Auditory Rehabilitation-A Multidisciplinary Approach

This special issue of Seminars in Hearing is a publication that has arisen out of the national conference that was organized by the National Center for Rehabilitative Auditory Research (NCRAR) in Portland, Oregon. The conference was titled “Auditory Rehabilitation: A Multidisciplinary Approach” and took place on October 9 and 10, 2003, in downtown Portland. The conference was attended by over 164 delegates, among whom were audiologists, researchers, engineers, and university faculty from across the United States and Europe. The conference brought together internationally respected clinical researchers and practicing clinicians who discussed the latest advances in the field of auditory rehabilitation with the aim of facilitating learning and scientific discussion.

The meeting had four special sessions that were selected by the Program Committee to represent pertinent issues in the field of clinical audiology. We invited two world-renowned researchers to present at each special session. In addition, between one and three case studies pertinent to the particular session topic were presented by practicing audiologists. These case presentations were submitted by clinicians from around the country and were selected for presentation by the Program Committee based on their clinical and scientific relevance to the session topic. Finally, to end each special session there was an hour-long roundtable discussion during which panel members responded to questions posed by members of the audience. Each discussion session had a different panel. Members consisted of the invited speakers for each session plus one or two other conference participants who had particular clinical and/or research experience in the area under discussion. These panel discussions gave rise to interesting exchanges between panel members and the audience. This special issue consists of a written form of each presentation and case study, along with a transcription of each roundtable discussion. Two special issues of Seminars in Hearing are devoted to this conference. This issue focuses on Advanced Hearing Aid Features: Directional Microphones and Telecoils.

The first session was on directional hearing aids. The opening talk was by Todd Ricketts of the Department of Hearing and Speech Sciences at Vanderbilt University. Dr. Ricketts provided us with an introduction to directional technology and then described for us a series of experiments he has been conducting in his laboratory comparing the benefits provided by adaptive and fixed directional hearing aids for understanding speech in noise. It was particularly enlightening to learn of the practical difficulties that he and his research team have encountered when trying to provide a moving noise source required for investigating the effectiveness of adaptive directionality! He has shown that adaptive directionality does provide a substantial advantage over fixed directionality in very specific listening situations. However, he warns that these situations, in which there are discrete uniform low-level noise sources, may not be very common in the real world.

Dr. Brian Walden of Walter Reed Army Medical Center presented the second paper on directional hearing aids. His presentation specifically addressed the question of the effectiveness of directional hearing aids in real-world listening. He began by pointing out how real-world listening differs from laboratory listening, highlighting such factors as reverberation, variable noise sources, and the need for the user to switch between microphone modes. He presented data showing that many individuals fail to use their hearing aids in the directional mode, and that many had difficulties determining listening situations in which directional microphones would be more advantageous than omnidirectional microphones. He concluded by stating that although directional microphones provide advantages in specific listening situations, omnidirectional microphones should be the default setting for most hearing-impaired individuals.

The final session of the conference was Issues associated with telephone use and hearing aids. Dr. Harry Levitt and Dr. Mark Ross presented different perspectives on this matter. Dr. Levitt’s presentation focused on electromagnetic interference in hearing aids. He described the background behind a new ANSI standard for measuring and specifying the electromagnetic field generated by a wireless telephone and the immunity of a hearing aid relative to the electromagnetic field. He then described an experiment that he and coworkers had conducted to determine how much interference is acceptable to hearing aid users in terms of telephone usability. The research team evaluated three different telephone transmission technologies with several different hearing aid styles from a variety of manufacturers. They found that signal-to-interference ratios (SIR) had to be in the range of 28 to 32 dB to achieve a rating of “highly usable” and that once the SIR dropped to 12 to 15 dB, subjects reported major limitations in usability. These data are important because they provide a relationship between the physical measurement of SIR and subjective usability ratings. Dr. Ross provided a history of the telecoil (or “audiocoil,” as he believes it should be termed), pointing out that the name “telecoil” implies it only has application for telephone use, while it actually has many applications. Uses include performing as receivers in large area loop systems and countertop portable loop systems. Dr. Ross indicated that audiologists should adjust the frequency response of the telecoil to meet that of the microphone, which, he points out, is almost never done in clinical practice. Finally, he explained that in Europe, loop systems are ubiquitous in public places and much appreciated by hearing-impaired individuals.

The case presentations bring much of this information to life and the roundtable discussions allow the reader to eavesdrop on conversations between some of the most informed individuals in the field related to these topics.

The next NCRAR conference is scheduled for September 22 and 23, 2005. It is titled “The Aging Auditory System: Considerations for Rehabilitation.” It will feature presentations from Bob Frisina, Jr. and Jack Mills on pathophysiology of the aging auditory system; Sandra Gordon-Salant and James Jerger on behavioral studies of auditory aging; Kathleen Pichora-Fuller and Arthur Wingfield on cognitive components to auditory aging; and finally from Pam Souza and Therese Walden on amplification and beyond: issues associated with treating the geriatric patient. The keynote speaker will be Moc Bergman from Isreal.