On the cognitive neurodynamics of listening effort: a phase clustering analysis of large-scale neural correlates

Simulations of hearing loss and hearing aid: effects on electrophysiological correlates of listening effort

In the last decades, many investigations were done to examine the effects of sensorineural hearing loss on the speech perception ability. Besides testing hearing impaired persons, there is also the possibility to simulate the hearing loss. Therefore, some electrophysiological as well as speech recognition studies were performed in normal hearing subjects using techniques to model the sensorineural hearing loss. Thus, the effects of peripheral hearing loss without central auditory pathologies can be examined. In previous studies, we have shown, that the wavelet phase synchronization stability (WPSS) of auditory late responses could serve as a possible indicator of listening effort. Now, the aims of this present study were to explore the effects on the WPSS by using two different simulations of hearing loss and a simulated hearing aid. The preliminary results showed, that in case of a simultaneous simulation of hearing loss by noise masking and a hearing aid, an objective discrimination between an easy and a difficult listening situation can be achieved. Furthermore, the WPSS reflected also a good discrimination by using the filtered and attenuated paradigms.

The effects of age and hearing impairment on the extraction of listening effort correlates

In clinical practice, an objective method to assess listening effort is still not available. The benefit of such a measure would be to reduce the listening effort in hearing impaired persons by an adequate adaption of their personal hearing aids. In foregoing studies, we have shown that the wavelet phase synchronization stability (WPSS) of auditory late responses (ALRs) could serve as a feasible measure of listening effort. Here, tonal and noise embedded syllabic paradigms were employed to achieve ALR sequences in normal hearing subjects. The aims of this ongoing study were 1) to extract the WPSS of ALR sequences in hearing impaired persons, middle-aged normal hearing persons and younger normal hearing subjects, 2) to investigate possible age-related influences on the WPSS and 3) to examine a feasible influence of the hearing loss on the WPSS. It is concluded, that the WPSS of ALR sequences can be extracted in normal hearing as well as in hearing impaired persons. An age related effect regarding the WPSS was not noticeable and the intergroup comparison of the difference of the WPSS showed a tendency to be larger for the hearing impaired compared to the normal hearing middle-aged subjects. The latest can be interpreted that this subject group showed a larger effort to solve the auditory paradigms.

Non-listening effort related parameters in auditory discrimination paradigms

Objective methods to asses listening effort are still missing in clinical settings. Thus, the focus of our ongoing research is the extraction of possible substrates of listening effort. This paper focuses on the non-effort related factor reaction time (RT) on the different components of auditory late responses (ALRs). It makes sense to consider this factor in the context of age related changes of the RT. For the comparison of the ALR components and the RT, two syllable oddball paradigms with different degree of difficulty were created. The paradigms were embedded in multitalker babble noise to create a realistic listening situation. The data was collected from 13 normal hearing healthy subjects, who had to detect a deviant. Furthermore, the wavelet phase synchronization stability (WPSS) was calculated for different scales. A filter bank was designed in order to separate the components by their frequency content. Finally, the Pearson product-moment correlation coefficient was calculated to clarify if there is a possible linkage between the RT and the ALR components. The results show, that only the P(3) latency is correlated with the RT. A relation between the RT and the other ALR components could not be observed. It is concluded, that the focus of our further research, will be on the N(1) and the P(2) wave due to the fact that those components are independent from the non- effort related factor reaction time.

Auditory streaming and listening effort: an event related potential study

Until now, an objective method to estimate listening effort with a minimum level of cooperation of the patient in order to fit hearing aids is not existent. The benefit of such a method would be to reduce the listening effort in hearing impaired persons by an adequate adaption of the hearing aids. Recently, we have shown that the wavelet phase synchronization stability (WPSS) of auditory late responses could serve as a measure to estimate listening effort. In this paper, we extend our previous studies by using for the first time syllable stimulation paradigms with two levels of difficulty due to the combination of the syllables. Furthermore, by taking the model of auditory stream selection into account, the complexity of the paradigms was enhanced by the generation of a second competing auditory stream beside the syllable stream. This stream consisted of multitalker babble noise at two different signal to noise ratios in order to mimic noisy environments. The data was collected from a total of 21 normal hearing subjects, who had always to detect a target syllable. It is concluded, that the WPSS is a robust measure to perceive differences between the effort needed to solve a task in an easy and a difficult listening condition. However, a further research will be to test hearing impaired persons to prove, if this electrophysiological method could be applied to improve the hearing aid fitting procedures in clinical settings.