Speech comprehension in noise—considerations for ecologically valid assessment of communication skills ability with cochlear implants

BACKGROUND: Nowadays, cochlear implant (CI) patients mostly show good to very good speech comprehension in quiet, but there are known problems with communication in everyday noisy situations. There is thus a need for ecologically valid measurements of speech comprehension in real-life listening situations for hearing-impaired patients. The additional methodological effort must be balanced with clinical human and spatial resources. This study investigates possible simplifications of a complex measurement setup. METHODS: The study included 20 adults from long-term follow-up after CI fitting with postlingual onset of hearing impairment. The complexity of the investigated listening situations was influenced by changing the spatiality of the noise sources and the temporal characteristics of the noise. To compare different measurement setups, speech reception thresholds (SRT) were measured unilaterally with different CI processors and settings. Ten normal-hearing subjects served as reference. RESULTS: In a complex listening situation with four loudspeakers, differences in SRT from CI subjects to the control group of up to 8 dB were found. For CI subjects, this SRT correlated with the situation with frontal speech signal and fluctuating interference signal from the side with R(2) = 0.69. For conditions with stationary interfering signals, R(2) values <0.2 were found. CONCLUSION: There is no universal solution for all audiometric questions with respect to the spatiality and temporal characteristics of noise sources. In the investigated context, simplification of the complex spatial audiometric setting while using fluctuating competing signals was possible.