Listening Effort: The hidden costs and benefits of cochlear implants

Speech understanding in ideal listening conditions can seem quite effortless for normal hearing listeners. For deaf people with a cochlear implant (CI), however, the incoming speech is degraded compared to normal hearing due to limitations of the device, the health of the auditory nerve, and the device-nerve interface. Such degraded speech, even when fully intelligible, can be more effortful to interpret than clear speech, especially in challenging conditions, but perhaps even in favorable ones. Although high listening effort is not directly apparent to the outside observer, it has consequences for the listener: high listening effort can lead to difficulties performing concurrent tasks, remembering the correctly heard speech, and may in the long term lead to fatigue and increased stress related sick-leave from work. CI users that experience such problems can therefore benefit from reduced listening effort.

The results of our research show that improved quality of the speech signal, for example due to increased spectral resolution or additional low-frequency acoustic sound, can improve listening effort. Even when speech understanding remains unchanged, either because intelligibility is at ceiling or because it is (artificially) fixed using noise, improvements in listening effort can still occur. This illustrates the importance of measuring listening effort in addition to the traditional measures speech understanding. A reliable measure of listening effort can be useful in scientific research, to investigate which factors affect listening effort and identify effective strategies to improve listening effort, as well as for use in clinical settings, to fit CIs for minimal listening effort.