamp sparrows (Melospiza georgiana) were tested for differential reaction to four acoustically distinct swamp sparrow song types. We tested males by playing bouts of single song types from speakers placed on male territories. Males gave the same kinds of aggressive responses to each of the four song types, and there were no quantitative differences in the strengths of the responses to the different types. In the experiments with females, we played songs to captive female swamp sparrows previously treated with estradiol, and measured response in terms of copulation solicitation display. Females displayed in response to all four song types, and again there were no quantitative differences in the strength of response to the different types. We conclude that different swamp sparrow song types do not convey different messages to either male or female listeners. Although the identity of the particular song type presented was unimportant, the number of types presented was important, at least to females. Females responded more strongly overall to bouts of four song types than to bouts of single song types. This result occurred because females habituated to the repeated presentation of a single song type, and showed a recovery in response when song types were switched. We conclude that the ability to sing multiple song types may aid males in stimulating females to come into reproductive condition and then copulate.

46 citations

01 Jan 1979
TL;DR: In this article, the intensity difference limens obtained for the parakeet using amplitude modulated pure tones indicate a Weber fraction (ΔI/I) of about 23 to.43 over a range of five test frequencies.
Abstract: Intensity difference limens obtained for the parakeet using amplitude modulated pure tones indicate a Weber fraction (ΔI/I) of about.23 to.43 over a range of five test frequencies. These values are lower than previous measures of intensity resolving power in this species and are in perfect agreement with previously published critical ratio and critical band data for the parakeet.

21 citations


Cited by
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Journal ArticleDOI
TL;DR: Human speech and birdsong have numerous parallels, with striking similarities in how sensory experience is internalized and used to shape vocal outputs, and how learning is enhanced during a critical period of development.
Abstract: Human speech and birdsong have numerous parallels. Both humans and songbirds learn their complex vocalizations early in life, exhibiting a strong dependence on hearing the adults they will imitate, as well as themselves as they practice, and a waning of this dependence as they mature. Innate predispositions for perceiving and learning the correct sounds exist in both groups, although more evidence of innate descriptions of species-specific signals exists in songbirds, where numerous species of vocal learners have been compared. Humans also share with songbirds an early phase of learning that is primarily perceptual, which then serves to guide later vocal production. Both humans and songbirds have evolved a complex hierarchy of specialized forebrain areas in which motor and auditory centers interact closely, and which control the lower vocal motor areas also found in nonlearners. In both these vocal learners, however, how auditory feedback of self is processed in these brain areas is surprisingly unclear. Finally, humans and songbirds have similar critical periods for vocal learning, with a much greater ability to learn early in life. In both groups, the capacity for late vocal learning may be decreased by the act of learning itself, as well as by biological factors such as the hormones of puberty. Although some features of birdsong and speech are clearly not analogous, such as the capacity of language for meaning, abstraction, and flexible associations, there are striking similarities in how sensory experience is internalized and used to shape vocal outputs, and how learning is enhanced during a critical period of development. Similar neural mechanisms may therefore be involved.

1,519 citations

Book ChapterDOI
TL;DR: This chapter reviews recent advancements in studies of vocal adaptations to interference by background noise and relates these to fundamental issues in sound perception in animals and humans.
Abstract: Publisher Summary Environmental noise can affect acoustic communication through limiting the broadcast area, or active space, of a signal by decreasing signal-to-noise ratios at the position of the receiver. At the same time, noise is ubiquitous in all habitats and is, therefore, likely to disturb animals, as well as humans, under many circumstances. However, both animals and humans have evolved diverse solutions to the background noise problem, and this chapter reviews recent advancements in studies of vocal adaptations to interference by background noise and relate these to fundamental issues in sound perception. The chapter starts with the discussion of sender's side by considering potential evolutionary shaping of species-specific signal characteristics and individual short‐term adjustments of signal features. Subsequently, it focuses on the receivers of signals and reviews their sensory capacities for signal detection, recognition, and discrimination and relates these issues to auditory scene analysis and the ecological concept of signal space. The data from studies on insects, anurans, birds, and mammals, including humans, and to a lesser extent available work on fish and reptiles is also discussed in the chapter.

845 citations

Journal ArticleDOI
16 May 2002-Nature
TL;DR: With the discovery and investigation of discrete brain structures required for singing, songbirds are providing insights into neural mechanisms of learning and are addressing such basic issues in neuroscience as perceptual and sensorimotor learning, developmental regulation of plasticity, and the control and function of adult neurogenesis.
Abstract: Bird fanciers have known for centuries that songbirds learn their songs. This learning has striking parallels to speech acquisition: like humans, birds must hear the sounds of adults during a sensitive period, and must hear their own voice while learning to vocalize. With the discovery and investigation of discrete brain structures required for singing, songbirds are now providing insights into neural mechanisms of learning. Aided by a wealth of behavioural observations and species diversity, studies in songbirds are addressing such basic issues in neuroscience as perceptual and sensorimotor learning, developmental regulation of plasticity, and the control and function of adult neurogenesis.

517 citations

Journal ArticleDOI
TL;DR: The present review summarizes the present knowledge about representation and processing of periodic signals, from the cochlea to the cortex in mammals, and in homologous or analogous anatomical structures as far as these exist and have been investigated in other animals.

471 citations