Auditory Processing and Understanding Speech
I think we all know that our hearing tends to get worse as we age. But
did you know that a slowdown in auditory processing also contributes to a
declining ability to understand speech?
July 2007 - The Aging Auditory System and Understanding
Speech - Part 1
September 2007 - The Aging Auditory System, Part 2:
Slower Processing and Speech Recognition
September 2007 - Neuroimaging and Cochlear Implants: A
Look at How the Brain Hears
September 2007 - The Aging Auditory System, Part 3:
Slower Processing, Cognition, and Speech Recognition
November 2007 - Auditory
Rehabilitation and the Aging Brain
December 2007 - Mapping the selective brain
January 2008 - How the Auditory Cortex Processes
Sound
May 2008 - Peripheral, Central-Auditory, and Cognitive
Factors Affecting the Speech-Understanding Problems of Older Adults
June 2008 - Negative Synergy: Hearing Loss and Aging
June 2008 - Changes in Central
Auditory Pathway for Tinnitus Sufferers?
July 2008 - Hearing Test May Measure Cognitive Decline
November 2008 - Auditory Processing in Adults: Beyond the
Audiogram
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July 2007
Evidence for slower processing at and below the
brainstem level using objective measures
This article is the first of a three-part series
on the aging auditory system, and it provides evidence of slower
processing from studies that used objective measures unaffected by
attention or memory. In the second article, evidence for slower processing
within the higher (ie, above the brainstem) auditory pathways is reviewed.
Additionally, the relationship between slower processing and speech
recognition is examined. In the third article, the complex
interrelationships of slower processing, cognition, and speech recognition
are examined.
The series is designed to provide an overview of
how speech recognition in older individuals is affected by both slower
processing and cognition. In particular, such an understanding can lead to
more effective aural rehabilitation services for older adults.
http://www.hearingreview.com/issues/articles/2007-07_09.asp
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September 2007
This article is Part 2 of a three-part series on
the aging auditory system, and it reviews the evidence for slower
processing within the higher (ie, above the brainstem) auditory pathways,
whereas Part 1 examined evidence of slower processing from studies that
used objective measures unaffected by such things as attention or memory.1
Additionally, the present article will look at the relationship between
slower processing and speech recognition. In Part 3, which will be
published in next month's HR, the complex interrelationships among slower
processing, cognition and speech recognition are examined. It has been
generally established that, with aging, individuals experience a decreased
ability to recognize rapid speech, even in the presence of normal hearing.
The resulting communication difficulties, social isolation, and depression
can contribute to an overall decrease in the quality of life.
Full Story
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September 2007
Hearing scientists use neuroimaging techniques,
which examine how the brain responds to external acoustic stimuli, to
evaluate auditory processing. Investigators may probe how the brain
responds to simple manipulations of frequency, intensity, or duration of
the stimuli, or they may investigate how the brain responds to more
complex listening conditions such as the appreciation of music, the sounds
of familiar or unfamiliar languages, or the perception of speech signals
in noise. A growing literature focuses on learning how individuals with
normal hearing or hearing loss process the sounds in their environment and
the sounds needed to communicate. Two uses of neuroimaging techniques are
in examining processes contributing to tinnitus and other annoying
auditory conditions, and examining conditions in which an acoustic signal
is transposed into an electrical stimulus such as a cochlear implant (CI).
Several studies with individuals with cochlear implants concentrate on how
the brain uses cortical resources to perceive speech or music. This
information helps determine ways to improve the integrity of an electrical
signal representing speech and to train people with cochlear implants to
improve their listening performance
Full Story
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September 2007
In the final article in a three-part series, the
author looks at the complex interrelationships between slower processing,
cognition, and speech recognition in an effort to determine what this
means relative to the elements of a comprehensive aural rehabilitation
protocol for adults. With aging, individuals experience a decreased
ability to recognize speech, even when they have normal hearing acuity.
This difficulty is more obvious when the speech is presented at a fast
rate or is presented in the presence of competing signals. Two of the
possible underlying mechanisms for poor speech recognition in older
individuals include reduced speed of signal processing within the auditory
pathways and/or reduced cognition. Parts 1 and 2 of this series of
articles presented evidence showing slower processing within the higher
auditory pathways and its relationship to speech recognition. Age-related
changes in brain structure and function may contribute to poor sensory and
cognitive function. Alternatively, cognitive declines may be a consequence
of degraded auditory processing, causing sensory deprivation. Thus, a
complex inter-relationship among speech recognition, cognitive
performance, and slower processing can be expected. Part 3, the final
article in the series, examines this complex inter-relationship. An
in-depth understanding of these relationships can be expected to lead to
more effective aural rehabilitation services for older individuals.
Full Story
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May 2008
In addition to these two versions of the
peripheral hypothesis, the CHABA report identified two potential
contributing mechanisms that go beyond the auditory periphery. The first,
the central-auditory hypothesis, theorizes age-related deterioration in
the ascending pathways of the auditory portions of the central nervous
system-from the cochlear nucleus through the primary auditory cortex. The
second, the cognitive hypothesis, conjectures age-related declines in
amodal processes at the cortical level, such as information storage and
retrieval (memory) and attention. Although both of these hypotheses are
"central" or higher-level than the peripheral hypothesis, they differ from
each other in at least two important ways. First, the central-auditory
hypothesis includes brainstem and cortical structures, whereas the
cognitive hypothesis is operational at the cortical level only. Second,
the central-auditory hypothesis is modality-specific and plays a role only
for the auditory presentation of speech stimuli, whereas the cognitive
hypothesis affects mechanisms such as memory, attention, and linguistic
knowledge that are not specific to auditory input and may involve many
regions of the brain.
Full Story
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June 2008
Basic audiometric measures do not offer a
comprehensive description of the speech understanding ability or
difficulty of patients. Speech understanding is complex and complicated.
Individual cognitive abilities (intelligence, language, vocabulary,
psychological profile, etc.) as well as audiologic and medical histories,
genetic make-up, first- and second-language issues and other factors
impact our ability to understand speech, particularly in challenging
acoustical environments. . . . This paper will address speech
understanding from cognitive (top-down) and sensory-based (bottom-up)
perspectives, highlighting the interactive and complimentary relationship
required for successful communication.
Full Story
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July 2008
Central auditory testing may act as an early
screen for cognitive decline in the elderly, researchers here said. In a
study of 313 patients at least 71 years old, several measures of central
auditory processing were impaired in those diagnosed with Alzheimer's
disease and, to a lesser extent, those with memory impairment but not
meeting criteria for Alzheimer's, reported George A. Gates, M.D., of the
University of Washington, and colleagues in the July issue of Archives of
Otolaryngology and Head and Neck Surgery. Central auditory processing is
the brain function involved in interpreting complex sounds such as speech.
"Hearing speech involves detection, recognition, and comprehension, the
latter being clearly a cognitive task," said Dr. Gates. Such hearing
problems often show up as an inability to understand speech against a
background of other conversations, sometimes called the "cocktail party
effect." Amplification with hearing aids does not help this form of
auditory defect.
Full Story
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November 2008
Audiologists are faced daily with patients who
report communication issues that they may attribute to hearing loss. These
types of communication issues may include difficulty hearing in less than
optimal listening situations, reliance on visual information to augment
auditory information, a reduced appreciation of listening to music, and
difficulty understanding speech when the speaker is unfamiliar. Patients
report that these communication issues impact the quality of their lives-
often the reason for seeking audiology services. For many of these
patients, the results of an audiologic evaluation are consistent with a
peripheral hearing loss, and the findings of the evaluation help to direct
audiologic treatment to address these communication difficulties or to
direct recommendations. However, some patients who present with concerns
will demonstrate normal peripheral hearing acuity based on the results of
standard audiometric testing. The assumption is often made that because
the results of the audiogram are consistent with normal peripheral hearing
acuity, the person's reported concerns are not validated. The purpose of
this paper is to address the need to look beyond the audiogram to further
validate the concerns raised by the patient.
Full Story
