Behavioural audiograms from the bat,Rhinolophus ferrumequinum

Long, Glenis R.; Schnitzler, Hans‐Ulrich

doi:10.1007/bf00614531

Cited by 124 publications

(66 citation statements)

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“…The data from this study and the study of Schuller (1980) confirm that this is also true in Rhinolophus rouxi. Although our data and Schuller's are consistent in revealing that the resting frequencies are slightly below the second harmonic sensitivity peak of the ear, it should be noted that Long and Schnitzler (1975) studied behavioral audiograms in Rhinolophus ferrurnequinurn and in two of the three animals the resting frequencies were almost 800 Hz higher than the sharply tuned, second harmonic sensitivity peak of the audiogram. In the third animal the resting frequency was slightly below the threshold minimum of the behavioral audiogram and thus only in this case were the findings similar to ours.…”

Section: Discussionsupporting

confidence: 83%

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A comparative study of the physiological properties of the inner ear in Doppler shift compensating bats (Rhinolophus rouxi andPteronotus parnellii)

1985

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Summary. Cochlear microphonic (CM) and evoked neural (N-I) potentials were studied in two species of Doppler shift compensating bats with the aid of electrodes chronically implanted in the scala tympani. Potentials were recorded from animals fully recovered from the effects of anesthesia and surgery. In Pteronotus p. parnellii and Rhinolophus rouxi the CM amplitude showed a narrow band, high amplitude peak at a frequency about 200 Hz above the resting frequency of each species. In Pteronotus the peak was 25-35 dB higher in amplitude than the general CM level below or above the frequency of the amplitude peak. In Rhinolophus the amplitude peak was only a few dB above the general CM level but it was prominent because of a sharp null in a narrow band of frequencies just below the peak. The amplitude peak and the null were markedly affected by body temperature and anesthesia. In Pteronotus high amplitude CM potentials were produced by resonance, and stimulated cochlear emissions were prominent in Pteronotus but they were not observed in Rhinolophus. In Pteronotus the resonance was indicated by a CM afterpotential that occurred after brief tone pulses. The resonance was not affected by the addition of a terminal FM to the stimulus and when the ear was stimulated with broadband noise it resulted in a continual state of resonance. Rapid, 180 degree phase shifts in the CM were observed when the stimulus frequency swept through the frequency of the CM amplitude peak in Pteronotus and the frequency of the CM null in Rhinolophus. These data indicate marked differences in the physiological properties of the cochlea and in the mech-

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Section: Discussionsupporting

confidence: 83%

“…1980(Henson etal. , 1983Long and Schnitzler 1975;Schnitzler et al 1976;Pollak et al 1979); (3) a change in the tuning properties of the ear in response to changes in body temperature and/or to the administration of anesthetic drugs ; (4) a remarkable state of CM resonance in Pteronotus (Suga and Jen 1977;Suga etal. 1975;Henson etal.…”

Section: Discussionmentioning

confidence: 99%

A comparative study of the physiological properties of the inner ear in Doppler shift compensating bats (Rhinolophus rouxi andPteronotus parnellii)

1985

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“…Whereas the other species illustrated so far had relatively little variation in sensitivity in the midrange where hearing is best, these species have a slight W-shape to their audiograms with good hearing near 2 kHz and 8 kHz, but less sensitivity around 4 kHz. This is often characterized as two peaks of sensitivity, with various functions attributed to the upper peak such as communication (often specified as mother-infant communication) or echolocation in the case of bats (Long and Schnitzler, 1975;Bohn et al, 2001;Sterbing, 2002). However, the shape can also be characterized as a region of reduced sensitivity (here around 4 kHz) in an otherwise smooth audiogram.…”

Section: Old World and New World Monkeysmentioning

confidence: 99%

Primate hearing from a mammalian perspective

2004

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This review discusses hearing performance in primates and selective pressures that may influence it. The hearing sensitivity and sound-localization abilities of primates, as indicated by behavioral tests, are reviewed and compared to hearing and sound localization among mammals in general. Primates fit the mammalian pattern with small species hearing higher frequencies than larger species in order to use spectral/intensity cues for sound localization. In this broader comparative context, the restricted highfrequency hearing of humans is not unusual. All of the primates tested so far are able to hear frequencies below 125 Hz, placing them among the majority of mammals. Sound-localization acuity has been determined for only three primates, and here also they have relatively good localization acuity (with a minimum audible angle roughly similar to other mammals such as cats, pigs, and opossums). This is in keeping with the pattern among mammals in general, in which species with narrow fields of best vision, such as a fovea, are better localizers than those with broad fields of best vision. Multiple lines of evidence support the view that sound localization is the selective pressure on smaller primates and on other mammals with short interaural distances for hearing high frequencies. © 2004 Wiley-Liss, Inc. Key words: audiogram; primates; mammals; auditionThis is a review of the hearing of primates and the selective pressures involved in the evolution of mammalian hearing. Only behavioral tests of hearing are considered because it is the behavior of whole animals, not the mechanisms that might underlie it, that is subject to selective pressures. The responses of individual neurons and small groups of neurons may be relevant to how primates and other animals hear as they do, but not why. Similarly, morphological differences in the middle and inner ear are only alluded to as they provide mechanisms to support hearing; a good review of this topic can be found in Nummela (1995). Different mechanisms may be used to achieve similar abilities and do little to explain the origin of different hearing abilities in different species.The earliest comparative studies of hearing were conducted by Francis Galton in the late 1800s. By observing the natural responses of different species to unexpected high-pitched whistles, Galton discovered that cats can hear higher than humans and that humans lose their high-frequency hearing as they get older. However, he also thought that small dogs could hear high frequencies but that big dogs could not. We now know that large and small dogs all hear high frequencies (Heffner HE, 1983), but that big dogs do not necessarily respond to them, perhaps because high-pitched sounds are not as likely to signal danger to a large animal as are low-pitched sounds. Think of grass rustling as a mouse scurries through it compared to the thud of a branch broken by a buffalo. So, for the purposes of comparing hearing abilities across species, data were only considered if they were based on hearing test...

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“…In addition, the bats' large hearing range of some 100 kHz (26) (Fig. 1A) allows one to determine the role of how masking of different frequency bands affects their echolocation behavior.…”

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confidence: 99%

Ambient noise induces independent shifts in call frequency and amplitude within the Lombard effect in echolocating bats

Hage

Jiang

Berquist

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

125

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The Lombard effect, an involuntary rise in call amplitude in response to masking ambient noise, represents one of the most efficient mechanisms to optimize signal-to-noise ratio. The Lombard effect occurs in birds and mammals, including humans, and is often associated with several other vocal changes, such as call frequency and duration. Most studies, however, have focused on noisedependent changes in call amplitude. It is therefore still largely unknown how the adaptive changes in call amplitude relate to associated vocal changes such as frequency shifts, how the underlying mechanisms are linked, and if auditory feedback from the changing vocal output is needed. Here, we examined the Lombard effect and the associated changes in call frequency in a highly vocal mammal, echolocating horseshoe bats. We analyzed how bandpassfiltered noise (BFN; bandwidth 20 kHz) affected their echolocation behavior when BFN was centered on different frequencies within their hearing range. Call amplitudes increased only when BFN was centered on the dominant frequency component of the bats' calls. In contrast, call frequencies increased for all but one BFN center frequency tested. Both amplitude and frequency rises were extremely fast and occurred in the first call uttered after noise onset, suggesting that no auditory feedback was required. The different effects that varying the BFN center frequency had on amplitude and frequency rises indicate different neural circuits and/or mechanisms underlying these changes.A ny transmission of signals between sender and receiver faces the challenge of being subjected to masking by noise. For acoustic signals, for example, animals have evolved several strategies that aid in increasing the signal-to-noise ratio, thus facilitating signal transmission. One of the most efficient mechanisms is the socalled Lombard effect, i.e., the involuntary rise in call amplitude in response to masking ambient noise (1). This effect was first described in human communication a century ago (2) and has since been found in several species of birds (3-11) and various mammals (12-17), including bats (18). In human speech, several vocal changes, such as a rise in fundamental frequency (19) or lengthening in word duration (20), are often accompanied with the Lombard effect; combined, these changes are referred to as Lombard speech (21). Vocal changes associated with the Lombard effect have rarely been analyzed in animal species. So far, noisedependent changes in call frequency have been observed in birds (8,11,22), and changes in call duration in birds and monkeys (8,12).Most animal studies, however, have focused on noise-dependent changes in call amplitude and do not examine other possible vocal changes (2-5, 7, 9, 10, 15-17). It is therefore still largely unknown how the adaptive changes in call amplitude relate to frequency shifts or call elongation and how the underlying mechanisms are linked. It is also unknown if auditory feedback from the changing vocal output is needed to drive the Lombard effect in general.Over...

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Behavioural audiograms from the bat,Rhinolophus ferrumequinum

Cited by 124 publications

References 10 publications

A comparative study of the physiological properties of the inner ear in Doppler shift compensating bats (Rhinolophus rouxi andPteronotus parnellii)

A comparative study of the physiological properties of the inner ear in Doppler shift compensating bats (Rhinolophus rouxi andPteronotus parnellii)

Primate hearing from a mammalian perspective

Ambient noise induces independent shifts in call frequency and amplitude within the Lombard effect in echolocating bats

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