Speech masking effects in speech communication across the lifespan

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Our ability to communicate successfully with others can be strongly affected by the presence of noise and other voices in the environment, and children and older adults are more greatly affected than young adults in these situations. Even greater disruption is experienced for populations with hearing or language impairments, or even healthy adults who are non-native speakers. Some of the disruption is due to physical masking by interfering sounds (energetic masking EM) but if the disrupting sound can be understood, this also causes further difficulty (informational masking IM). Previous work suggests that informational masking causes relatively more disruption for children and older adults than for young adults but these findings are based on laboratory tests that are far from realistic communication.Although the impact of adverse conditions on speech communication has been the object of studies in different age groups, no study to date has taken a full lifespan view, looking at the relative impact of IM and EM on participants aged from 8 to 85 using a common experimental design. Also, many studies have focused on the impact of EM and IM on speech perception using recorded sentences or words; this ignores the fact that speakers make dynamic adaptations in speech communication to counter the effects of masking. We evaluate the impact of adverse conditions in an interactive task using measures reflecting speech communication efficiency (e.g., task transaction time, rate of dysfluencies). Finally, there is little evidence to date as to whether laboratory-based evaluations reflect the level of difficulty experienced in everyday life. The proposed project will, for the first time, relate evaluations of speech communication difficulties in adverse listening conditions as measured in the laboratory with real-life ratings of difficulty collected in real time over a two week period. It will also test whether primarily informational masking causes greater interference for some age groups (e.g. children, older adults), and if the underlying reasons for the interference differ between children and adults.In Study 1, 120 individuals aged 8 to 85 yrs will be tested in pairs while they carry out a problem-solving task in conditions varying in the degree of informational and energetic masking present. A secondary task will be added to make the task more cognitively demanding, thus reflecting real-life multitasking situations. Baseline measures of hearing, speech perception and cognitive function and a standardised questionnaire of auditory disability (SSQ) will also be collected. In Study 2, the same participants will be asked to report perceived communication difficulty and their listening environment on 6-7 occasions per day during a 2-week period using a smartphone-based app. Data from this study will be related to measures of communication effectiveness and SSQ data collected in Study 1. Finally, in Study 3, spontaneous speech will be collected for a group of 4-7 year olds using the same interactive task to complement measures from our previous corpora (and data for Study 1) and gain a full lifespan set of acoustic descriptors for conversational speech in good listening conditions. This project will lead to a better understanding of how the impact of adverse listening conditions changes across the lifespan, of the relative effects of IM and EM in different age groups, evaluated in realistic communicative conditions, and of the true ecological validity of laboratory-based evaluations. It will also provide normative data for a set of acoustic-phonetic measures across a 4-85 year age range. This benchmark will be of use for practitioners such as speech and language therapists and audiologists who work on aspects of communication with individuals of all ages. Importantly, this research will also contribute to our basic understanding of speech perception and production development across the lifespan.