Listening in aging adults: from discourse comprehension to psychoacoustics

Older adults, whether or not they have clinically significant hearing loss, have more trouble than their younger counterparts understanding speech in everyday life. These age-related difficulties in speech understanding may be attributed to changes in higher-level cognitive processes such as language comprehension, memory, attention, and cognitive slowing, or to lower-level sensory and perceptual processes. A complicating factor in determining how these sources might contribute to age-related declines in speech understanding is that they are highly correlated. Experimenters have typically focused either on cognitive declines or sensory declines in artificially optimized test conditions. In contrast, our approach focuses on the complex interactions between age-related changes in cognitive and perceptual factors that affect spoken language comprehension, especially in nonideal, realistic conditions. In this article, we describe our attempts to systematically investigate sensory-cognitive interactions in controlled experimental situations. We begin by looking at experimental conditions that closely approximate everyday listening, and show that older adults do indeed experience deficits in spoken language comprehension relative to younger adults in these conditions. We then review further experiments designed to isolate more precisely the cognitive and perceptual sources of these age-related differences and how they vary with listening condition. In large part, we find that age-related changes in speech understanding are a consequence of auditory declines.