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PubMed2002

Quality rating test of hearing aid benefit in the NIDCD/VA Clinical Trial.

OBJECTIVE: As part of a large clinical trial that compared three hearing aid circuits using several evaluation methods, judgments about quality of listening experiences were sought from all subjects. Three dimensions were examined: loudness, noise interference and overall liking (quality). DESIGN: Eight Audiology units in VA Medical Centers participated. Three hearing aid circuits were compared: linear peak clipper, compression limiter, and wide dynamic range compressor. The experimental design was a three-period, three-treatment crossover design. Baseline measures were made using a battery of tests in unaided conditions. Subjects (N = 360) were then stratified by participating site and randomized to one of six sequences of the three hearing aid circuits. Each circuit was fit binaurally and all subjects used each of the three circuits for 3 mo. All outcome measures were administered in unaided and aided conditions after each 3-mo period. The study used a double-blind strategy, i.e., neither the audiologist giving the tests nor the subject knew which circuit was being used. A different audiologist programmed the devices. RESULTS: For loudness judgments, soft and loud presentations of speech in quiet and in babble competition were judged more comfortable via the wide dynamic range circuit. The noise interference tasks and overall liking of the listening experience showed few significant differences across circuits. All circuits made the listening experience more comfortably loud for soft and conversation-level speech. CONCLUSIONS: Differences across circuits in terms of the overall quality of the listening experience and how noise interference was rated were small. Only isolated conditions, usually favoring the WDRC circuit, reached significance levels. The loudness dimension results were clearer. The WDRC circuit made sounds at either the loud or soft extreme more comfortable. When subjects were grouped by amount and configuration of hearing loss, the advantages for the WDRC and to a lesser extent the linear compression-limited circuit were clearest among subjects with mild hearing losses with a >10 dB/octave high-frequency drop, and those with moderate, relatively flat hearing losses.

Aged↗
PubMed2004

Output levels of commercially available portable compact disc players and the potential risk to hearing.

OBJECTIVE: To measure the sound levels generated by the headphones of commercially available portable compact disc players and provide hearing healthcare providers with safety guidelines based on a theoretical noise dose model. DESIGN: Using a Knowles Electronics Manikin for Acoustical Research and a personal computer, output levels across volume control settings were recorded from headphones driven by a standard signal (white noise) and compared with output levels from music samples of eight different genres. Many commercially available models from different manufacturers were investigated. Several different styles of headphones (insert, supra-aural, vertical, and circumaural) were used to determine if style of headphone influenced output level. RESULTS: Free-field equivalent sound pressure levels measured at maximum volume control setting ranged from 91 dBA to 121 dBA. Output levels varied across manufacturers and style of headphone, although generally the smaller the headphone, the higher the sound level for a given volume control setting. Specifically, in one manufacturer, insert earphones increased output level 7-9 dB, relative to the output from stock headphones included in the purchase of the CD player. In a few headphone-CD player combinations, peak sound pressure levels exceeded 130 dB SPL. CONCLUSIONS: Based on measured sound pressure levels across systems and the noise dose model recommended by National Institute for Occupational Safety and Health for protecting the occupational worker, a maximum permissible noise dose would typically be reached within 1 hr of listening with the volume control set to 70% of maximum gain using supra-aural headphones. Using headphones that resulted in boosting the output level (e.g., insert earphones used in this study) would significantly decrease the maximum safe volume control setting; this effect was unpredictable from one manufacturer to another. In the interest of providing a straightforward recommendation that should protect the hearing of the majority of consumers, reasonable guidelines would include a recommendation to limit headphone use to 1 hr or less per day if using supra-aural style headphones at a gain control setting of 60% of maximum.

Acoustic Stimulation↗
PubMed1998

Optimization of speech processor fitting strategies for Chinese-speaking cochlear implantees.

OBJECTIVES: To compare speech recognition performance in Chinese-speaking cochlear implant patients with a speech processor program selected by the clinical audiologist in Taiwan and with a new speech processor program based on the Washington University clinical procedure developed by Skinner et al. STUDY DESIGN: Six adult Chinese-speaking patients implanted with the Nucleus cochlear implant system participated in this study. METHODS: A fitting procedure developed in 1995 by Skinner et al. at Washington University School of Medicine was used to create a new speech processor program to optimize each patient's hearing in everyday life. Speech tests (vowels, consonants, tones, and words), sound-field thresholds, and a self-report questionnaire were used to evaluate each patient's performance with his or her previous speech processor program and a new one. RESULTS: Four of the six patients had significant changes from the previous to the new speech processor program. These changes were associated with improvement in score on at least one speech test, more sensitive sound field thresholds, and reported improvement in some everyday listening situations on the questionnaire. CONCLUSIONS: These results suggest that use of this procedure with adult cochlear implantees may improve benefit in everyday life. Analysis of the speech test stimuli and patients' responses provides a basis for modification or creation of new Mandarin Chinese speech tests for preoperative and postoperative evaluation of adult cochlear implant patients.

Adolescent↗
PubMed2003

Hearing impairment and tinnitus pitch in patients with unilateral tinnitus: comparison of sudden hearing loss and chronic tinnitus.

OBJECTIVES: The objectives were to analyze the results of pitch-matching and loudness-balance testing in patients with unilateral tinnitus and to evaluate the relationship between audiological findings based on the tinnitus-affected and tinnitus-unaffected threshold differences and tinnitus pitch by using linear interpolation methods. In addition, the effects of the duration of the tinnitus on this relationship were investigated. Sudden sensorineural hearing loss with tinnitus was selected for the "acute tinnitus" group, and unilateral tinnitus with unknown disease and a duration of more than 3 months was selected for the "chronic tinnitus" group. STUDY DESIGN: Retrospective study of the clinical records of patients. METHODS: One hundred thirty-two patients with unilateral tinnitus (comprising 68 female [51.5%] and 64 male [48.5%] patients) were investigated as subjects. Their mean age was 50.4 years (SD = 15.8 y). All patients underwent otoneurological testing, including the pure-tone audiogram and pitch-matching and loudness-balance tests. RESULTS: The mean difference in the hearing threshold between the tinnitus-affected ear and the tinnitus-unaffected ear was largest near the tinnitus pitch in both the acute and the chronic tinnitus groups. However, the relationship between hearing impairments and tinnitus pitch was somewhat different in the two groups: It exhibited a single smooth peak in the acute tinnitus group but a bimodal peak in the chronic tinnitus group. CONCLUSION: The results suggest that tinnitus is related to hearing impairment in the same frequency region in patients with sudden sensorineural hearing loss with tinnitus or in patients with chronic tinnitus, whereas some instances of chronic tinnitus are caused by reorganization in cortical cells.

Acute Disease↗
PubMed2002

Transmeatal low-power laser irradiation for tinnitus.

OBJECTIVE: To evaluate effectiveness of 60-mW laser irradiation in the treatment of tinnitus. STUDY DESIGN: Prospective, randomized double-blind study. METHODS: This investigation included 68 ears in 45 patients with disabling unilateral or bilateral tinnitus. The active or placebo laser treatment was administered transmeatally once a week for 6 minutes. Laser irradiation was performed four times during a 4-week period. A questionnaire was administered to evaluate the loudness, duration, quality, and annoyance of tinnitus before and after irradiation. The loudness and pitch match for tinnitus were obtained, and distortion product otoacoustic emissions were also examined. RESULTS: No significant difference was observed between the active and placebo laser groups with regard to outcome of loudness, duration, quality, and annoyance of tinnitus. In one patient who received active laser treatment, acute hearing deterioration occurred after the third irradiation. CONCLUSION: Transmeatal low-power laser irradiation with 60 mW is not effective for the treatment of tinnitus.

Adult↗
PubMed2003

Coding of sounds in the auditory system and its relevance to signal processing and coding in cochlear implants.

OBJECTIVE: To review how the properties of sounds are "coded" in the normal auditory system and to discuss the extent to which cochlear implants can and do represent these codes. DATA SOURCES: Data are taken from published studies of the response of the cochlea and auditory nerve to simple and complex stimuli, in both the normal and the electrically stimulated ear. REVIEW CONTENT: The review describes: 1) the coding in the normal auditory system of overall level (which partly determines perceived loudness), spectral shape (which partly determines perceived timbre and the identity of speech sounds), periodicity (which partly determines pitch), and sound location; 2) the role of the active mechanism in the cochlea, and particularly the fast-acting compression associated with that mechanism; 3) the neural response patterns evoked by cochlear implants; and 4) how the response patterns evoked by implants differ from those observed in the normal auditory system in response to sound. A series of specific issues is then discussed, including: 1) how to compensate for the loss of cochlear compression; 2) the effective number of independent channels in a normal ear and in cochlear implantees; 3) the importance of independence of responses across neurons; 4) the stochastic nature of normal neural responses; 5) the possible role of across-channel coincidence detection; and 6) potential benefits of binaural implantation. CONCLUSIONS: Current cochlear implants do not adequately reproduce several aspects of the neural coding of sound in the normal auditory system. Improved electrode arrays and coding systems may lead to improved coding and, it is hoped, to better performance.

Cochlea↗
PubMed2003

Audiologic manifestations of patients with post-treatment Lyme disease syndrome.

OBJECTIVE: The purpose of this study was to characterize auditory function in patients diagnosed with post-treatment Lyme disease syndrome (PTLDS). DESIGN: Eighteen patients with PTLDS were evaluated and compared to a normal population. Evaluations consisted of pure tone and speech thresholds, word recognition (WRS), acoustic immittance battery, auditory brain stem response (ABR), and loudness discomfort level (LDL). Both seropositive and seronegative patients were evaluated. Audiologists were blinded to patient status. RESULTS: Forty four percent of the patients had one or more abnormal pure tone thresholds compared to gender- and age-adjusted norms. Thirty-one percent showed abnormally reduced LDLs, and 17% had abnormal acoustic reflexes at one or more frequencies. CONCLUSIONS: This paper catalogs previously unstudied long-term auditory system sequelae resulting from PTLDS. Our most significant finding was the dramatically reduced loudness tolerance in the presence of either normal or minimally impaired hearing. The clinician is encouraged to consider PTLDS when confronted with these or similar findings in patients having history of Borrelia burgdorferi infection and continued complaints.

Adult↗
PubMed2004

Is normal or less than normal overall loudness preferred by first-time hearing aid users?

OBJECTIVE: Most prescriptive methods for nonlinear, wide dynamic range compression (WDRC) hearing aids are based on the assumption that a hearing-impaired listener should perceive amplified sounds at the same overall loudness as would a normal-hearing listener without amplification. However, some previous research on linear amplification has indicated that subjects prefer less overall gain than prescribed by the most commonly used prescriptive method for linear hearing aids, NAL-R, a method that gives close to normal overall loudness for a mid-level input. The current study aims at comparing two prescriptive methods for WDRC hearing aids. The methods differ in the overall loudness they aim to give the hearing aid user. One method, called NormLoudn, is based on a generic method that prescribes gain so that the overall loudness is restored to normal. Another method, called LessLoudn, is based on a hearing aid specific prescription, and gives the hearing aid user less than normal overall loudness. Do first-time hearing aid users prefer the method that restores overall loudness to normal or the method that gives less than normal overall loudness? DESIGN: Twenty-one first-time hearing aid users with typical hearing losses for this group of clients participated in a crossover blinded field study where the two fitting methods were compared using a multi-programmable hearing aid, Danalogic 163D. Preference in the field was evaluated using interview, questionnaire, and diary. The field test was accompanied by laboratory tests, which included paired comparison judgments of preference and loudness and a speech recognition test. Loudness calculations were also used when interpreting the results, and a theoretical comparison with other prescriptive methods for WDRC hearing aids was made. RESULTS: After necessary adjustments, the measured gain for the two methods was similar in gain-frequency shape, but NormLoudn gave more overall gain than LessLoudn. Generally, NormLoudn fittings led to calculated overall loudness that was close to normal, whereas LessLoudn fittings, in median, led to 3-7 phon less than normal calculated overall loudness according to the loudness model used. During the interview performed after the field test, 19 out of the 21 subjects stated that they preferred LessLoudn. Also the questionnaire and the diary showed a clear preference for LessLoudn in all types of listening situations. Paired comparisons of preference in the laboratory supported the findings in the field. LessLoudn was preferred to NormLoudn in all tested situations, except for soft speech in very soft noise where there was no significant preference for either method. Speech recognition scores were similar for the two fittings. The difference in calculated loudness was clearly distinguishable to the subjects and seemed to govern their preferences. CONCLUSIONS: LessLoudn, which gave less than normal overall loudness according to the loudness model used, was preferred both in the field and in the laboratory tests. Speech recognition scores were similar for both methods. A comparison between the measured gain for NormLoudn and the gain prescribed by CAMEQ, NAL-NL1, and DSL[i/o], suggests that all three prescriptive procedures (DSL[i/o] in particular) would probably overestimate the required gain for subjects without hearing aid experience and with mild to moderate hearing loss. When providing these clients with hearing aids, it seems important to include a careful adjustment of the overall gain to avoid overamplification if the prescription used aims at restoring overall loudness to normal according to the loudness model used here.

Aged↗
PubMed2006

Reaction time to 1- and 4-kHz tones as a function of sensation level in listeners with normal hearing.

OBJECTIVE: Measures of reaction time (RT) near threshold have been used to indicate whether listeners with hearing losses of primarily cochlear origin experience greater loudness at elevated thresholds than at normal thresholds. These measurements have been based on the assumption that RTs near threshold are not affected by stimulus frequency in the 1- to 4-kHz range. The present study tests this hypothesis. DESIGN: To gain an understanding of how RT is affected by frequency, RTs to 1- and 4-kHz tones were measured in 16 listeners with normal hearing across a wide range of sensation levels (SLs). RESULTS: Statistical analyses indicate that RTs are affected by frequency in some listeners. This effect is most common at low SLs but is also present at higher SLs. Learning effects could not account for the observed differences between RTs at the two frequencies. CONCLUSIONS: Although reaction time-especially at low levels-is affected by stimulus frequency in some listeners, the effect is not large enough to account for the differences in RTs measured in all listeners with impaired hearing in other studies.

Acoustic Stimulation↗
PubMed2006

Experimental evaluation of different methods of limiting the maximum output of hearing aids.

OBJECTIVE: A series of experiments designed to test the preferences of people with moderate to profound hearing losses for limiting the output of hearing aids by using peak clipping (PC), fast compression limiting (FCL), PC and FCL, and these three methods in combination with slow compression limiting (SCL) was conducted. DESIGN: Nineteen participants with moderate to profound sensorineural or mixed losses were recruited. In the first experiment, preferences for either PC or FCL were tested in a field trial in the participants' usual environments.A second experiment examined the acceptance of PC, FCL, and FCL + PC, using paired comparisons in a laboratory setting. The third experiment involved further paired comparisons in the laboratory to evaluate whether participants preferred PC, FCL, PC and FCL combined, or the three methods when combined with SCL. RESULTS: The participants showed no statistically significant preferences for either peak clipping or fast compression limiting in the field trial. In the laboratory trial, both FCL + PC and FCL were significantly preferred over PC alone, and the addition of FCL to PC was most advantageous to participants who required the lowest maximum limiting output. The most dramatic laboratory result was the convincing preference in paired comparison testing of combining SCL with PC and/or FCL. CONCLUSIONS: Slow compression limiting appears to be a desirable feature in hearing aids for clients with a moderate to profound hearing loss. Preferences were not as pronounced when peak clipping, fast compression limiting, and peak clipping plus fast compression limiting were compared, but participants favored the condition that had the least amount of peak clipping.

Adult↗
PubMed2006

Conditioning pulse trains in cochlear implants: effects on loudness growth.

HYPOTHESIS: The addition of a high-rate (5 kpps) conditioning pulse train to the input signal of cochlear implants will result in shallower loudness growth across the dynamic range of cochlear implant patients. BACKGROUND: High-rate conditioning pulse trains have been shown to increase the dynamic range of sinusoidal stimuli for cochlear implant recipients in a manner consistent with stochastic resonance. This study further characterizes the effects of conditioning stimuli on loudness by examining the loudness growth functions for sinusoidal stimuli both with and without conditioning. METHODS: Seven post-lingually deafened adults using the Clarion CII cochlear implant participated in this study. The loudness growth functions of each subject were characterized using sinusoidal stimuli, both with and without the presence of a high-rate conditioner. Loudness was measured using magnitude estimation. RESULTS: The loudness growth functions of all seven subjects demonstrate an increase in dynamic range for sinusoidal stimuli with the addition of the conditioning pulse train. Shallower loudness growth is seen across the dynamic range with the addition of a conditioner. This result was shown for loudness growth fitted to exponential, power, and cumulative gaussian functions. CONCLUSION: The addition of high-rate conditioning pulse trains to sinusoidal stimuli presented to cochlear implant recipients results in larger dynamic ranges, with more gradual increases in loudness growth across the dynamic range. This suggests that signal-processing strategies incorporating conditioning may be clinically useful, requiring less compression of the input signal and leading to less distortion perceived by cochlear implant patients.

Adult↗
PubMed2006

Effect of gabapentin on the sensation and impact of tinnitus.

OBJECTIVES/HYPOTHESIS: This study evaluated the effectiveness of gabapentin in treating chronic tinnitus in two populations: participants with tinnitus with associated acoustic trauma and participants with tinnitus without associated acoustic trauma. The hypothesis was that gabapentin would decrease both subjective and objective features of tinnitus in the trauma group but would be less effective in the nontrauma group. STUDY DESIGN: Prospective, placebo-controlled, single-blind clinical trial. METHODS: Pure-tone audiograms and personal histories were used to categorize tinnitus etiology as either secondary to acoustic trauma or not associated with acoustic trauma. Participants were restricted to those with moderate to severe tinnitus for at least 1 year. All participants received gabapentin in a graduated ascending-descending dose series extending over 20 weeks (peak dose of 2,400 mg/d). RESULTS: There was a significant improvement in tinnitus annoyance for the trauma group (P = .05). Other subjective aspects of tinnitus were not significantly affected in either group. Between-subject variability of therapeutic response was considerable. Nevertheless, in consideration of subjective loudness ratings, 4 of 19 nontrauma participants and 6 of 20 trauma participants showed an improvement of 20% or better. In consideration of psychoacoustic loudness estimates, 3 of 19 nontrauma and 6 of 20 trauma participants showed an improvement of 20 dB HL or greater. Evenly dividing each group into high and low responders revealed significant improvement in loudness at 1,800 and 2,400 mg/day for the trauma high-response subgroup (P = .007). No significant improvement was obtained for other subgroups. CONCLUSION: Gabapentin is effective in reducing subjective and objective aspects of tinnitus in some individuals, with the best therapeutic response obtained in individuals with associated acoustic trauma.

Adolescent↗
PubMed2005

Effects of the critical band on auditory-evoked magnetic fields.

Changes in the bandwidth affect the perceived loudness of a stimulus even when the level of the stimulus remains fixed. If the bandwidth of a sound is varied while maintaining the overall intensity, the loudness remains constant as long as the bandwidth is less than the critical bandwidth. If the bandwidth is increased beyond the critical bandwidth, the loudness increases with increasing bandwidth. Human cortical responses as a function of stimulus bandwidth were examined by recording auditory-evoked magnetic fields. The results showed that the N1m magnitudes, that is, the estimated equivalent current dipole moments, increased with increasing bandwidth when the bandwidth was increased beyond the critical bandwidth.

Acoustic Stimulation↗
PubMed2006

Constraints on decay of environmental sound memory in adult rats.

When adult rats are pretreated with a 48-h-long 'repetitive nonreinforced sound exposure', performance in two-sound discriminative operant conditioning transiently improves. We have already proven that this 'sound exposure-enhanced discrimination' is dependent upon enhancement of the perceptual capacity of the auditory cortex. This study investigated principles governing decay of sound exposure-enhanced discrimination decay. Sound exposure-enhanced discrimination disappeared within approximately 72 h if animals were deprived of environmental sounds after sound exposure, and that shortened to less than approximately 60 h if they were exposed to environmental sounds in the animal room. Sound-deprivation itself exerted no clear effects. These findings suggest that the memory of a passively exposed behaviorally irrelevant sound signal does not merely pass along the intrinsic lifetime but also gets deteriorated by other incoming signals.

Acoustic Stimulation↗
PubMed1995

Time estimation deficits in developmental dyslexia: evidence of cerebellar involvement.

In addition to their language-related difficulties, dyslexic children suffer problems in motor skill, balance, automatization and speeded performance. Given the recent evidence for cerebellar involvement in the acquisition of language fluency, these problems suggest cerebellar deficit. To test the hypothesis of cerebellar dysfunction in dyslexia, a time estimation task considered to be a sensitive index of cerebellar function was administered to matched groups of dyslexic and control children. The dyslexic children showed the predicted deficit on time estimation (among the most severe obtained in our research programme) but not on a control, loudness estimation, task. Cerebellar dysfunction, therefore, provides a parsimonious account of otherwise disparate data on deficits in dyslexia.

Acoustic Stimulation↗
PubMed2002

Auditory memory for backward masking signals in children with language impairment.

This study was designed to investigate early auditory memory and its possible contribution to an auditory processing deficit shown by some children with language impairment. Ten children with language impairment and 10 age-matched controls participated in a series of simultaneous and backward masking tasks. The same backward masking stimulus was then used to elicit a mismatch negativity response. In the behavioral conditions, children in the language impairment group had significantly higher (poorer) signal thresholds than their nonimpaired controls in backward masking, but their thresholds in simultaneous masking were not significantly different. In the mismatch-negativity conditions, latency was prolonged and the amplitude was diminished in the children with language impairment. Taken together, these psychoacoustic and electrophysiological data suggest that in a group of children with language impairment, underlying the nonsensory language disorder, there is a neurophysiological impairment in auditory memory for complex, nonlinguistic sounds.

Attention↗
PubMed1979

Temporary threshold shift, loudness, and auditory evoked potentials.

TTS2 of 20dB was produced in a group of subjects using a 1000 Hz pure tone. All TTS and related measurements were made at 1500 Hz. The recovery of TTS, and of TLS or 'temporary loudness shift' (measured against a reference tone at 20db, 40dB and 60dB SL in the opposite ear), as well as N1-P2 amplitude of the Vertex potential, were plotted. There was an orderly recovery of both TLS and TTS although the rate of recovery of the latter was noticeably more rapid. Recovery of N1-P2 amplitude was much less orderly, although it did recover in much the same way. When the amplitudes were measured at 40dB SL the recovery was more orderly and followed the course of TTS more closely. It was concluded that any relation between N1-P2 amplitude and growth of loudness was indirect.

Acoustic Stimulation↗
PubMed1990

Electrical stimulation of the round window: a selection procedure for single-channel cochlear implantation.

Many suggestions have been made as to the most appropriate tests for the selection of patients for cochlear implantation. One of the most appropriate tests when selecting patients for a round window extracochlear device is stimulation of the round window itself by a temporary electrode of the same size. Fourteen patients have been tested, 7 of whom were judged to have a good response to electrical stimulation. Six patients have gone on to permanent implantation with a round window cochlear implant.

Acoustic Impedance Tests↗