Restoration of Spectral Resolution With Hearing-aid Amplification
Phase: NA
Conditions: Hearing Loss
Sponsor: University of Nebraska Lincoln

Restoration of Spectral Resolution with Hearing-aid Ampliﬁcation 
 
NCT03850678 
 
Study Protocol and Analysis Plan 
 
March 13, 2019 
 
 
 

Brief Summary  
 
The objective of this study protocol is to determine the e6icacy of using aided measures of 
spectral resolution to set the dynamic range of hearing with hearing-aid ampliﬁcation. 
Measures of spectral resolution will be obtained, as will measures of speech recognition.  
 
Signiﬁcance/Purpose: 
 
Adults with hearing loss are more vulnerable to interference from background noise than 
adults with normal hearing. Despite the fact that the ability to extract speech information 
imbedded in background noise requires decoding di6erences in level across frequency 
(spectral information), few studies have addressed the extent to which we can provide 
spectral information to listeners with hearing loss. This fundamental gap in our knowledge 
prevents us from e6ectively addressing the systemic e6ects of hearing loss on 
communication, income, and ability to socialize with others. This work is a new application 
of established methods of characterizing spectral resolution to that of the most common 
device for rehabilitation of hearing loss—hearing-aid ampliﬁcation. The proposed 
experiments will examine the degree to which access to spectral information can be 
restored to adults with hearing loss and the feasibility of utilizing this information to 
decrease interference from background noise. Aim 1 will delineate the impact of hearing-
aid ampliﬁcation on spectral decoding. Technology options that must be set by the 
clinician or hearing-aid manufacturer will be examined, including the frequency-speciﬁc 
gain, compressor speed, and number of compression channels. The proposed 
experiments will test the hypothesis that restoration of the lost dynamic range of hearing 
can support the encoding of spectral information. It is also hypothesized that the 
combination of technology options that best restore access to spectral information will 
di6er across individuals and that these di6erences across individuals can be partially 
accounted for by an estimate of outer hair cell function. Aim 2 will determine the extent to 
which restoring access to spectral information supports speech recognition in background 
noise, under the guiding hypothesis that improving spectral resolution increases speech 
understanding. If it can be demonstrated that measures of spectral resolution with the 
provision of ampliﬁcation are useful at delineating those who stand to beneﬁt from 
di6erent technology options, the knowledge gained could then be applied to the clinic to 
allow for clinicians to more successfully choose among di6erent rehabilitation options.  
 
 
Study Design 
 
Data Collection Procedures: 
 
This study can be divided into 4 sections. For all four sections, the subject will sit in a 
sound attenuated booth.  
 

Section 1 - Questionnaire and cognitive impairment screen 
 
At this time, each subject will complete a questionnaire that asks relevant questions about 
their medical and developmental history and educational level. Participants will be 
screened for a potential cognitive impairment using the Montreal Cognitive Assessment 
Basic (MOCA-B). The MOCA-B is a 10-minute cognitive screening tool to detect mild 
cognitive impairment. Participants are asked to perform tasks including connecting 
numbers and patterns on a sheet of paper, recalling words, naming of items, and simple 
math calculations. Participants with a score less than 26 will be informed of the test results 
and counseled to consult with their primary care physician. A screening for potential 
cognitive impairment is being implement to limit the possible inﬂuence (i.e. confound) of 
cognitive impairment on our perceptual results.  
 
Section 2 - Audiological test and hearing aid ﬁtting 
 
Each subject will undergo a routine audiological examination. First an audiogram will be 
completed. The subject will hear a series of acoustic beeps. The subject's task is to 
indicate when he or she heard a beep. From this test we can determine the softest sounds 
that the subject can hear. This will be completed using an audiometer (sound presentation 
device) and earphones. The earphones will be attached to the subject. Each subject will be 
ﬁtted for testing with hearing aids or a computer based hearing aid simulator. 
Tympanometry, a routine audiological test, will be completed.  
 
Section 3 - Detection of Acoustic Information 
 
We will measure the ability of the subjects to detect small changes in the frequency of the 
signal. Via a touchscreen, the subject will indicate when he or she heard a change in the 
signal, from which a threshold is estimated. This measure is related to the perception of 
speech.  
 
Section 4 - Speech Recognition 
 
Speech sounds will be presented at a variety of levels. The subject will repeat back the 
speech sounds that they heard and their spoken response will be scored.  
 
Test Time: 
 
The audiological test and hearing aid ﬁtting is anticipated to take 1 hour to complete. 
Section two is anticipated to take approximately 3 hours and section three approximately 2 
hours. Participants with NH require less time; they are not ﬁt with hearing aids and undergo 
fewer conditions. In addition to hearing status, the duration will depend on how quickly 
each subject completes the study and on whether a current audiological test can be used, 
thereby saving time. Consequently, we anticipate the study will take approximately 3-6 

hours per subject. Generally subjects complete the study in 2-3 sessions scheduled over 
the course of a couple weeks.  
 
Recruitment: 
 
Recruitment will occur at the Barkley Speech, Language, and Hearing Clinic, Lincoln and 
surrounding community facilities that provide audiological or ear nose throat services, and 
through organizations with older individuals (e.g. OLLI at UNL). Participation will take place 
at the ampliﬁcation and perception laboratory.  
 
 
Statistical Analysis: 
 
We plan to enroll 20 subjects with normal hearing and 40 subjects with sensorineural 
hearing loss (per experiment). While we plan to recruit the same subjects for each 
experiment, additional subjects will be recruited as needed. Additional subjects will be 
recruited for pilot testing and to account for attrition. We expect an e6ect size of 0.37 (ηp2) 
or greater. Using G*Power (v3.1) we estimated sample sizes necessary to detect an e6ect 
size of over 0.23 (power = 80%, α = 0.05). For Aim 1, planned comparisons to examine the 
e6ect of prescriptive procedure, compression speed, and number of compression 
channels on the sharpness of tuning measured will be conducted using an ANOVA or, if we 
ﬁnd that the assumptions of the ANOVA to be violated, a linear mixed e6ect model. For Aim 
2, planned comparisons to examine the e6ect of dynamic range of hearing (small, large) 
and tuning status (poor tuning, sharp tuning) on proportion correct will be conducted using 
an ANOVA or, if we ﬁnd that the assumptions of the ANOVA to be violated, a linear mixed 
e6ect model. While results are not expected to di6er by sex, di6erences by sex will be 
analyzed for all experiments. Other variables, such as age, degree of hearing loss, and 
working memory likely play a role in spectral resolution and speech recognition and will be 
considered as variables in our statistical models.