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Dec 1977

Volume 62, Issue S1, pp. S1-S102

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back to top Session KK. Physiological Acoustics IV: Auditory Mechanisms and Behavior (Poster Session)
Poster Papers
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Frequency response of the eardrums of some submammalian vertebrates (A)

Anne J. M. Moffat and Robert R. Capranica

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S85-S85 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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A laser light scattering interferometer was used to measure the amplitudes of sound induced vibrations of the tympana of two amphibian (Bufo americanus and Hyla cinerea) and one reptilian (Chrysemys scripta elegans) species. The maximum amplitude varied somewhat across species but was on the order of several hundred Ångstroms for a stimulus intensity of 90 dB SPL. In Bufo americanus the vibration amplitude is fairly constant to about 1.75 kHz then decreases at a rate of 21 dB/octave whereas in Hyla cinerea the roll off begins above 2.5 kHz and has a slope of between 14 and 22 dB/octave. In Chrysemys scripta elegans the vibration amplitude increases up to 500 Hz, drops off slowly (6.5–11 dB/octave) between 650 and 1250 Hz then more steeply (8.5–15 dB/octave) above 1250 Hz. In each species the frequency at which the vibration amplitude starts to decrease is correlated with the highest best excitatory frequency found in eighth nerve fibers, suggesting that the upper frequency of hearing is limited by the middle ear. In the amphibian species the displacement of the center of the tympanum, where the extracolumella attaches, is less than that of the free membrane area surrounding it suggesting that this free membrane acts as a conical level and contributes to driving the middle ear ossicles. [Work supported by NSF.]
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The cochlea of the bat, Pteronotus p. parnellii (A)

M. M. Henson, O. W. Henson, Jr., and D. B. Jenkins

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S85-S85 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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The highly specialized ear of the bat, Pteronotus parnellii parnellii, has been studied with electrophysiological and anatomical techniques. The cochlea is wide (4.5 mm) and has large round window and perilymphatic duct openings through which many structures can be approached. Within the large basal turn there is marked variation in nerve fiber density and the lining of the scala tympani is greatly thickened. Also in the basal turn the perilymphatic spaces and stria vascularis are enlarged in certain regions. In some parts of the cochlea the spiral ganglion cells are located in the internal auditory meatus rather than in the osseous spiral lamina. The hair cells and supportive cells generally resemble those of other mammals although the first space of Nuel is exceptionally large. These and other features will be depicted in light and scanning and transmission electron micrographs and correlated with physiological records obtained from the cochleae of these bats. [Work supported by USPHS, Grant NS 12445.]
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Time‐domain processing of target range information by central auditory neurons in the echolocating bat, Eptesicus fuscus (A)

A. S. Feng, J. A. Simmons, and S. A. Kick

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S85-S85 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Echolocating bats (Eptesicus fuscus) perceive either monaurally or binaurally the range of sonar targets with an acuity of about 1 cm, or a time delay acuity of about 60 μsec. Single‐unit recordings from cortical and midbrain auditory neurons in unanesthetized bats indicate response properties to stimuli consisting of pairs of simulated echolocation signals (three‐harmonic descending FM sweeps with energy from 23 to 100 kHz) with naturally occurring transmission‐echo time delays and intensity differences. While many neurons respond to both transmissions and echoes given sufficient intensities and long echo delays, some neurons respond exclusively to the pair when the time delay is within a narrow range. Their temporal response selectivity increases with decreasing overall absolute transmission‐echo intensity but is independent of intensity differences between transmissions and echoes. These results demonstrate “tuning” of central auditory neurons to specific echo delays, providing the neural basis for target range perception in bats and possibly perception of temporal structure of sounds in other animals. [Work supported by NSF and NIH.]
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A map of auditory space in the midbrain of the owl (A)

E. I. Knudsen and M. Konishi

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S85-S85 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Auditory units that responded to sound only when it originated from a limited area of space were found in the lateral and anterior portions of the midbrain auditory nucleus (nucleus mesencephalicus lateralis pars dorsalis, MLD) of the owl. The response properties of these units were studied in five barn owls (Tyto alba) using a remotely controlled, movable sound source under free‐field, anechoic conditions. The area of space to which such a unit responded was virtually independent of the nature (tone, click, or noise) and the intensity of the sound stimulus, and was defined as the unit's receptive field. Within a unit's receptive field could be found a small area to which the unit would respond with greatest vigor. This area of space was termed the unit's best area. Units in the lateral and anterior portions of MLD were systematically arranged according to the azimuth and elevation of their best areas. Units with contralateral best areas were located posterolaterally; units with ipsilateral best areas were located anteromedially. Elevation was arrayed along the dorsoventral axis with high best areas located dorsally and low best areas ventrally. [Work supported by NIH.]
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The acuity of phonotactic approach in the green treefrog Hyla cinerea (A)

J. Rheinlaender, R. R. Capranica, and H. C. Gerhardt

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S86-S86 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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The phonotactic responses of 41 individual females were videotaped to determine their head orientation prior to each leap and the direction and distance of the leaps in approaching the sound source broadcasting conspecific mating calls. Each approach consists of a sequence of zig‐zag hops which results in alternating stimulation of the right and left ears. This form of navigation is at times supplemented by scanning motions of the head. In 80% of all hops observed the deviation of the head and the subsequent jump from the sound axis falls within ±30°. At head angles less than ∼10° the subsequent jump is less well oriented than for greater angles. This means that a certain minimum of interaural difference is required for accurate sound localization. These behavioral results thus indicate the magnitude of binaural cues that must be processed by the treefrog's CNS. [Work supported by NIH and Heinrich‐Hertz‐Stiftung.]
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Representation of interaural time and intensity differences for clicks at the brachium of the inferior colliculus in the rat (A)

B. M. Clopton and M. S. Silverman

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S86-S86 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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A click presented at one ear evokes a synchronous discharge in the brachium of the inferior colliculus on the opposite side. We sampled this response in rats by recording gross potentials from the surface of the brachium and observed the effect of clicks delivered to the ipsilateral ear on the magnitude of the response. Strong binaural interaction was observed as interaural intensity differences (IID's) and interaural time differences (ITD's) were varied. This interaction for IID's agreed with that previously reported for data pooled from single‐unit observations, but the brachial potential technique allowed extensive IID and ITD combinations to be investigated in a single animal. Ipsilateral clicks that were more intense than contralateral clicks by 20 dB or more usually suppressed the contralateral response by at least 75%. Little ipsilateral suppression or even facilitation was observed for binaural clicks of equal intensity or with contralateral clicks more intense. ITD's of 200 μsec or less often had effects of similar magnitude, but the time effects' usually depended on IID's falling within the physiological range. Anesthetic effects were observed, and previous findings concerning the effects of developmental auditory deprivation and of selective lesioning of afferent pathways on binaural interactions in single neurons were confirmed.
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Phase interactions resulting from the avain interaural pathway (A)

J. J. Rosowski and J. C. Saunders

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S86-S86 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Acoustic measures of sound transmission across the effective interaural pathway (the interaural pathway and a tympanic membrane) have described a 20–30 dB attenuation of frequencies within the audible range of the chicken [J. J. Rosowski, J. Acoust. Soc. Am. 61, S3(A) (1977)]. The present report is concerned with the phase delay imposed by the effective interaural pathway. Cochlear microphonic responses were recorded in young chickens under conditions of homolateral or contralateral sound stimulation. The stimuli consisted of continuous pure tones with frequencies between 125 and 6300 Hz. The phase response of the CM relative to the phase of the stimulus at the directly stimulated tympanic membrane was determined. Comparison of the CM phase response between conditions of homolateral or contralateral stimulation yielded a measure of the effective phase delay resulting from the interaural pathway. The interaural change in phase (Δϕ) for frequencies between 125 and 500 Hz was 180°. This finding suggests that the interaural pathway allows a stimulation of the opposite tympanic membrane in the reverse direction of normal stimulation. At higher frequencies the interaural Δϕ increased such that a Δϕ of 800° was measured at 6300 Hz. These phase delays are much greater than would be expected from the interaural distances involved. Binaural stimulation resulted in complex interactions of the two stimuli which brought about changes in recorded CM amplitude and phase. A possible relationship between these interactions and localization phenomena will be discussed. [Work supported by NSF.]
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Auditory corticotectal connections of cat (A)

R. A. Andersen, R. Snyder, and M. M. Merzenich

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S86-S86 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Microelectrode recording techniques and the anterograde transport of tritiated amino acids (TAA) were utilized to demonstrate the projections of AI, AII, and the anterior auditory field (AAF) to the inferior colliculus (IC). Microinjections of TAA into AI resulted in two restricted, labeled laminae in the central IC of both sides: one in the dorsomedial division of the central nucleus (ICC) and one in the pericentral nucleus (ICP). The location and orientation of the projection arrays, as a function of the best frequencies of the cortical injection sites, were consistent with best frequency‐position data obtained in microelectrode mapping studies in the ICC. With injections in AII near the border of AI, very sparse, diffuse labeling in ICP and in the dorsal and medial aspect of IC was observed. No projection to IC was observed in four AAF cases. These results indicate that (1) of these three fields, AI has the greatest descending input to IC; (2) the projection from AI is topographic (cochleotopic); and (3) the projections to the dorsomedial division of ICC are laminar and the position and orientation of the the laminae are appropriate with their being continuous with the morphologically laminated ventral lateral division. [Supported by NIH grant NS‐10414.]
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Visual attention and tone‐burst evoked potentials (A)

B. W. Anderson and L. C. Oatman

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S86-S86 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Tone‐burst evoked potentials were used to examine the differential effects of visual attention on different frequencies. Unanesthetized cats, chronically implanted in the auditory cortex, cochlear nucleus, and round window, were trained to attend to a visual stimulus while irrelevant stimuli (85 dB SPL tone bursts) were continuously presented at a rate of 1/sec. Peak‐to‐peak amplitudes of evoked potentials from the auditory cortex and cochlear nucleus were significantly reduced during the attention period when compared to the pretest and post‐test control periods, but no significant changes were found at the round window (cochlear microphonic) for the same periods. The greatest suppression occurred in the middle frequencies (700–5000 Hz) although some suppression occurred across all frequencies. These data demonstrate that, during attention to a visual stimulus, auditory stimuli are attenuated maximally in the middle frequencies presumably via the olivocochlear bundle.
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Short‐latency evoked response correlations of psychophysical phenomena: Preliminary results from forward masking studies (A)

R. R. Stanny and L. F. Elfner

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S86-S87 (1977); (2 pages)

Online Publication Date: 11 Aug 2005

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Human wave V (8 msec latency) responses were recorded under forward masking conditions using vertex‐mastoid electrodes. Masking and masked stimuli were either noise‐burst clicks or sinusoids. When pairs of 1 msec clicks are presented monaurally at 75 dB SPL, the masked‐stimulus wave V response is reduced by about 93% when the interstimulus interval is 1 msec. Amplitude recovery is rapid and largely complete by 10 msec. 4 msec sinusoids presented singly at constant 55 dB sensation levels produce a bandpass frequency response function with a peak at about 3 kHz. When frequency is reduced below about 9 kHz, the wave V complex separates into two components: A fast positive defection with a stable latency of about 8 msec and a slower biphasic response with a latency inversely related to frequency (the later portion of this wave appears to overlap the postauricular muscle response). Forward masking of these responses is restricted to the spectral region of the masking sine wave; work directed toward determining the shape of the wave V “filter” is currently under way.
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Study of a combined noninvasive‐ECochG and BSER recording technique (A)

J. D. Durrant

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S87-S87 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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A new electrode was developed for recording the electrocochleogram (ECochG) from the ear canal. The electrode has a self‐retaining assembly, is placed without the aid of an otoscope, requires no anesthesia, and can be used under an earphone. The electrode, per se, is of the surface type and is placed on the floor of the ear canal about ½‐cm from the eardrum. The focus of this report is on observations carried out in normal hearing subjects in which the ear canal recording was referenced to an electrode located on the forehead at hairline (which for purposes of recording the brainstem responses is not much different from the vertex). The interest in this configuration was in examining the potential for, in effect, combining the ECochG and the BSER (brainstem evoked response) in a single recording. This technique has been found to provide fairly reliable brainstem responses, however, with an appreciable facilitation of the eighth nerve response (N1 or wave I). Unfortunately, the latter has proven to be quite variable, independent of the overall sensitivity of the recording. Possible sources of this problem and the relative limitations versus merits of this recording technique are discussed.
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Effects of stimulus frequency on adaptation in auditory nerve fibers (A)

Paul J. Abbas

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S87-S87 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Several experimental methods of depressing the response of auditory nerve fibers to tonal stimuli (such as two‐tone suppression or stimulation of the efferent bundle) has been shown to reduce the response to signal frequencies at or near fiber CF more than to frequencies greater or less than CF. In this study we have used an adapting tone presented before each test tone burst to reduce the fiber's response. We then observed the effects of changing test‐tone frequency. Discharge rate in response to the test tone was measured as a function of stimulus level with and without the adapting tone present. The adapting tone was always at fiber CF and held at a fixed level. The difference in discharge rate between presentation with and without the adapting tone was then plotted as a function of stimulus level. This difference was approximately constant over a range of stimulus levels [as reported by R. L. Smith, J. Acoust. Soc. Am. 59, S16(A) (1975)]. The depression in discharge rate was found to be approximately constant across a wide range of stimulus frequencies both above and below fiber CF.
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Physiological masking functions in normal and acoustically traumatized cats (A)

N. T. Shepard and P. J. Abbas

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S87-S87 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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In cats that have undergone acoustic traumatization, it has been observed that several characteristics in the shape of single auditory nerve fiber tuning curves correspond to histological changes in the hair cells of the cochlea [N. Y. S. Kiang, M. C. Liberman, and R. A. Levine, Ann. Otol. Rhinol. Laryngol. 85, 752–768 (1976)]. Dallos and Cheatham (J. Acoust. Soc. Am. 59, 591–597 (1976)] using the whole‐nerve action potential as a response have demonstrated masking curves in normal animals similar in shape to single‐fiber tuning curves. We have measured whole‐nerve action potential tuning curves (AP tuning curve) in both normal and acoustically traumatized cats to investigate the sensitivity of such a measure in reflecting changes in single‐fiber tuning curves. A tonal masker in a forward‐masking paradigm was used to elicit the measured responses. AP tuning curves were generated at several signal frequencies in order to measure the physiological changes at different places along the cochlea. A preliminary review of the data indicate that the AP tuning curves in acoustically traumatized animals can show a broadening of the tip region relative to normals.
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Frequency adaptation in the cochlear nerve of chinchilla (A)

S. M. Hou

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S87-S87 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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The behavior of cochlear nerve responding to high‐frequency click‐train stimuli was studied by signal averaging technique from chinchilla. The findings support earlier human psychophysical observations, i.e., the adaptation rate of the cochlear nerve is faster at higher stimulus frequencies than at lower ones (⩾2000 Hz). It is also demonstrated that within a long stimulus train (200 ms or longer}, the cochlear nerve exhibits a cyclic neural recovery pattern. The period of this cyclic event is also a function of stimulus frequency. These evidences concur with the current concept of auditory fatigue, however, the magnitudes of adaptation of brain stem evoked component was found to be less sensitive than that from cochlear nerve in the intrastimulus recovery cycle. [Supported in part by an NIH grant and grants to Dr. David M. Lipscomb.]
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Auditory temporal modulation transfer function for the goldfish (A)

R. R. Fay

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S88-S88 (1977); (1 page) | Cited 1 time

Online Publication Date: 11 Aug 2005

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Restrained goldfish were classically conditioned to suppress respiration to an acoustic signal consisting of a seven second period of sinusoidal amplitude modulation impressed upon a continuous wide‐band noise. Psychometric functions were constructed by plotting a measure of respiratory suppression as a function of the signal's modulation depth (m). Arbitrarily defined threshold values of m were plotted as a function of modulation frequency between 5 and 600 Hz. This TMTF is essentially flat to about 250 Hz with values of 20 log m falling between −12 and −18. The intensity difference limen is calculated to be about 1 dB(ΔI/I approximately 0.25), and the minimum integration time, although not precisely measured, appears to be less than that for man. This conclusion is consistent with the finding that goldfish show considerably less temporal summation in signal detection than man [A. Popper, J. Acoust. Soc. Am. 52, 596–602 (1972)]. The results suggest that the goldfish auditory system is specially adapted for detecting transient sounds, and for accurately preserving the fine structure (phase information) of auditory signals. [Research supported by the NSF.]
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Auditory sensitivity in the rabbit determined by a conditional nictitating of membrane response (A)

G. K. Martin, B. L. Lonsbury‐Martin, and J. Kimm

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S88-S88 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Auditory sensitivity was measured in New Zealand white rabbits trained by means of a behavioral technique utilizing classical conditioning of the nictitating membrane (NM) response. Conditioning trials consisted of the presentation of a 350 msec pure tone stimulus of which the final 100 msec overlapped with the occurrence of a shock to the posterior orbital region. A conditioned NM response was defined as a 0.5 mm deflection with a latency ranging from 130 to 260 msec following tone onset. Threshold and latency‐intensity functions were collected from 500 Hz to 32 kHz using the method of constant stimuli under closed field conditions. Animals were most sensitive to test stimuli between 8 and 16 kHz with maximum sensitivities at sound pressure levels ranging from −1 to 11 dB SPL. For frequencies above 16 kHz and below 3 kHz, sensitivity rapidly decreased. The latency of the NM response was found to be an inverse function of stimulus intensity over a fairly large dynamic range similar to the latency‐intensity functions obtained with operant reaction‐time tasks. A number of features will be discussed that make the rabbit NM preparation a highly desirable behavioral and/or neurophysiological model for studying auditory phenomena.
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Frequency selectivity in the parakeet: The relation between critical band and psychophysical tuning curves (A)

J. C. Saunders and G. R. Bock

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S88-S88 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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The critical band may be viewed as an indication of the bandwidth of the internal auditory filter. The bandwidth of a filter, as a measure of its frequency selectivity is not easily compared with the bandwidths of other filters. One useful measure of frequency selectivity, however, can be found by dividing the bandwidth of a filter at some arbitrary point below the peak, into the center frequency of the filter. This so called “Q” measure is valuable because it represents a ratio and thus can be compared among filters of different center frequencies. We have assumed that indirect measures of the critical band (the critical ratio) represent the bandwidth of the internal filter at a consistent point below the peak. We have thus calculated a Qcritical ratio for all the available data points in the parakeet. Psychophysical tuning curves (PTC) have been empirically obtained for eight different probe frequencies in the parakeet. A Q10 dB was calculated for each of these tuning curves and compared with the data describing Qcritical ratio, at ten different frequencies. The plot over frequency of Qcritical ratio and Q10 dB of the PTC's, although differing in absolute values, were nearly identical in shape. Frequency selectivity is poor in the low frequencies, raises sharply between 2.5 and 4.0 kHz, and then becomes poor again at higher frequencies. The results will be discussed with regard to the relation between the critical band and psychophysical tuning curves and frequency selectivity in the parakeet. [Work supported by NSF.]
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Environmental features governing signal design in bat sonar (A)

J. A. Simmons

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S88-S88 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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Echolocating bats (800 species) represent a wide range of types of practical sonar systems evolved to fit specific acoustic environments and varying target situations. Bats which pursue isolated targets use narrow‐band, CF signals for searching and low‐distortion, moderately broadband FM signals for target characterization. Bats pursuing prey in the general vicinity of obstacles use two‐ or three‐harmonic broadband FM‐plus‐CF signals to detect and characterize targets. These bats always have an ear out for potential flight hazards. Some bats operating in dense clutter use multiple‐harmonic, very broadband FM signals for target detection and characterization. Other bats use narrow‐band, long‐CF signals for Doppler resolution of targets in clutter and moderately broadband FM signals for target description. Some species are adaptable and can use several of these signal patterns. Elements of sonar signal design are illustrated with real‐world weights attached to their significance in data on bat echolocation. In particular, attention is focused on use of multiple‐harmonic waveforms in clutter and the coupling of different signals into compound transmissions for processing by compound receivers.
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Temperature coupling in the vocal communication system of the treefrog, Hyla versicolor (A)

H. Carl Gerhardt

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S88-S89 (1977); (2 pages)

Online Publication Date: 11 Aug 2005

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The pulse‐repetition rate (PR) of mating calls of male treefrogs is highly temperature dependent. Since females are attracted by mating calls over a range of at least 9°C, the question arises: Do vocalizations produced at different temperatures attract females equally well? Gravid females were given a choice between two synthetic calls with PR's typical of those produced by males at about 16°C (15/sec) and 24°C (24/sec), respectively. Eight females chose the call with a PR of 24/sec when their body temperatures were about 24°C; subsequently, six of the same females responded when their body temperatures were about 16°C; they chose the call with a PR of 15/sec. Four females initially tested at 16°C chose the 15/sec call; subsequently at 24°C, two chose the 24/sec call and one chose the 15/sec call. These results were obtained at a playback level of 75 dB SPL re 2 × 10−4 μ bar; at 85 dB, females chose the 15/sec call at 16°C but failed to discriminate at 24°C. Evolutionary and neurophysiological implications will be discussed. [Supported by NSF and NIH.]
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Some unexplained properties of bird song (A)

Joseph C. Beaver

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S89-S89 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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The standard theory of avian “song” production of Greenewalt [Bird Song: Acoustics and Physiology, Washington, D.C.(1968)] claims a generation by the syringeal internal tympaniform membrane, vibrating at a “carrier frequency,” with amplitude modulation supplied by secondary vibration of the external labium. Whether these are driving or driven members is currently under investigation. However, several interesting questions remain either unaddressed or unresolved. Vertical spectrographic lines appear at the onset of “voicing” for some species comparable to those for unvoiced stops in human speech; “trills” (8–25 per sec) too slow for “amplitude modulation” are found in others. What are the articulatory correlates for these phenomena? Again, Greenewalt has argued that for species which generate a harmonic series (he admits even most passerines can and do), the harmonic emphasized varies in ratio to how much the bird descends below a “frequency threshold” where the Fourier transform is actuated, but Sutherland and McChesney [“Sound production in two species of geese,” Living Bird 4, (1965)] have demonstrated that the harmonic emphasized by the blue and snow goose depends on tracheal length. Tracheal length for many species is such that it could reinforce source‐generated harmonics. Possible articulatory correlates for the first two phenomena are discussed, and for the third problem spectrographic evidence is presented to support a theory that a frequency capable of tracheal reinforcement serves as a “target,” or “home” frequency for many species.
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Sound production of humpback whales, Megaptera novaeangliae, in Alaskan waters (A)

P. O. Thompson, W. C. Cummings, and S. J. Kennison

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S89-S89 (1977); (1 page) | Cited 1 time

Online Publication Date: 11 Aug 2005

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Underwater sounds of feeding humpback whales were recorded 90–130 km south of Juneau in August, 1975. Although there were scattered grunts, yelps, moans, and low‐frequency narrow‐band pulses, as expected, the most pervasive sounds were trains of 25–80 Hz broadband pulses that had a mean repetition rate of 1 per sec. They were superposed on 40ndash;1250‐Hz continuous noise which swelled and decayed as pulse trains began and ended, varying in duration from 15 to 100 sec. Incidental sounds made by surfaced animals were shrieks and trumpeting made through the blowholes and wide‐band pulses produced by flipper or tail slaps on the water's surface. Also recorded were weaker wide‐band pulse trains that were characterized by (1) Lack of energy below 500 Hz, (2) uneven amplitude and repetition interval, and (3) repetition rate of several per sec. The source of these pulses was believed to be clashing of baleen plates from wave action as a whale skimmed food organisms at the surface. Estimated maximum underwater source levels (referred to 1 μ Pa at 1 m) were grunt, 190 dB; trumpeting, 185 dB; tail slap, 183 dB; shriek, 180 dB; and low‐frequency broadband pulse, 176 dB.
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Improving the acoustic properties of a dolphin tank (A)

Lynn B. Poché, Jr., Peter H. Rogers, and William V. Carlson

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S89-S89 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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In many cases, dolphin tanks, like auditoriums, are designed with no special effort directed toward achieving acoustical perfection. Our measurements were to be made in a small pen in a large semicircular tank which was divided much the same as a railroad roundhouse, and contained seals and sea lions as well as dolphins. The walls were smooth concrete. Our object was to measure dolphin echolocation signals, and both reverberation and isolation presented serious problems. A wood lining which is echo suppressing in the frequency range of 10–150 kHz was developed and installed. The lining was constructed in 6‐ft square curtain panels, which were made up from small (3.5 × 7 × 2.5‐in.) blocks. This built‐up construction was necessitated by the particular grain orientation and pressure treatment of the wood required. The development of a satisfactory surface configuration and grain orientation was carried out in a small laboratory tank using 12‐in. square panels. Echo‐reduction measurements made in the USRD Lake Facility on full‐size panels and in the dolphin tank on the completed lining are in good agreement with the small‐tank data and show about 15–30 dB echo reduction over the entire frequency range. Transmission loss increases from about 15 dB at 10 kHz to 40 dB at the high frequencies.
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Prenatal sound transmission and exceptional antennae (A)

Henry M. Truby

J. Acoust. Soc. Am. Volume 62, Issue S1, pp. S89-S89 (1977); (1 page)

Online Publication Date: 11 Aug 2005

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In the antedating of infantile speech‐and‐hearing acquisition, largely on the basis of cryprint and auditory response criteria, investigation of the neonatal period soon indicated the antecedental significance of the prenatal period [H. M. Truby, “Prenatal speech: A speculation,” CRI SR 2567 (1967)]. Observations of some years re early antenatal hearing in the developing human prenate (fetus) [B. Johansson, E. Wedenberg, and B. Westin, “Measurement of tone response by the human fetus,” Acta Otolaryngolica 57, 188 (1964)] corresponded with observable vocalization maturation in prematurely delivered infants (premies) of the 900‐g‐and‐under class [H. Truby, J. Lind, and J. Bosma, “Cry sounds of the newborn infant (1960),” Acta Pædiatrica 163, 51 (1965)]. In exploration via contact microphony of the transmission properties of the amniotic sac, from midpregnancy on, the unique mother‐prenate juxtaposition (Merriam‐Webster IlI, p. 1229) is demonstrated to be eminently suitable for direct biophysiological sound transmission to the alert unborn baby of maternal speech, singing, humming, etc. —as well as shouting, screaming, crying, etc. — consequently placing said prenate in, for example, optimal oral‐aural relationship for speech imprinting [H. Truby, “Prenatal and neonatal speech…” in Child Language — 1975, 57–101 (1976)]. Auscultation and stethoscopic recording at the external abdominal wall of the pregnant mother during speech, reveal a high order of intelligible speechsound transmission available in utero to the developing prenate. Serendipitously, the amniotic sac is revealed as an exceptional antenna for transmitting extracorporeally generated, conventional sound phenomena. Thus, in summation: The extended amniotic sac in vivo is an exceptional antenatal hearing medium, speechsound processor, and bioacoustic antenna and transmitter. [Author support: Pediatrics Department, Mt. Sinai Medical Center, Miami Beach, FL.]
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