Elevated Pure-tone Thresholds Research Articles

Elevated Pure Tone Thresholds Are Associated with Altered Microstructure in Cortical Areas Related to Auditory Processing and Attentional Allocation.

Hearing loss is associated with cognitive decline and increased risk for Alzheimer's disease, but the basis of this association is not understood. To determine whether hearing impairment is associated with advanced brain aging or altered microstructure in areas involved with auditory and cognitive processing. 130 participants, (mean 76.4±7.3 years; 65% women) of the Rancho Bernardo Study of Healthy Aging had a screening audiogram in 2003-2005 and brain magnetic resonance imaging in 2014-2016. Hearing ability was defined as the average pure tone threshold (PTA) at 500, 1000, 2000, and 4000 Hz in the better-hearing ear. Brain-predicted age difference (Brain-pad) was calculated as the difference between brain-predicted age based on a validated structural imaging biomarker of brain age, and chronological age. Regional diffusion metrics in temporal and frontal cortex regions were obtained from diffusion-weighted MRIs. Linear regression analyses adjusted for age, gender, education, and health-related measures. PTAs were not associated with brain-PAD (β= 0.09; 95% CI: -0.084 to 0.243; p = 0.34). PTAs were associated with reduced restricted diffusion and increased free water diffusion primarily in right hemisphere temporal and frontal areas (restricted diffusion: βs = -0.21 to -0.30; 95% CIs from -0.48 to -0.02; ps < 0.03; free water: βs = 0.18 to 0.26; 95% CIs 0.01 to 0.438; ps < 0.04). Hearing impairment is not associated with advanced brain aging but is associated with differences in brain regions involved with auditory processing and attentional control. It is thus possible that increased dementia risk associated with hearing impairment arises, in part, from compensatory brain changes that may decrease resilience.

Probability Distributions for Associations Between Cognitive Screening and Pure-tone Thresholds in Older Adults.

Lower general cognitive function is frequently reported in older adults with elevated pure-tone thresholds. Here, we examined reason(s) for this association, including whether this relationship is dependent on the frequency range or extent of hearing loss and cognitive screening performance. Linear regression was used to examine associations between better-ear pure-tone thresholds and Mini-Mental Status Exam (MMSE) performance in a cross-sectional sample of relatively healthy older adults (N = 508; 68% women, 60-89+ years; M age = 72). Quantile regression was also used to identify the ranges of 0.5 and 4.0 kHz thresholds and MMSE scores where these variables exhibited significant associations. MMSE scores and pure-tone thresholds exhibited small but significant associations, particularly for better-ear 0.5 kHz thresholds. This hearing threshold and cognitive screening association was present among participants with better hearing, including the oldest older adults. There was limited evidence for mediating health condition effects on this association. An item analysis of the MMSE revealed that the MMSE and pure-tone threshold associations were largely due to the delayed recall item of the MMSE. Together, the small effect results are consistent with the extant literature and suggest that there are multiple reasons for modest pure-tone threshold and cognitive screening performance associations.

Prevalence of Hearing Loss, and Middle Ear Disease in 1351 School Age Children in Mekelle, Ethiopia.

The objective of this study was to begin to measure the prevalence of elevated hearing thresholds in Ethiopia, with audiometric equipment, including bone oscillators and tympanometers. To that end Ethiopian nationals were trained in audiometric techniques to obtain sensorineural hearing loss (SNHL) and conductive hearing loss (CHL) rates in school age children. Five mainstreamed public grade schools in northern Ethiopia were the sites for audiometry campaigns examining 1351 children and testing them with behavioral audiometry. Seven percent of students had SNHL > 20 dB in at least 1 frequency in at least 1 ear, and 0.6% of ears had SNHL > 50 dB. Eighteen percent8% of students had CHL > 20 dB in 1 or both ears. The frequency with the highest incidence of elevated pure tone thresholds was at 8000 Hz. Seven percent of students had an air bone gap at 2000 and/or 4000 Hz of at least 15 dB. Air bone gap is not obtained at 8000 Hz. There were 22 perforated tympanic membranes in 17 children (0.8% of tympanic membranes, 1% of students). This study gives a baseline for the prevalence of hearing loss in school age children in mainstreamed northern Ethiopian schools. It is the first of its kind and perhaps can help in estimated hearing health needs there. 2.

Temporal Coding of Single Auditory Nerve Fibers Is Not Degraded in Aging Gerbils.

People suffering from age-related hearing loss typically present with deficits in temporal processing tasks. Temporal processing deficits have also been shown in single-unit studies at the level of the auditory brainstem, midbrain, and cortex of aged animals. In this study, we explored whether temporal coding is already affected at the level of the input to the central auditory system. Single-unit auditory nerve fiber recordings were obtained from 41 Mongolian gerbils of either sex, divided between young, middle-aged, and old gerbils. Temporal coding quality was evaluated as vector strength in response to tones at best frequency, and by constructing shuffled and cross-stimulus autocorrelograms, and reverse correlations, from responses to 1 s noise bursts at 10-30 dB sensation level (dB above threshold). At comparable sensation levels, all measures showed that temporal coding was not altered in auditory nerve fibers of aging gerbils. Furthermore, both temporal fine structure and envelope coding remained unaffected. However, spontaneous rates were decreased in aging gerbils. Importantly, despite elevated pure tone thresholds, the frequency tuning of auditory nerve fibers was not affected. These results suggest that age-related temporal coding deficits arise more centrally, possibly due to a loss of auditory nerve fibers (or their peripheral synapses) but not due to qualitative changes in the responses of remaining auditory nerve fibers. The reduced spontaneous rate and elevated thresholds, but normal frequency tuning, of aged auditory nerve fibers can be explained by the well known reduction of endocochlear potential due to strial dysfunction in aged gerbils.SIGNIFICANCE STATEMENT As our society ages, age-related hearing deficits become ever more prevalent. Apart from decreased hearing sensitivity, elderly people often suffer from a reduced ability to communicate in daily settings, which is thought to be caused by known age-related deficits in auditory temporal processing. The current study demonstrated, using several different stimuli and analysis techniques, that these putative temporal processing deficits are not apparent in responses of single-unit auditory nerve fibers of quiet-aged gerbils. This suggests that age-related temporal processing deficits may develop more central to the auditory nerve, possibly due to a reduced population of active auditory nerve fibers, which will be of importance for the development of treatments for age-related hearing disorders.

Pure-tone thresholds and the binaural masking level difference

Although several studies have examined the relationship between high-frequency pure-tone thresholds and the 500-Hz binaural masking level difference (BMLD), the results have not always been consistent. In this study, a retrospective analysis was conducted on an existing dataset from over 3000 military service members that included both pure-tone thresholds measured as part of their annual hearing conservation testing and a 33-trial clinical test of the BMLD. There was only a slight dependence of the 500-Hz BMLD on high-frequency pure-tone thresholds. For listeners with elevated pure-tone thresholds, this dependence was in good agreement with the findings of Jerger et al. [Arch. Otolaryngol. 110, 290–296 (1984)] and slightly larger than that reported by Wilson and Weakley [J. Am. Acad. Audiol. 16, 367–382 (2005)]. For listeners with near-normal hearing, the dependence of the 500-Hz BMLD on the 4-kHz pure-tone threshold was substantially less than that reported by Bernstein and Trahiotis [J. Acoust. Soc. Am. 140, 3540–3548 (2016)]. A possible explanation might be the degree of training offered to the subjects and procedural differences between clinical and laboratory techniques. [The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government.]

Predicting speech reception thresholds of cochlear implant users using a modified envelope based measure

An envelope-correlation based measure (ECM), proposed in Yousefian and Loizou (2012), was applied to predict the speech reception thresholds (SRTs) of nine pre- and post-lingual cochlear implant (CI) users in the presence of speech-shaped masker and a female competing talker. A principal component analysis showed that CI users’ aided pure-tone thresholds were almost orthogonal to the predictions made by ECM, indicating that the ECM does not take aided hearing loss into account. A modified ECM is proposed which includes pure-tone thresholds into the predictions. The proposed model adjusts the ECM predictions based on the pure tone threshold values, and is able to predict CI users’ SRTs with higher correlation (r=0.92) compared to the original ECM (r=0.59). The results reported in this study indicate that information available on MAPs (e.g. T-levels, number of active electrodes) may not be sufficient to predict CI users’ SRTs in noise. In additions, results show that lack of audibility (i.e. elevated pure-tone thresholds) can dramatically limit speech intelligibility in noise in (even experienced) CI users.

Pure tone hearing profiles in children with otitis media with effusion

Introduction: Otitis media with effusion (OME) is a common middle ear disease in children. The associated conductive hearing loss is a major concern for hearing health professionals. The aim of the present study was to describe the configuration of pure tone audiograms of children with OME and to design a statistical stratification algorithm to facilitate hearing loss profiling in children with OME.Methods: School age children with OME were recruited. Bone and air conduction thresholds were obtained using standard procedures. Hierarchical cluster analysis was employed to determine audiometric profile groups. The Mandarin Hearing in Noise Test was used to measure sentence perception in children for cluster analysis validity assessment.Results: Ninety-seven children (164 ears) aged between 72 months and 153 months were examined. Air conduction thresholds averaged for 500 Hz, 1000 Hz and 2000 Hz were in the range of 8.3–53.3 dB HL with a mean of 26.8 dB HL. Bone conduction thresholds were found to be influenced by middle ear pathology with a maximal elevation at 2000 Hz of 25 dB HL. Four audiometric profiles were identified. Cluster 1 contained 54 ears (32.9%) with normal or near normal hearing, Clusters 2 contained 37 ears (22.6%) with mild hearing loss, Cluster 3 included 48 ears (29.3%) and Cluster 4 included 25 ears (15.2%) with moderate hearing loss. Stability and validity of the four-cluster profiling procedure was examined and established with satisfactory results.Conclusions: OME in children is associated with pure tone hearing thresholds ranging from normal to moderate hearing loss. The hierarchical clustering algorithm proved useful as a novel means of profiling hearing loss in children with OME and may assist in identifying affected children at greater risk of auditory disadvantage.Implications for rehabilitationA hierarchical cluster analysis method can be used to determine audiometric profiles in children with OME.This algorithm assists to identify children at greater risk of auditory disadvantage.Cluster groups with more elevated pure tone thresholds may be targeted for priority in clinical surveillance and medical/surgical intervention.

Fast frequency selectivity measures in listeners with severe hearing loss

Communication difficulties in severe hearing loss are a combination of elevated pure-tone thresholds and suprathreshold deficits; for example, frequency selectivity, which may be substantially impaired in listeners with severe loss. The purpose of this study was to investigate frequency selectivity measures in listeners with severe loss (pure-tone average 60–90 dB HL). Two tests were used: fast psychophysical tuning curves (PTC), in which an intermittent tone was detected during a narrowband noise masker swept continuously in frequency; and spectral ripple (SR), in which the number of sinusoidal ripples in the spectrum of a broadband noise was tracked in an adaptive forced-choice procedure. Results showed that both tests have advantages when evaluating listeners with severe loss. Fast PTC provided a direct representation of tuning in a specific frequency region but was limited by the residual dynamic range of the listener. Dynamic range limitations were partially overcome by combining data from multiple trials. SR was able to be performed by listeners with minimal dynamic range but the interpretation of results was limited by potential differences in hearing across the bandwidth of the stimuli. Both fast PTC and SR revealed information about suprathreshold deficits that could help guide audiological intervention. [Work supported by NIH.]

Nichtorganische (funktionelle) Hörstörungen bei Kindern

Nonorganic (functional) hearing loss in children is characterized by hearing loss without a detectable corresponding pathology in the auditory system. It is not an uncommon disease in childhood. Typically, there is a discrepancy between elevated pure tone thresholds and normal speech discrimination in everyday life. We evaluated 85 original publications, 27 reviews and 4 textbook articles. Mean age at diagnosis was 11.3 years. Girls were affected twice as often as boys. Patient histories showed a high prevalence of emotional and school problems. Pre-existing organic hearing loss can be worsened by nonorganic causes. A brainstem audiometry should confirm the diagnosis. The differential diagnosis includes auditory processing disorder, elevated thresholds in mental retardation and auditory neuropathy. We recommend taking a personal history including biographical factors, a psychological assessment including intelligence testing and referral to a child psychiatrist. Prognosis seems to be dependent on the severity of the patient's school and/or personal problems. Categorization following the Austen-Lynch model can be a valuable prognostic factor.

小児突発難聴の臨床像についての検討

Sudden sensorineural hearing loss is usually unilateral, and the cause is not identified in most adult cases. However, a specific cause has frequently been found in the case of children, in whom idiopathic sudden sensorineural hearing loss (ISHL) is comparatively rare. We investigated 20 cases of acute unilateral sensorineural hearing loss in children associated with a certain disease, but which was first diagnosed as ISHL. Thirteen patients aged 6 to 16 years old were diagnosed as having psychogenic (functional) hearing loss. Discrepancies in behavioral and objective tests are most valuable when functional hearing loss is suspected. Elevated pure-tone thresholds associated with normal distortion product otoacoustic emissions (DPOAEs) enable prompt further investigation. There are several conditions that may mimic functional hearing loss, so auditory brainstem response (ABR) testing is necessary to verify the actual cause. The unilateral profound hearing loss in 2 patients aged 7 and 11 years old was due to asymptomatic mumps proven by detecting the mumps IgM antibody. Total hearing recovery in the 125-1000 Hz frequencies occurred in one case. In 5 patients aged 6 to 12 years old with acute hearing loss and vertigo, high resolution CT imaging showed an abnormally enlarged vestibular aqueduct on the affected side. Large vestibular aqueduct syndrome should be considered in acute high-frequency sloping hearing loss with an A-B gap at low frequencies.

Progressive hearing loss after completion of cisplatin chemotherapy is common and more pronounced in children without spontaneous otoacoustic emissions before chemotherapy

Objective High frequency hearing loss following cisplatin chemotherapy is frequent in children and often necessitates the fitting of hearing aids. During therapy, hearing is usually monitored. Post-therapeutic follow-up does not routinely include monitoring of hearing, although there are indications that hearing thresholds can decline after therapy. Methods Pure-tone audiograms taken from 27 children (17 males, 10 females) treated with cisplatin at Muenster university hospital (mean age 9.84 years, standard deviation 3.67 years) including an audiological follow-up at least 6 months after therapy, were analyzed retrospectively. Results In follow-up tests after completion of therapy, 24.1% of all ears showed an increase in mean high frequency hearing thresholds (4–8 kHz). Post-therapeutic hearing deterioration was significant at 4 kHz and significantly more pronounced in children without measurable spontaneous otoacoustic emissions (SOAE) before therapy. Post-therapeutic hearing deterioration did not occur in ears with normal pure tone thresholds (≤10 dB at all frequencies) after cisplatin therapy. No correlation was found between post-therapeutic hearing deterioration and cranial irradiation. Conclusions Cisplatin chemotherapy follow-up should include audiological monitoring in all children with elevated pure tone thresholds after therapy. Routine SOAE measurements taken as part of baseline audiometry before the start of chemotherapy can be taken into consideration.

Secondhand Smoke and Sensorineural Hearing Loss in Adolescents

To investigate the hypothesis that second-hand smoke (SHS) exposure is associated with sensorineural hearing loss (SNHL) in adolescents. A complex, multistage, stratified geographic area design for collecting representative data from the noninstitutionalized US population. Cross-sectional data from National Health and Nutrition Examination Survey (2005-2006) were available for 1533 participants 12 to 19 years of age who underwent audiometric testing, had serum cotinine levels available, and were not actively smoking. SNHL was defined as an average pure-tone level greater than 15 dB for 0.5, 1, and 2 kHz (low frequency) and 3, 4, 6, and 8 kHz (high frequency). Secondhand smoke exposure, as assessed by serum cotinine levels, was associated with elevated pure-tone hearing thresholds at 2, 3, and 4 kHz, a higher rate of unilateral low-frequency SNHL (11.8% vs 7.5%; P < .04), and a 1.83-fold increased risk of unilateral low-frequency SNHL in multivariate analyses (95% confidence interval, 1.08-3.41). The prevalence of SNHL was directly related to level of SHS exposure as reflected by serum cotinine levels. In addition, nearly 82% of adolescents with SNHL did not recognize hearing difficulties. Secondhand smoke is associated with elevated pure-tone thresholds and an increased prevalence of low-frequency SNHL that is directly related to level of exposure, and most affected individuals are unaware of the hearing loss. Thus, adolescents exposed to SHS may need to be closely monitored for early hearing loss with periodic audiologic testing.

Different Manifestations of Auditory Neuropathy

Auditory neuropathy (AN) is characterized by a range of auditory deficits including elevated pure tone thresholds, reduced speech recognition scores, absence of auditory brainstem responses (ABR), and preservation of evoked otoacoustic emissions and the cochlear microphonic (CM) response. With increased advocacy for early implantation, patients with auditory neuropathy may be considered for implantation at or before one year of age. The decision for early implantation of very young patients with clinical test results that suggest AN should be made cautiously as a subset of patients presenting with the clinical constellation of AN may demonstrate reversible hearing loss over time.

Distortion product otoacoustic emissions in an industrial setting

Distortion product otoacoustic emissions (DPOAEs) is an objective sensitive test of cochlear function. The aim of this study was the evaluation of noise-induced hearing loss in a group of industrial workers, using this method in conjunction with standard puretone audiometry (PTA). One hundred and five subjects (210 ears) were included in the study. PTA, tympanometry, and DPOAEs were performed. Results were analyzed using a mixed analysis of variance model, and compared with the data of 34 normal persons of similar age and sex. We found statistically significant lower DPOAE levels in the noise-exposed group than in the control group. Additionally, the effect of frequency was significant, indicating that amplitude varied across frequency, with lower responses observed at 4 and 6 kHz, and maximum response found at 2 kHz. PTA showed a statistically significant effect of Group, owed to elevated puretone thresholds in the noise-exposed subjects, but a Frequency main effect was not found, although the interaction between Frequency and Group was statistically significant, as well as the interaction between Frequency and Ear. A main effect for Ear was found only in puretone thresholds, due to better thresholds in the left ears of the subjects, and not in DPOAE measurements. DPOAE levels were selectively affected at the higher frequencies, whereas puretone thresholds were affected at all frequencies. Direct comparison of the number of significantly affected ears between the two methods at 1, 2, and 4 kHz showed statistically significant differences at all comparisons, with more ears affected in PTA in comparison with DPOAEs at 4 kHz, whereas more ears were affected in DPOAEs at the lower frequencies (1 and 2 kHz). Therefore, it may be concluded that DPOAEs and PTA are both sensitive methods in detecting noise-induced hearing loss, with DPOAEs tending to be more sensitive at lower frequencies.

Age-related increase in auditory impairment in monkeys exposed in utero plus postnatally to methylmercury.

Hearing impairment and deafness have been reported as a result of developmental and adult exposure to methylmercury; however, objective assessment of auditory function is generally lacking. This study extends previous research in our laboratory in which monkeys exposed to methylmercury from birth to adulthood exhibited high-frequency hearing impairment. Monkeys (Macaca fascicularis) were exposed throughout gestation and postnatally until 4 years of age to 0, 10, 25, or 50 micrograms/kg/day mercury as methylmercuric chloride. When they were 11 and 19 years of age, pure-tone detection thresholds for six frequencies between 0.125 and 31.5 kHz were determined by means of a psychophysical (behavioral) procedure. At 19 years of age, all five methylmercury-exposed monkeys exhibited elevated pure-tone thresholds compared with controls. Impairment was generally observed across the full range of frequencies. Comparisons of performance at 11 and 19 years revealed relatively greater deterioration in function in treated compared with control monkeys. These results extend previously reported evidence of deficits in auditory function produced by postnatal methylmercury exposure, and describe a pattern of deficit across frequencies different than that observed in the previous study. This study also provides evidence for development or acceleration of impairment of auditory function during aging as a consequence of developmental methylmercury exposure.

Effects of lifetime lead exposure in monkeys on detection of pure tones.

Increased detection thresholds for pure tones were observed in a large cohort of children exposed to lead environmentally while smaller studies in lead-exposed workers have reported conflicting results on assessments of auditory function. Pure tone detection thresholds were determined in a group of monkeys (Macaca fascicularis) dosed with 2 mg/kg/day of lead from birth through testing at 13 years of age. Blood lead concentrations were stable at about 30 micrograms/dl until monkeys were 10-11 years of age at which time they increased to between 50 and 70 micrograms/dl. Five age- and rearing-matched monkeys served as controls. Detection thresholds were determined at six frequencies between 0.125 and 31.5 kHz. Ear phones were fit over both ears, and thresholds were determined for each ear separately. The monkey signaled detection of the tone by breaking contact with a stainless steel bar. Three lead-exposed monkeys exhibited normal pure tone detection functions. Three monkeys had thresholds outside of the control range at some frequencies; there was a tendency for higher frequencies to be differentially more affected. These findings are consistent with reports of elevated pure tone thresholds in humans exposed to lead developmentally, although the effect is smaller than might have been predicted given the concurrent blood lead concentrations of these monkeys.

Hearing loss in prison inmates.

The incidence of hearing disorders in 34 State Penitentiary prison inmates all with a previous history of drug abuse were investigated. Subjects were evaluated using routine pure-tone air conduction audiometry, immittance measures, and short-latency auditory brain stem responses. Of the 34 inmates, 20 (58.8%) demonstrated normal bilateral peripheral hearing sensitivity, whereas 10 (29.4%) inmates presented with some degree of hearing impairment. In addition, the conflicting results of elevated pure-tone thresholds with normal immittance measures and normal ABR findings suggested that four (11.8%) subjects exhibited functional hearing loss. The results of this study support the reported high incidence of hearing loss in the prison population. The synergistic effects of drug abuse, noise exposure, and head trauma as possible contributing factors are discussed.

Effects of hearing loss on utilization of short-duration spectral cues in stop consonant recognition.

The purpose of this experiment was to evaluate the utilization of short-term spectral cues for recognition of initial plosive consonants (/b,d,g/) by normal-hearing and by hearing-impaired listeners differing in audiometric configuration. Recognition scores were obtained for these consonants paired with three vowels (/a,i,u/) while systematically reducing the duration (300 to 10 ms) of the synthetic consonant-vowel syllables. Results from 10 normal-hearing and 15 hearing-impaired listeners suggest that audiometric configuration interacts in a complex manner with the identification of short-duration stimuli. For consonants paired with the vowels /a/ and /u/, performance deteriorated as the slope of the audiometric configuration increased. The one exception to this result was a subject who had significantly elevated pure-tone thresholds relative to the other hearing-impaired subjects. Despite the changes in the shape of the onset spectral cues imposed by hearing loss, with increasing duration, consonant recognition in the /a/ and /u/ context for most hearing-impaired subjects eventually approached that of the normal-hearing listeners. In contrast, scores for consonants paired with /i/ were poor for a majority of hearing-impaired listeners for stimuli of all durations.

Bitemporal lesions dissociate auditory evoked potentials and perception

We studied auditory evoked potentials (AEPs) in an 82-year-old female patient who became suddenly deaf following the second of two strokes. The patient showed markedly elevated pure tone thresholds, was unable to discriminate sounds and could not understand speech. Brain-stem auditory evoked potentials (BAEPs) were normal. CT scans revealed bilateral lesions of the superior temporal plane which included auditory cortex. Two experiments were performed. In the first, tones, complex sounds and speech stimuli were presented at intensities above and below the patient's perceptual threshold. P1, N1 and P2 components were elicited by each of the stimuli — whether or not they were perceived. In particular, stimuli presented below threshold evoked large amplitude, short latency responses comparable to those produced in a control subject. In a second experiment, the refractory properties of the N1-P2 were examined using trains of tones. They were also found to be similar to those of normal subjects. Shifts in the pitch of the tones near the end of the train (when refractory effects were maximal) evoked N1-P2s with enhanced amplitudes, although the change in pitch was not perceived by the patient. In both experiments AEP scalp topographies were normal. The results suggest that bitemporal lesions of auditory cortex can dissociate auditory perception and long-latency auditory evoked potentials. A review of evoked potential studies of cortical deafness suggests that the neural circuits responsible for N1-P2 generation lie in close proximity to those necessary for auditory perception.

Frequency resolution and discrimination of constant and dynamic tones in normal and hearing-impaired listeners.

Frequency resolution and three tasks of frequency discrimination were measured at 500 and 4000 Hz in 12 normal and 12 hearing-impaired listeners. A three-interval, two-alternative forced-choice procedure was used. Frequency resolution was measured with an abbreviated psychoacoustical tuning curve. Frequency discrimination was measured for (1) a fixed-frequency standard and target, (2) a fixed-frequency standard and a frequency-transition target, and (3) frequency-transition standard and a frequency-transition target. The 50-ms frequency transitions had the same final frequency as the standards, but the initial frequency was lowered to obtain about 79% discrimination performance. There was a strong relationship between poor frequency resolution and elevated pure-tone thresholds, but only a very weak relationship between poor frequency discrimination and elevated pure-tone thresholds. Several hearing-impaired listeners had normal discrimination performance together with pure-tone thresholds of 80-90 dB HL. A slight correlation was found between word recognition and frequency discrimination, but a detailed comparison of the phonetic errors and either the frequency-discrimination or frequency-resolution tasks failed to suggest any consistent interdependencies. These results are consistent with previous work that has suggested that frequency resolution and frequency discrimination are independent processes.