Acoustic Hearing Can Interfere With Single-Sided Deafness Cochlear-Implant Speech Perception.

Objectives: Cochlear implants (CIs) restore some spatial advantages for speech understanding in noise to individuals with single-sided deafness (SSD). In addition to a head-shadow advantage when the CI ear has a better signal-to-noise ratio, a CI can also provide a binaural advantage in certain situations, facilitating the perceptual separation of spatially separated concurrent voices. While some bilateral-CI listeners show a similar binaural advantage, bilateral-CI listeners with relatively large asymmetries in monaural speech understanding can instead experience contralateral speech interference.

The fluctuating masker benefit for normal-hearing and hearing-impaired listeners with equal audibility at a fixed signal-to-noise ratio.

Normal-hearing (NH) listeners can extract and integrate speech fragments from momentary dips in the level of a fluctuating masker, yielding a fluctuating-masker benefit (FMB) for speech understanding relative to a stationary-noise masker. Hearing-impaired (HI) listeners generally show less FMB, suggesting a dip-listening deficit attributable to suprathreshold spectral or temporal distortion. However, reduced FMB might instead result from different test signal-to-noise ratios (SNRs), reduced absolute audibility of otherwise unmasked speech segments, or age differences.

Role of intracranial cavities in avian directional hearing.

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 variations in the intracranial air pressure. In awake birds, the middle ears and connected cavities are vented actively through the pharyngotympanic tube.

Lingual articulation in songbirds.

Lingual articulation in humans is one of the primary means of vocal tract resonance filtering that produces the characteristic vowel formants of speech. In songbirds, the function of the tongue in song has not been thoroughly examined, although recent research has identified the oropharyngeal-esophageal cavity as a resonance filter that is actively tuned to the frequency of the song. In northern cardinals (Cardinalis cardinalis), the volume of this cavity is inversely proportional to the frequency of the song above 2 kHz.

Light-dependent orientation responses in animals can be explained by a model of compass cue integration.

The magnetic compass sense of animals is currently thought to be based on light-dependent processes like the proposed radical pair mechanism. In accordance, many animals show orientation responses that depend on light. However, the orientation responses depend on the wavelength and irradiance of monochromatic light in rather complex ways that cannot be explained directly by the radical pair mechanism.

Measurements and predictions of hooded crow (Corvus corone cornix) call propagation over open field habitats.

In a study of hooded crow communication over open fields an excellent correspondence is found between the attenuation spectra predicted by a "turbulence-modified ground effect plus atmospheric absorption" model, and crow call attenuation data. Sound propagation predictions and background noise measurements are used to predict an optimal frequency range for communication ("sound communication window") from an average of crow call spectra predicted for every possible combination of the sender/receiver separations 300, 600, 900, and 1200 m and heights 3,6,9 m thereby creating a matrix assumed relevant to crow interterritorial communication. These predictions indicate an optimal frequency range for sound communication between 500 Hz and 2 kHz.

Comodulation detection differences in the hooded crow (Corvus corone cornix), with direct comparison to human subjects.

Envelope modulations have been shown important in determining the effectiveness of masking noises. For example, the threshold for detecting a signal flanked by maskers is lower if the maskers and the signal are modulated with different envelopes, rather than the same envelope (comodulation). This threshold change is called the comodulation detection difference (CDD).