Outer and Middle Ears

Rosowski, John J.

doi:10.1007/978-1-4612-2700-7_6

Cited by 103 publications

(75 citation statements)

References 179 publications

(392 reference statements)

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“…Other lines of evidence supporting a role of the middle ear in determining hearing function are significant correlations between middle-ear dimensions and the low-and high-frequency limits of hearing in mammals (Rosowski & Graybeal 1991;Rosowski 1992Rosowski , 1994, and that simple manipulations of middleear structures can have profound influences on hearing function, e.g. the 15 dB increase in the sensitivity of the chinchilla ear to low-frequency sound when a hole is placed in the bullar wall (Figs 3 & 4).…”

Section: The Middle Ear and Auditory Frequency Responsementioning

confidence: 98%

“…One is the ideal transformer model of the ear, in which middle-ear sound transformation is reduced to the action of a coupled mechanical lever and an acoustical area ratio. This view has heuristic value for understanding the mechanisms of middle-ear action (Wever and Lawrence 1954;Dallos 1973;Rosowski 1994). The second is that the middle ear and external ear act as a filter that limits the sound energy available to the inner ear (Wever and Lawrence 1954;Dallos 1973;Zwislocki 1975;Rosowski et al 1986;Rosowski 1991a&b).…”

Section: The Middle Ear and Auditory Frequency Responsementioning

confidence: 99%

“…In support of the second view are reasonable matches between the frequency dependence of external-and middle-ear function with auditory thresholds in various animals (Dallos 1973;Zwislocki 1975;Khanna and Tonndorf 1978;Rosowski et al 1986; Rosowski 1991a&b;Puria et al 1997) at least to frequencies as high as 10000 Hz. Other lines of evidence supporting a role of the middle ear in determining hearing function are significant correlations between middle-ear dimensions and the low-and high-frequency limits of hearing in mammals (Rosowski & Graybeal 1991;Rosowski 1992Rosowski , 1994, and that simple manipulations of middleear structures can have profound influences on hearing function, e.g. the 15 dB increase in the sensitivity of the chinchilla ear to low-frequency sound when a hole is placed in the bullar wall (Figs 3 & 4).…”

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confidence: 98%

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Structures that contribute to middle-ear admittance in chinchilla

2006

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We describe measurements of middle-ear input admittance in chinchillas (Chinchilla lanigera) before and after various manipulations that define the contributions of different middle-ear components to function. The chinchilla's middle-ear air spaces have a large effect on the lowfrequency compliance of the middle ear, and removing the influences of these spaces reveals a highly admittant tympanic membrane and ossicular chain. Measurements of the admittance of the air spaces reveal that the high-degree of segmentation of these spaces has only a small effect on the admittance. Draining the cochlea further increases the middle-ear admittance at low frequencies and removes a low-frequency (less than 300 Hz) level dependence in the admittance. Spontaneous or sound-driven contractions of the middle-ear muscles in deeply anesthetized animals were associated with significant changes in middle-ear admittance. KeywordsMiddle-ear structure-function; Comparative Auditory Function INTRODUCTIONChinchillas (Chinchilla lanigera) are nocturnal foragers that lived in communal burrows and are native to the rocky slopes of the high Andes. However, wild chinchillas are endangered, having been over-hunted by humans for food and their fur, and preyed upon by European species introduced into their habitat. Captive chinchillas have been successfully bred in the USA and Russia over the last 80 years. Since the 1950s, chinchillas have become a common animal model in hearing and other research areas (Price 1953;Tibbitts and Hillemann 1959);Peters 1965;Henderson 1969;Lupien and McCay 1960; Bismark and Pfeiffer 1967;Trautwein & Helmboldt 1967;Strike and Seigneur 1969;Dallos 1970;Miller 1970).The high Andes is an open and arid environment and chinchillas show some adaptations that are similar to those seen in other animals adapted to open and arid areas including a few distinctive features of the middle ear:1. large middle-ear air spaces ( total volume ≥ 1.5 cc) that are segmented into multiple sub-cavities (Browning and Granish 1978; Vrettakkos et al. 1988).Corresponding Author: John J Rosowski, Email: John_Rosowski@meei.harvard.edu, Phone: 1 617 657 4237, Fax 1 617 720 4408. 2. large tympanic-membrane (TM) and ossicular dimensions for an animal of its size (Vrettakkos et al. 1988; Rosowski 1991a&b, 1994, and 3. increased mechanical sensitivity to low-frequency (f < 1000 Hz) acoustic stimuli relative to other animals with similar hearing ranges (Ruggero et al. 1990). NIH Public AccessWhen viewed in light of the relatively sensitive low-frequency auditory thresholds in this species (Fay 1988;Miller 1970), the chinchilla middle ear appears specialized for lowfrequency hearing. While preliminary acoustic admittance (Dear 1987) 1 , cochlear potential (Dallos 1970) and ossicular-motion measurements (Ruggero et al. 1990) are all consistent with this view, past studies have not determined which middle-ear structures contribute to the sensitivity to low-frequency sound.There is a history of work on other species specialized for arid climates,...

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Section: The Middle Ear and Auditory Frequency Responsementioning

confidence: 98%

Section: The Middle Ear and Auditory Frequency Responsementioning

confidence: 99%

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confidence: 98%

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Structures that contribute to middle-ear admittance in chinchilla

2006

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“…Outer ears with long and narrow dimensions should show a decrease in lowfrequency reception while ears that are wider or larger will be sensitive to low-as well as high-frequency sounds and will provide more directional cues at low frequencies (Rosowski, 1994). Although intuitively it might seem advantageous for all animals to maximize sensitivity to as wide a range of frequencies as possible, specialization might entail trade-offs.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…The ITR is often considered an ideal transformer ratio because it ignores the intrinsic impedance of the components of the auditory system itself (Dallos, 1973), and several researchers have found a lack of association between the ITR or its component ratios (e.g., areal convergence ratio) and measures of auditory sensitivity (Lay, 1972;Rosowski, 1994). However, it provides a useful starting point for analyzing middle ear function and continues to be used by investigators as a proxy for estimating middle ear performance (Webster and Webster, 1975;Hunt and Korth, 1980;Masali et al, 1992).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Primate auditory diversity and its influence on hearing performance

2004

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The auditory region contains numerous structures that have proven useful for phylogenetic classification at various taxonomic levels. However, little work has been done in primates relating differences in morphology to variations in hearing performance. This study documents anatomical and physiological distinctions within primates and begins to address the functional and evolutionary consequences of these and other auditory features. The dimensions of the outer ear (pinna) were measured in cadaveric specimens representing nearly every primate family and used to calculate a shape ratio (height/width). It was found that nonanthropoids have a significantly higher ratio than anthropoids, although the actual height was not found to differ. This indicates that most nonanthropoids have ears that are tall and narrow, whereas monkeys and apes are characterized by ears with more equal height and width dimensions. Eardrum area, stapedial footplate area, and ossicular lever arm lengths were measured in dried specimens to calculate an impedance transformer ratio. A distinction was found between anthropoids and strepsirrhines, with the latter group having a transformer ratio indicative of a higher percentage of acoustic energy transmission through the middle ear. Audiogram data were gathered from the literature to analyze hearing sensitivity and it was found that platyrrhines illustrate more low-frequency sensitivity than like-sized lorisoids. The effects of intraspecific variation on the audiogram results were also examined and were found to produce similar results as the analysis using species mean threshold values. Lastly, correlations between morphological and audiogram variables were examined. Several measures of hearing sensitivity were found to be correlated with pinna shape but correlations with middle ear transmission properties were weaker. In addition to using traditional statistical techniques, phylogenetic corrective methods were applied to address the problem of statistical nonindependence of the data and the results of both analyses are compared. These findings are discussed with respect to how sensory adaptations and phylogenetic history may be related to the current radiation of primates. Key words: primate hearing; outer ears; middle ears; audiogram; phylogenyPrimates express numerous modifications on the fundamental mammalian middle ear morphology and these differences have proven useful for phylogenetic classification at various taxonomic levels (MacPhee and Cartmill, 1986). Among extant strepsirrhines, most Malagasy primates are characterized by a free-floating tympanic ring surrounded by a single relatively large tympanic cavity while lorisoids have a tympanic ring that is fused to the lateral wall of a smaller tympanic cavity. Lorises appear to maintain a substantial effective cavity volume by having additional pneumatic spaces off of the epitympanic recess. Extant haplorhines are similar to lorises in possessing epitympanic sinuses (except tarsiers) (MacPhee and Cartmill, 1986) and a fused tym...

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Comparative Psychology of Audition

Moss

Carr

2003

Handbook of Psychology

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Many animal species use sound to orient in the environment, detect predators, and communicate with conspecifics. Auditory systems have evolved to enable these behaviors, permitting the detection, localization, and discrimination of acoustic events. This chapter provides an overview of auditory systems and behavior in a variety of animal species, including insects, amphibians, birds, and mammals. Emphasizing a comparative and evolutionary perspective, the chapter details features of the auditory pathway—from the ear to central structures involved in the processing of acoustic stimuli. Anatomical pathways and physiological response characteristics of neurons at different stages of the auditory pathway are described. The chapter also reviews behavioral measures of auditory function, emphasizing studies of absolute hearing sensitivity, frequency selectivity, temporal resolution, sound localization, and scene analysis. Comparisons of auditory system anatomy, physiology, and function across species reveal exquisite specializations but also many common principles across the animal kingdom.

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Outer and Middle Ears

Cited by 103 publications

References 179 publications

Structures that contribute to middle-ear admittance in chinchilla

Structures that contribute to middle-ear admittance in chinchilla

Primate auditory diversity and its influence on hearing performance

Comparative Psychology of Audition

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