Adaptive auditory brightness perception

Perception adapts to the properties of prior stimulation, as illustrated by phenomena such as visual color constancy or speech context effects. In the auditory domain, only little is known about adaptive processes when it comes to the attribute of auditory brightness. Here, we report an experiment that tests whether listeners adapt to spectral colorations imposed on naturalistic music and speech excerpts. Our results indicate consistent contrastive adaptation of auditory brightness judgments on a trial-by-trial basis. The pattern of results suggests that these effects tend to grow with an increase in the duration of the adaptor context but level off after around 8 trials of 2 s duration. A simple model of the response criterion yields a correlation of r = .97 with the measured data and corroborates the notion that brightness perception adapts on timescales that fall in the range of auditory short-term memory. Effects turn out to be similar for spectral filtering based on linear spectral filter slopes and filtering based on a measured transfer function from a commercially available hearing device. Overall, our findings demonstrate the adaptivity of auditory brightness perception under realistic acoustical conditions.

Wavelength-Switchable Dissipative Soliton Fiber Laser With a Chirped Fiber Grating Stop-Band Filter

We report a wavelength-switchable single-polarization dissipative soliton (DS) mode-locked fiber laser using a chirped fiber Bragg grating (FBG) for spectral filtering. The chirped FBG, when inserted into the ring cavity, provides a stopband from 1045 nm to 1057 nm, which is used for spectral filtering in this all-normal-dispersion mode-locked Yb-doped fiber laser. The combination of the chirped FBG and the Yb gain profile help the formation of the DS. The laser delivers wavelength-switchable and polarized (28 dB) DS of 6.1 nJ and 29 ps at 1032 nm, and 4.3 nJ and 24 ps at 1068 nm, respectively. To the best of our knowledge, this is the direct proof that a bandpass filter is not indispensible to achieve stable DS in ps fiber lasers.