Ole Næsbye Larsen

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1. The small (anterior) tympanal membrane in the ear of the cricketGryllus campestris L. is non-functional in hearing (Fig. 4). 2. The large (posterior) tympanum vibrates in its basic mode in the entire frequency range investigated (1–30 kHz). 3. The velocity and the phase angle (sound pressure to vibration velocity) of the large tympanum are very much(More)
The physical mechanisms of sound generation in the vocal organ, the syrinx, of songbirds have been investigated mostly with indirect methods. Recent direct endoscopic observation identified vibrations of the labia as the principal sound source. This model suggests sound generation in a pulse-tone mechanism similar to human phonation with the labia forming a(More)
Temporal coding in the moth ear was inferred from the response of the auditory receptor to acoustic stimuli with different temporal characteristics. 1. Determinations of the threshold with different stimulus pulse durations showed that the moth ear behaves as an energy detector with a maximum time constant (the integration time) of 25 ms. Pulse durations(More)
As animals vocalize, their vocal organ transforms motor commands into vocalizations for social communication. In birds, the physical mechanisms by which vocalizations are produced and controlled remain unresolved because of the extreme difficulty in obtaining in vivo measurements. Here, we introduce an ex vivo preparation of the avian vocal organ that(More)
In many birds, the middle ears are connected through an air-filled interaural pathway. Sound transmission through this pathway may improve directional hearing. However, attempts to demonstrate such a mechanism have produced conflicting results. One reason is that some species of birds develop a lower static air pressure in the middle ears when(More)
Previous studies of hair cell regeneration and hearing recovery in birds after acoustic overstimulation have involved relatively few species. Studies of the effects of acoustic overexposure typically report high variability. Though it is impossible to tell, the data so far also suggest there may be considerable species differences in the degree of damage(More)
The detection of signals in noise is important for understanding both the mechanisms of hearing and how the auditory system functions under more natural conditions. In humans, the auditory system gains some improvement if the signal and noise are separated in space (binaural masking release). Birds with small heads are at a disadvantage in separating noise(More)
Songbirds vocalizing in helium show a change in the spectral quality of their vocalizations. This effect is due to an increase in the speed of sound in helium that in turn alters the resonance properties of the vocal tract. Here, this approach is extended to a psittacine, the budgerigar (Melopsittacus undulatus), whose syringeal anatomy and innervation(More)
Ikaite, calcium carbonate hexahydrate, has by means of X-ray diffraction analyses of frozen samples been identified as the mineral component of the white spots formed in the shell of frozen shrimp during storage. When the shrimp thaw and the shell material is dried and kept at room temperature, ikaite rapidly transforms into a mixture of anhydrous calcium(More)
Whereas it is clear from anatomical studies that all birds have complex interaural canals connecting their middle ears, the effect of interaural coupling on directional hearing has been disputed. A reason for conflicting results in earlier studies may have been that the function of the tympanic ear and hence of the interaural coupling is sensitive to(More)