Auditory Training, Cognitive Training, and Distortions: Interview with Helen Henshaw, PhD
Douglas L. Beck,AuD, spoke ith Dr. Henshaw about hearing loss, auditory training, cognitive training, distortions, dementia, cognitive decline, and more.
Douglas L. Beck (DLB): Hi, Helen. It’s a pleasure to chat with you. If I recall, your background is in experimental cognitive psychology, and in particular you’ve studied visual memory with regard to object location and the accuracy of memory. Of note, since 2009, you’re working with my friend and colleague (Mel Ferguson) on applying your knowledge and experience to successful listening and the role of cognition?
Henshaw: Yes. That’s right. We’re looking at how to support people with hearing loss through translational research. So we take discoveries from basic science and we adapt and apply them to knowledge and interventions that can be used by the public and in clinical practice through proven and outcomes-based protocols. I work alongside Mel Ferguson, who is the lead for the Habilitation for Hearing Loss research group at the NIHR Nottingham Biomedical Research Unit. The group is termed habilitation rather than rehabilitation to reflect the incurable (but manageable) nature of hearing loss.
DLB: Very good. Please tell me a little more about the research of the Habilitation for Hearing Loss research group?
Henshaw: Our research focuses on assessing novel and existing interventions to help alleviate hearing related difficulties. There are three research strands: (1) patient education aims to improve knowledge about hearing loss and hearing aids and about the difficulties faced, (2) patient motivation explores the patient-clinician relationship and health-behavior change, and (3) audition and cognition is my personal research, focused on and includes training interventions to help improve communication outcomes. All of our research is underpinned by a number of core considerations such as involving communication partners (communication is a two-way street, right!), identifying optimal intervention delivery methods and choosing appropriate and sensitive outcome measures to detect patient benefit.
DLB: And can you tell me a little about your auditory and cognitive training research?
Henshaw: I’m glad you asked! Well, for auditory training interventions to benefit people with hearing loss, any task-specific learning needs to generalize to functional benefits in their real-world listening. Mel and I recently published a systematic review of studies examining computer-delivered auditory training for people with hearing loss. Results suggested that although training showed some promise for generalized improvements, published evidence ranged between very-low to moderate study quality, highlighting the need for further high-quality research in this area. We have since completed two high-quality studies of phoneme discrimination training for adults with mild-moderate sensorineural hearing loss. The first study examined the benefits of training as an intervention for a pre-hearing aid population. The second identified appropriate and sensitive outcome measures to demonstrate benefit. In addition to speech perception outcomes, we investigated the cognitive benefits of this type of intervention. Results showed significant generalized post-training improvements in self-reported hearing, working memory, divided attention, listening effort and in individual’s ability to perceive competing speech. The benefits shown were greatest for complex task conditions, where the cognitive demands of listening were high.
DLB: So what’s next?
Henshaw: Well, given the results of our auditory training research we carried out a third study to assess whether training cognition directly would offer a more direct route to those patient benefits. We have recently completed this working memory training study using Cogmed (no one has studied this in hearing aid patients so it is novel) and are currently analyzing the results. Unfortunately, I can’t say anything about the results yet, but I can say they are giving us a clear steer as to where we go next with training.
In the meantime, we have just begun a James Lind Alliance Priority Setting Partnership for mild-moderate hearing loss. The James Lind Alliance is an NIHR initiative which aims to identify unanswered questions and prioritize them for research. Its name sake, James Lind was a Scottish naval surgeon and a pioneer of clinical trials. He tested six proposed remedies for scurvy to find the most effective treatment, and settled on citrus fruits!
DLB: Let me ask your thoughts on the key elements of auditory rehabilitation?
Henshaw: That’s a strikingly simple question with a profound and robust range of possible answers! First, I should think the key elements vary, because each patient is an individual, and if we group them for our purposes (such as “mild hearing loss”) we lose information about the individual and we also add our own interpretation of the same group! And so what I’m saying is we need to realize and appreciate that the individual is our participant/patient or our concern, and we must conduct our experiments and analysis with the same mind-set. As you know, different people with the same diagnosis, or the same type and degree of hearing loss are most likely to present with different degrees of hearing difficulty, and therefore may respond differently to the same interventions. And so to me, the answer to your question is that the key element of auditory rehabilitation is to completely understand the difficulty the person is having, and applying, a unique solution which meets their personal needs.
DLB: The whole concept of “personalization” is actually a huge topic right now in clinical audiology across the world. In fact, I define “personalization” very much in accordance with what you’ve just stated, “personalization is solving the problem the patient perceives.”
Henshaw: Yes, and of note, they don’t come to see hearing professionals because they have hearing loss, they come to see hearing professionals because their hearing loss is preventing them from communicating–and it’s the communication problem one needs to address!
DLB: I agree. Most hearing care professionals try and make things louder—and that’s a very small part of the problem. The larger component is their inability to organize the sounds around them, so their brain can maximally interpret and use the sounds to listen to speech in noise, to understand and to communicate! But I feel like I’m preaching to the choir.
So then, let’s move on to your thoughts, as a psychologist, with regard to dementia and in particular, are you aware of anything which may slow or stop cognitive decline? Frank Lin reported in June 2013 in the JAMA that “hearing loss is independently associated with accelerated cognitive decline and incident cognitive impairment in older adults. However, further studies are needed to investigate the mechanistic basis of this association and whether hearing rehabilitative interventions would affect cognitive decline….” Your thoughts?
Henshaw: Well, there’s arguably a Nobel Prize in the correct answer to that one! However, what we know in 2014 is essentially the same. That is, some cerebral and cognitive challenges and mental exercises appear to be helpful for some people with regard to delaying dementia, but nothing is 100 percent. As you know, Doug, there are a number of organizations looking into whether or not applying hearing aid amplification to a person with hearing loss and dementia will alter the ultimate outcome, but there are not substantial or statistically meaningful studies out there yet (of which I am aware!) and so we have to wait for the results to come in before we can appropriately answer the question, and it may take another 5 to 7 years!
DLB: I agree. However, if I were to be bold and ask your thoughts, opinions and suspicions, as they relate to the vast links between cognition and audition, what would you tell me?
Henshaw: Well, if I were to speculate, I would say it’s important to first understand the independent mechanism that drives the co-morbidity between hearing loss and dementia. For example, if they’re both secondary to physical changes and problems, then amplification isn’t likely to drive a change towards cognitive improvement. However, if both processes are secondary to sensory deprivation, then amplification would appear to be a primary driver of cognitive improvement.
DLB: Thinking back to the research you are involved in with people with mild-moderate hearing loss, when might hearing aids and sound processing work well with respect to cognition, and when might they be less effective?
Henshaw: Evidence has shown that in general, if you use an aggressive processing strategy for people with excellent cognitive abilities, their cognitive systems can accommodate that aggressive processing and provide an excellent result. Further, if you use an excellent noise reduction program, you reduce the amount of cognitive effort the brain has to provide, and you increase the ease of listening. Doug, one point you’ve made time and time again is that all noise reductions programs aren’t the same, and all hearing aid directionality programs aren’t the same!
DLB: Yes, well that’s apparent to me from reading and reviewing the literature…when we group together all “noise-reduction” or “adaptive-directionality” or “frequency-lowering” processes and protocols, we quickly approach a discussion which is too vague to have meaning, and the lost details contaminate any qualitative or quantitative discussion of outcomes.
Henshaw: Yes, and another thing which is key to me, is distortion. Simply, as distortion decreases, fewer cognitive demands are made. Indeed, one might say, as distortions increase, cognitive demands increase in order to make sense of sound.
DLB: And of note, when we apply loudness compression and/or spectral compression, it seems to me, we’re actually distorting sounds further, not in a nasty way or with misguided intention, indeed, we do so with the very best intentions—but then we’re placing these intentionally distorted sounds into an ear, which came to visit us because it too, has distortion and cannot make sense of or organize sounds.
Henshaw: Yes, I would agree. It’s important to understand that the brain seeks natural, clean and well maintained, undistorted sensory input!
DLB: Okay then…Helen, you’ve been very generous with your time and I am very appreciative of your time and knowledge.
Henshaw: My pleasure, Doug. Thanks for your interest in our work!
Helen Henshaw, PhD, is a senior research fellow at the National Institute for Health Research (NIHR), Nottingham Biomedical Research Unit, in Nottingham, England.
Douglas L. Beck, AuD, Board Certified in Audiology, is the Web content editor for the American Academy of Audiology and the director of public relations with Oticon, Inc.