The utility of brief, spectrally rich, dynamic sounds in the passive oddball paradigm

Experiments investigating auditory processing often utilize spectrally rich, dynamic stimuli to simulate an ecologically valid auditory environment in the laboratory. Often, however, these stimuli do not allow for a strict control of the timing of auditory sensory information which may be distributed over the whole duration of a given sound. In the present study, brief (20 ms long), dynamic, spectrally rich sounds were presented in the context of a passive oddball paradigm to young adults. The short duration made certain that the sensory information was delivered entirely within a 20 ms interval. Two sounds were presented as standards (45-45% probability), other two as deviants (5-5% probability) in random sequences, with a stimulus onset asynchrony (SOA) of 1500 ms. Deviants elicited the mismatch negativity and late difference negativity (LDN) event-related potential components. No N1-effect was produced by deviants, which suggests that the acoustic energy is spread over many different features due to the dynamic spectral properties, which, combined with the brief duration, causes insignificant refractoriness-effects at the present SOA. These results support the usefulness of brief natural sounds in auditory research. The elicitation of LDN in an adult group was an unexpected finding, because LDN is mostly found in children, but not in adults. This result might indicate that LDN elicitation depends on stimulation complexity: stimulus settings in which an LDN is registered in children but not in adults may be perceived as more complex by children than by adults.