Contextual effects on loudness judgments for sounds with continuous changes of intensity are reflected in nonauditory areas

Auditory perceptual discomfort and low-hearing tolerance in the first episode psychosis

Awareness of perceptual and sensory changes that might occur in visual, auditory, proprioception, and other senses, in the early stages towards the First Episode Psychosis (FEP), and their subsequent sensorial evolution as the disturb progresses deeper into an acute episode, might be a key element for interrupting the process. In the present study, we investigated hearing discomfort/tolerance to 16 given sound streams. Sixteen people diagnosed with FEP, participated in the experiment. Sixteen frequency sweeps varying in modulation envelopes (sawtooth, sine), order (ascending, descending), duration (4s, 8s), and range (50–8000 Hz, 2–8 kHz) were presented randomly, but always in the same sequence, to FEP and healthy controls (HC). The level of discomfort was estimated by the participant by making a mark across a continuous line whose extremes read “nothing bad” (left) and “too bad” (right). Results showed that ascending sine pure frequency sweeps (p < 0.01) and descending sine pure frequencies sweeps (p < 0.01) caused the maximum discomfort in FEP. Other variables also showed differences between FEP and HC, and FEP were always more intolerant to such pure frequency sweeps than HC. We conclude that this might be useful for very early assessment of people at risk, people with FEP, and people with schizophrenia.

Contextual effects on loudness judgments for sounds with continuous changes of intensity are reflected in nonauditory areas

Psychoacoustic research suggests that judgments of perceived loudness change differ significantly between sounds with continuous increases and decreases of acoustic intensity, often referred to as “up‐ramps” and “down‐ramps.” The magnitude and direction of this difference, in turn, appears to depend on focused attention and the specific task performed by the listeners. This has led to the suspicion that cognitive processes play an important role in the development of the observed context effects. The present study addressed this issue by exploring neural correlates of context‐dependent loudness judgments. Normal hearing listeners continuously judged the loudness of complex‐tone sequences which slowly changed in level over time while auditory fMRI was performed. Regression models that included information either about presented sound levels or about individual loudness judgments were used to predict activation throughout the brain. Our psychoacoustical data confirmed robust effects of the direction of intensity change on loudness judgments. Specifically, stimuli were judged softer when following a down‐ramp, and louder in the context of an up‐ramp. Levels and loudness estimates significantly predicted activation in several brain areas, including auditory cortex. However, only activation in nonauditory regions was more accurately predicted by context‐dependent loudness estimates as compared with sound levels, particularly in the orbitofrontal cortex and medial temporal areas. These findings support the idea that cognitive aspects contribute to the generation of context effects with respect to continuous loudness judgments.