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Recent bioacoustic articles in J. Comp. Physiol. A.

Subject: Recent bioacoustic articles in J. Comp. Physiol. A.
From: "Sonja Amoser" <>
Date: Fri, 6 Mar 2009 21:48:12 +0100
Volume 195(1):

Joshua A. Deily and Johannes Schul (2009): Selective phonotaxis in 
Neoconocephalus nebrascensis (Orthoptera: Tettigoniidae): call recognition at 
two temporal scales. J. Comp. Physiol. A 195(1), 31-37.

Abstract: The calls of many Orthopteran species are comprised of a simple trill 
of pulses, the temporal pattern of which is important for call recognition. 
Male Neoconocephalus nebrascensis produce pulses with a temporal structure 
typical for the genus. However, they modify this pattern by grouping their 
pulses into verses, thereby creating a higher order temporal structure. The 
importance of the pulse pattern and verse structure for call recognition in N. 
nebrascensis was determined using a walking compensator. Females required the 
conspecific pulse pattern for call recognition, responding only when the 
intervals between pulses were short or absent. Females also required the verse 
structure for call recognition, and recognized the verse structure only when 
the amplitude modulation depth between verses and pauses exceeded 18 dB. We 
discuss that the verse recognition mechanism is a derived trait adapted for 
pre-mating isolation. We hypothesize that the unusually large amplitude 
modulation required for verse recognition forces males to synchronize their 
calls in order to preserve an attractive pattern. Call synchrony appears to be 
the outcome of cooperation, rather than competition, in this species.

For reprints please contact Johannes Schul (Email: 

Mariana L. MelcÃn, Hans-Ulrich Schnitzler and Annette Denzinger (2009): 
Variability of the approach phase of landing echolocating Greater Mouse-eared 
bats. J. Comp. Physiol. A 195(1), 69-77.

Abstract: The approach phase of landing vespertilionid bats ends with a group 
of calls, which either consists of buzz I alone or buzz I and buzz II. To 
understand the possible role of buzz II, we trained Myotis myotis to land on a 
vertical grid, and compared the flight and echolocation behavior during 
approach in trials with and without buzz II. During the approach, we did not 
find any differences in the echolocation behavior until the end of buzz I which 
indicated whether buzz II was emitted or not. However, bats flying from the 
periphery of the flight channel, such that they had to make a small turn at the 
very last moment, finished the sequence with a buzz II. Bats flying on a rather 
stereotyped trajectory near the center of the flight channel without last 
instant corrections emitted buzz I alone. Our results indicate that buzz II 
occurred only on trajectories that implied a higher risk to fail at landing. 
The information delivered by buzz II reaches the bat too late to be used for 
landing. Therefore, we hypothesize that buzz II may help the bats to evaluate 
unsuccessful attempts and to eventually react adequately.

For reprints please contact Mariana L. MelcÃn (Email: 

Sarah A. Stamper, Mary E. Bates, Douglas Benedicto and James A. Simmons (2009): 
Role of broadcast harmonics in echo delay perception by big brown bats. J. 
Comp. Physiol. A 195(1), 79-89.

Abstract: Big brown bats (Eptesicus fuscus) emit frequency-modulated (FM) 
echolocation sounds containing two principal down-sweeping harmonics (FM1 ~ 
55â25 kHz, FM2 ~ 105â50 kHz). To determine whether each harmonic contributes to 
perception of echo delay, bats were trained to discriminate between 
âsplit-harmonicâ echoes that differed in delay. The batâs broadcasts were 
picked up with microphones, and FM1 and FM2 were separated with highpass and 
lowpass filters at about 55 kHz, where they overlap in frequency. Both 
harmonics then were delivered from loudspeakers as positive stimuli in a 
2-choice delay discrimination procedure with FM1 delayed 3.16 ms and FM2 
delayed 3.46 ms (300 Îs delay split). Negative stimuli contained FM1 and FM2 
with the same filtering but no delay separation. These were presented at 
different overall delays from 11 down to 3 ms to measure the batâs delay 
discrimination acuity for each harmonic in the split harmonic echoes. The bats 
determined the delays of both FM1 and FM2, but performance was overlaid by a 
broad pedestal of poor performance that extended for 800 Îs. Splitting the 
harmonics by 300 Îs appears to defocus the batâs representation of delay, 
revealing the existence of a process for recognizing the normally simultaneous 
occurrence of the harmonics.

For reprints please contact Sarah A. Stamper (Email: 

Volume 195(2):

Tobias Riede and Roderick A. Suthers (2009): Vocal tract motor patterns and 
resonance during constant frequency song: the white-throated sparrow. J. Comp. 
Physiol. A 195(2), 183-192.

Abstract: Bird song is a complex behavior that requires the coordination of 
several motor systems. Sound is produced in the syrinx and then modified by the 
upper vocal tract. Movements of the hyoid skeleton have been shown in the 
northern cardinal (Cardinalis cardinalis) to be extensively involved in forming 
an oropharyngealâesophageal cavity (OEC), which contributes a major resonance 
to the vocal tract transfer function. Here we report that a similar 
relationship exists between the volume of the OEC and the fundamental frequency 
in the white-throated sparrow (Zonotrichia albicollis) whose song, unlike that 
of the cardinal, consists of a series of almost constant frequency notes. 
Cineradiography of singing sparrows shows that the oropharyngeal cavity and 
cranial end of the esophagus expand abruptly at the start of each note and 
maintain a relatively constant volume until the end of the note. Computation of 
the vocal tract transfer function suggests a major resonance of the OEC follows 
the fundamental frequency, making sound transmission more efficient. The 
presence of similar prominent song-related vocal tract motor patterns in two 
Oscine families suggests that the active control of the vocal tract resonance 
by varying the volume of the OEC may be widespread in songbirds.

For reprints please contact Tobias Riede (Email: 

Amanda M. Lauer, Robert J. Dooling and Marjorie R. Leek (2009): Psychophysical 
evidence of damaged active processing mechanisms in Belgian Waterslager 
Canaries. J. Comp. Physiol. A 195(2), 193-202.

Abstract: Belgian Waterslager canaries (BWC), bred for a distinct low-pitched 
song, have an inherited high-frequency hearing loss associated with hair cell 
abnormalities. Hair cells near the abneural edge of the papilla, which receive 
primarily efferent innervation in normal birds, are among the most severely 
affected. These cells are thought to support nonlinear active processing in the 
avian ear, though the mechanisms are poorly understood. Here we present 
psychophysical evidence that suggests degraded active processing in BWC 
compared to normal-hearing non-BWC. Critical ratios, psychophysical masking 
patterns and phase effects on masking by harmonic complexes were measured in 
BWC and non-BWC using operant conditioning procedures. Critical ratios were 
much larger in BWC than in non-BWC at high frequencies. Psychophysical tuning 
curves derived from the masking patterns for BWC were broadened at high 
frequencies. BWC also showed severely reduced phase effects on masking by 
harmonic complexes compared to non-BWC. As has been hypothesized previously for 
hearing-impaired humans, these results are consistent with a loss of active 
processing mechanisms in BWC.

For reprints please contact Amanda M. Lauer (Email: 

Kind regards


Dr. Sonja Amoser
SteinrieglstraÃe 286
3400 Weidlingbach

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