Editorial

Abstract

Cognitive Hearing Science (CHS) is an emerging discipline concerned with the psychological aspects and neural bases of hearing and deafness. The growth of interest in this field is remarkable (Craik, 2007; Rönnberg & Arlinger, 2008; Pichora-Fuller, 2008; Akeroyd, 2008). Among clinicians there is growing awareness of cognitive issues in relation to hearing disorder and hearing loss (Bamiou & Luxon, 2008). This special anniversary issue of the Scandinavian Journal of Psychology highlights some aspects of CHS, with invited contributions from some leading exponents. Its strongly Scandinavian flavor reflects the unique contribution of local researchers to the field, from its outset (see Arlinger et al., this issue) through to more recent developments (Rönnberg & Arlinger, 2008). In this special issue we solicited contributions from scientists in a variety of disciplines, with varying theoretical perspectives, focusing on some recent empirical findings and their implications within this fast-changing scene. Cognitive psychologists are concerned with the ways in which symbolic and mental representations function in relation to each other. The audiological specialist, by contrast, focuses on the auditory domain -- that of the acoustic signal and its sensory and perceptual registration. How can these domains be integrated? The perspective advocated here is that one way to understand the interpenetrability of signal and symbol is through their implementation in a multiply connected neural processing system -- that is, to develop brain-based models of auditory and language processing (and see Pichora-Fuller & Singh, 2006). This framework may be articulated in terms of hierarchies of processing describing the interaction of top-down (cognitively driven) and bottom-up (signal-driven) processes. This approach is epitomized in this issue by the Ease of Language Understanding (ELU) model, and the papers by Stenfelt & Rönnberg, by Rudner, Foo et al., and by Lunner et al., particularly. However, growing awareness of the extent to which effects can ramify bidirectionally -- and especially how cognitive skills can impact on subcortical auditory mechanisms may be needed to temper some speculations and to drive others (see e.g. Lee, Skoe, Kraus & Ashley, 2009; Banai, Hornickel, Skoe, Nicol, Zecker & Kraus, 2009). More generally, however, it is well established that spoken language can be understood despite extensive distortions and degrading of the acoustic signal. For example, the phoneme restoration effect (Warren, 1970) and sine-wave speech comprehension (Remez, 2008) are phenomena familiar to students of cognitive psychology. The psychologist may not, therefore, be too surprised to learn that the individual cognitive skills of the listener bear strongly on the ability to process the heard signal, but may not appreciate how critical this can be when hearing is compromised (van Rooij, Plomp & Orlebeke, 1989; see Akeroyd, 2008 for review, also Pichora-Fuller & Singh, 2006; Pisoni, 2004; Wingfield & Grossman, 2007). One task for researchers in CHS is to conceptualize and clarify the nature of the cognitive resources and processes brought to bear when auditory abilities do not suffice to support the normal development and application of auditory speech processing. Several different issues and concerns have come to the fore recently which are addressed by the papers in this issue. Some current growth points in research are: Characterization of hearing loss associated with human aging (presbycusis) in relation to individual differences in cognitive processing. Many language skills remain remarkably resilient to aging, so why is there such variability in the efficient processing of speech and language in relation to hearing loss in older people (Wingfield & Grossman, 2006)? Working memory skills appear to play an important role in compensating for some signal processing problems (see Rudner, Foo et al., this issue), but how, exactly? Which further cognitive processes are implicated (Humes & Coughlin, this issue; Rudner, Foo et al., this issue)? How can written tests of cognitive function be used to explore cognitive processes when hearing loss makes signal processing difficult (Kramer et al., this issue)? And how might immediate memory be implicated in another manifestation of auditory dsyfunction: tinnitus (Andersson et al., this issue)? Developments in hearing aid technology. Various signal processing systems and strategies can now be instantiated in modern hearing aids. How can these be optimized? Which aspects of signal change might be positive -- and are there negative aspects too? For which people and for which listening situations (Stenfelt & Rönnberg, this issue; Lunner et al., this issue; Rudner, Foo et al., this issue)? Early-onset deafness in relation to cognitive and cortical plasticity. How does the child born deaf acquire cognitive competencies? Non-verbal IQ is age-appropriate in deaf compared with typically developing children (Marschark, 2007), but the ramifications of early hearing loss can extend far beyond difficulties in speech processing (Fagan & Pisoni, this issue; Peterson, this issue). Hearing impairment may lead to the development of compensatory abilities, with consequent cortical organization that may (or may not) differ from those of people with normal hearing (Auer, Aparicio et al., Kramer et al., Strelnikov et al., all in this issue). Cochlear implantation (CI). The advances in technical and clinical progress for this unique neural prosthesis have been truly remarkable (Wilson & Dorman, 2008). Perhaps the least anticipated, and therefore most remarkable, aspect of the success is in the fact that the very sparse signal delivered by the implant can nevertheless support effective hearing, at least in some recipients. For example, several formerly deaf people with CI can identify heard sentences (in a quiet background) just as well as their hearing peers. Some children born deaf, but with CI in childhood, appear to follow the developmental trajectory for speech perception of the child with normal hearing (Pisoni, 2004). While untreated deafness is a profound impediment to efficient reading development, some (although not all) CI recipients can become efficient readers (Geers, Tobey, Moog & Brenner, 2008, Lyxell et al., this issue). Despite these very positive outcomes, variability in post-implant hearing utility is widely apparent (Geers et al., 2008; Wilson & Dorman, 2008). What are the sources of this variability, and how might they be related to cognitive strategies and processes? Strelnikov et al. (this issue) offer one possible explanation. Multimodality of speech. Since speech is often seen as well as heard, speechreading can offer insights into speech processing mechanisms, especially when hearing is compromised. Seen speech contains few cues for easeful speech comprehension but, nevertheless, some (deaf) individuals show remarkable speech processing capabilities “by eye” (Andersson & Lidestam, 2005; Rönnberg, Andersson, Samuelsson, Söderfeldt, Lyxell & Risberg, 1999). What are the characteristics of the seen-to-be-spoken utterance that enable the viewer to identify the critical features of the spoken message? Lidestam (this issue) and Auer (this issue) explore different aspects of this skill. How, in someone with a history of hearing impairment, might relative reliance on seeing speech affect their speech processing when hearing is restored? Strelnikov et al. (this issue) address this question The papers collected in this special issue illustrate some facets of an emerging new discipline: Cognitive Hearing Science. What direction will research in this area take in future? First, we believe that implicit methods -- both behavioral and neurophysiological, will make a strong impression on the field and enable the researcher to develop stronger models of the relationship between explicit test/task responses (for example in reading span tasks, or identifying speech in noise) with implicit measures of activity related to the variable under test. Secondly, as neural models of auditory function become richer, so they will provide an articulated organizing framework for many of the phenomena described here (Friston, 2005; Scott & Johnsrude, 2003). This process is, of course, already underway in relation to degraded hearing (Obleser, Wise, Dresner & Scott, 2007; Pichora-Fuller, 2008; Wingfield & Grossman, 2007). As we have pointed out, several studies suggest that the (neural) components of audition may be remarkably sensitive to modulation from other modalities or from higher cognitive processes -- that is, ideas about signal specificity and about plasticity will become more sophisticated. More developments on the technology front, including earlier and more bilateral CI in deaf infants as well as more sophisticated signal manipulations in digital hearing aids, are likely to change the picture further, and lead researchers to develop new ideas concerning the ways in cognitive and neural plasticity impact on the success of such technologies -- and vice-versa. These continued technological advances, along with those at the scientific (especially genetic and neural) level, are also likely to impact on social and cultural issues, for example, through changes in effective communication with the “able-hearing” community. Deaf identity, often defined by sign language use, and by special educational and cultural practices, is likely to change as more deaf children with effective hearing instruments become adults. Similarly, effective strategies for intervention in presbycusis should lead to greater inclusion of elderly people in active communities. Such positive clinical outcomes will generate new research issues to be addressed by Cognitive Hearing Science. A special thanks to Elisabet Classon for her valuable support in cross-referencing work in this issue.