Can real-ear insertion gain deviations from generic fitting prescriptions predict self-reported outcomes?

OBJECTIVE: The aim of this study was to determine whether the differences in insertion gains from the first fit to generic prescriptions of hearing aids can predict the self-reported hearing aid (HA) outcomes for first-time and experienced HA users. DESIGN: This was a prospective observational study. STUDY SAMPLE: The study included 885 first-time and 330 experienced HA users with a valid real-ear measurement on both ears and answers to the abbreviated version of the Speech, Spatial, and Quality of Hearing (SSQ12) and the International Outcome Inventory for Hearing Aids (IOI-HA) questionnaires. RESULTS: K-means clustering of gain differences between individual real-ear insertion gain to three generic gain prescriptions (NAL-NL2, NAL-RP, and one-third gain rules) was performed. The gain difference at higher frequencies generally differentiated the clusters. The experienced users in the cluster with fittings closest to NAL-NL2 and NAL-RP prescription were found to exhibit a higher IOI-HA Factor 1 score (representing the overall benefit of the hearing aid use). The gain differences to generic prescription did not affect other self-reported outcomes for first-time and experienced HA users. CONCLUSION: The experienced HA users with minimal gain deviations from generic prescriptions reported better self-perceived benefits than users with larger deviations. However, this was not apparent in first-time users.

The effect of hearing aid treatment on health-related quality of life in older adults with hearing loss.

OBJECTIVE: To investigate the effect of hearing aid (HA) intervention on long-term health-related quality of life (HRQoL) changes in first-time and experienced HA users using the 15D questionnaire. Secondly, the study explored the relationship between clinical parameters and changes in 15D scores. DESIGN: A prospective observational study. STUDY SAMPLE: The study population included 1562 patients (1113 first-time and 449 experienced HA users) referred for HA rehabilitation. All patients responded to the 15D at baseline, two months after HA fitting, and at long-term follow-up (698 ± 298 d). RESULTS: Among both first-time and experienced HA users, significant improvements in hearing-dimension (15D-3) score were observed at two-month follow-up which sustained at long-term follow-up. 15D total scores significantly decreased at long-term follow-up. Self-reported hearing abilities, word recognition scores, and HA use time were significantly and positively correlated to increased 15D. CONCLUSIONS: Both groups of HA users reported improved hearing-related QoL after HA treatment which sustained at long-term follow-up but the improvement in total 15D total score did not sustain for either group. The results suggest that HA intervention positively affects hearing-related QoL among older adults with hearing loss, and the findings support the use of 15D as a tool for the evaluation of HA treatment effects.

Difference in SII provided by initial fit and NAL-NL2 and its relation to self-reported hearing aid outcomes.

OBJECTIVE: The speech intelligibility index (SII) is used to quantify the audibility of the speech. This study examined the relationship between self-reported hearing aid (HA) outcomes and the difference in aided SII (SIIA) calculated from the initial fit (IF) gain and that prescribed as per the second generation of National Acoustic Laboratory Non-Linear (NAL-NL2). DESIGN: A prospective observational study. STUDY SAMPLE: The study included 718 first-time and 253 experienced HA users. All users had a valid real-ear measurement (REM) at three input levels (55, 65 and 80 dB SPL). RESULTS: The gain provided by IF was lower than NAL-NL2 at 55 and 65 dB SPL. IF gain exhibited reduced compression than NAL-NL2 as input levels increased from 55 to 80 dB SPL. On average, the SIIA provided by IF was significantly lower than that for NAL-NL2 at all input levels. The difference in SIIA between IF and NAL-NL2 at 80 dB SPL input level with 0 dB signal-to-noise ratio (SNR) turned out to be a predictor for self-reported outcome for first-time HA users. CONCLUSION: The study suggests that an SIIA close to that provided by NAL-NL2 at high input levels would be preferred to obtain a better self-reported outcome. .

A history of occupational noise exposure is associated with steep-slope audiograms and poorer self-reported hearing-aid outcomes.

OBJECTIVE: To investigate the effects of previous occupational noise exposure in older adults with hearing loss on (1) audiometric configuration and acoustic reflex (AR) thresholds and (2) self-reported hearing abilities and hearing aid (HA) effectiveness. DESIGN: A prospective observational study. STUDY SAMPLE: The study included 1176 adults (≥60 years) with bilateral sensorineural hearing loss. Pure-tone audiometry, AR thresholds, and responses to the abbreviated version of the Speech, Spatial, and Qualities of Hearing Scale (SSQ12) and the International Outcome Inventory for Hearing Aids (IOI-HA) questionnaire were obtained, along with information about previous occupational noise exposure. RESULTS: Greater occupational noise exposure was associated with a higher prevalence of steeply sloping audiograms in men and women and a 0.32 (95% CI: -0.57; -0.06) scale points lower mean SSQ12 total score among noise-exposed men. AR thresholds did not show a significant relation to noise-exposure status, but hearing thresholds at a given frequency were related to elevated AR thresholds at the same frequency. CONCLUSIONS: A noise exposure history is linked to steeper audiograms in older adults with hearing loss as well as to poorer self-reported hearing abilities in noise-exposed men. More attention to older adults with previous noise exposure is warranted in hearing rehabilitation.

Stimulus ratio dependence of low-frequency distortion-product otoacoustic emissions in humans.

Active amplifiers within the cochlea generate, as a by-product of their function, distortion-product otoacoustic emissions (DPOAEs) in response to specific two-tone stimuli. Focus has been on invoking emissions in a mid-frequency range from ∼0.5 to 4 kHz. The present study investigates stimulus parameters of the DPOAE at 2f1-f2 frequencies below 0.5 kHz. Eighteen out of 21 young human adults screened had audiometrically normal hearing for inclusion in the experiment. DPOAEs were measured with pure-tone stimuli in four configurations: f2 fixed around 2.13 kHz, f2 fixed around 0.53 kHz, 2f1-f2 fixed at 1.23 kHz and 0.25 kHz. Eight stimulus ratios, f2/f1, and three stimulus sound pressure levels, L1/L2, were measured in each configuration. Trends in ratio-magnitude responses for the mid-frequency DPOAE agree with those reported in previous literature. DPOAEs are not limited to distortion frequencies >0.5 kHz, but the stimulus ratio invoking the largest DPOAE in the mid-frequency range does not do so in the low-frequency range. Guiding the ratio according to the equivalent rectangular bandwidth of auditory filters maintains the DPOAE level.

Auditory Profile-Based Hearing Aid Fitting: Self-Reported Benefit for First-Time Hearing Aid Users.

Background: Although hearing aids (HAs) can compensate for reduced audibility, functional outcomes and benefits vary widely across individuals. As part of the Danish 'Better hEAring Rehabilitation' (BEAR) project, four distinct auditory profiles differing in terms of audiometric thresholds and supra-threshold hearing abilities were recently identified. Additionally, profile-specific HA-fitting strategies were proposed. The aim of the current study was to evaluate the self-reported benefit of these profile-based HA fittings in a group of new HA users. Methods: A total of 205 hearing-impaired older adults were recruited from two Danish university hospitals. Participants were randomly allocated to one of two treatment groups: (1) NAL-NL2 gain prescription combined with default advanced feature settings ('reference fitting') or (2) auditory profile-based fitting with tailored gain prescription and advanced feature settings ('BEAR fitting'). Two months after treatment, the participants completed the benefit version of the short form of the Speech, Spatial, and Qualities of Hearing Scale (SSQ12-B) and the International Outcome Inventory for Hearing Aids (IOI-HA) questionnaire. Results: Overall, participants reported a clear benefit from HA treatment. However, no significant differences in the SSQ12-B or IOI-HA scores between the reference and BEAR fittings were found. Conclusion: First-time users experience clear benefits from HA treatment. Auditory profile-based HA fitting warrants further investigation.

Self-Reported Hearing-Aid Use Patterns in an Adult Danish Population.

The retrospective reporting of users' hearing aid (HA) usage can provide insight into individualized HA usage patterns. Understanding these HA usage patterns can help to provide a tailored solution to meet the usage needs of HA users. This study aims to understand the HA usage pattern in daily-life situations from self-reported data and to examine its relationship to self-reported outcomes. A total of 1537 participants who responded to questions related to situations where they always took off or put on the HAs were included in the study. A latent class analysis was performed to stratify the HA users according to their HA usage pattern. The results showed distinct usage patterns in the latent classes derived for both scenarios. The demographics, socio-economic indicators, hearing loss, and user-related factors were found to impact HA usage. The results showed that the HA users who reported using the HAs all the time (regular users) had better self-reported HA outcomes than situational users, situational non-users, and non-users. The study explained the underlying distinct HA usage pattern from self-reported questionnaires using latent class analysis. The results emphasized the importance of regular use of HAs for a better self-reported HA outcome.

Value Propositions of Public Adult Hearing Rehabilitation in Denmark.

Objective: To obtain and evaluate detailed descriptions of potential value propositions as seen by adults undergoing hearing rehabilitation with hearing aids. Design: Semi-structured interviews with patients and audiologists, a literature search, and the inclusion of domain knowledge from experts and scientists were used to derive value propositions. A two-alternative forced-choice paradigm and probabilistic choice models were used to investigate hearing aid users' preferences for the value propositions through an online platform. Study sample: Twelve hearing aid users (mean age 70, range 59-70) and eleven clinicians were interviewed. A total of 173 experienced hearing aid users evaluated the value propositions. Results: Twenty-nine value propositions as described by patients, clinicians, and hearing care experts where identified, from which twenty-one value propositions were evaluated. Results of the pair-wise evaluation method show that the value propositions judged to be the most important for the hearing aid users were: "13. To solve the hearing problem you have", "09. Thorough diagnosis of the hearing", and "16. The hearing aid solution is adapted to individual needs", which are related to finding the correct hearing solution and to be considered in the process. The value propositions judged to be least important were: "04 Next of kin and others involved in the process", "26. To be in the same room as the practitioner", and "29. The practitioner's human characteristics", related to the involvement of others in the process and the proximity and personal manner of the practitioners.

Coronary Artery Disease Detected by Low Frequency Heart Sounds.

OBJECTIVES: Previous studies have observed an increase in low frequency diastolic heart sounds in patients with coronary artery disease (CAD). The aim was to develop and validate a diagnostic, computerized acoustic CAD-score based on heart sounds for the non-invasive detection of CAD. METHODS: Prospective study enrolling 463 patients referred for elective coronary angiography. Pre-procedure non-invasive recordings of heart sounds were obtained using a novel acoustic sensor. A CAD-score was defined as the power ratio between the 10-90 Hz frequency spectrum and the 90-300 Hz frequency spectrum of the mid-diastolic heart sound. Quantitative coronary angiography analysis was performed by a blinded core laboratory and patients grouped according to the results: obstructive CAD defined by the presence of at least one ≥ 50% stenosis, non-obstructive CAD as patients with a maximal stenosis in the 25-50% interval and non-CAD as no coronary lesions exceeding 25%. We excluded patients with potential confounders or incomplete data (n = 245). To avoid over-fitting the final cohort of 218 patients was randomly divided into to a training group for development (n = 127) and a validation group (n = 91). RESULTS: In both the training and the validation group the CAD-score was significantly increased in CAD patients compared to non-CAD patients (p < 0.0001). In the validation group the area under the receiver-operating curve was 77% (95% CI 63-91%). Sensitivity was 71% (95% CI 59-82%) and specificity 64% (95% CI 45-83%). CONCLUSION: The acoustic CAD-score is a new, inexpensive, non-invasive method to detect CAD, which may supplement clinical risk stratification and reduce the need for subsequent non-invasive and invasive testing.

Is it necessary to penalize impulsive noise +5 dB due to higher risk of hearing damage?

It is studied whether the +5 dB penalty for impulsiveness established by ISO 1999:1990 accounts for a higher risk of noise-induced hearing loss. A total of 16 normal-hearing human subjects were exposed for 10 min to two types of binaural industrial-recordings: (1) a continuous broad-band noise normalized to L(EX,8 h)=80 dBA and (2) the combination of the previous stimulus with an impulsive noise normalized to L(EX,8 h)=75+5(db penalty)=80 dBA (peak level 117 dBC and repetition rate of 0.5 impacts per second). Distortion product otoacoustic emissions (DPOAEs) were measured in a broad frequency range before and in the following 90 min after the exposure. The group results show that the continuous exposure had a bigger impact on DPOAE levels, with a maximum DPOAE shift of approximately 5 dB in the frequency range of 2-3.15 kHz during the first 10 min of the recovery. No evident DPOAE shift is seen for the impulsive + continuous stimulus. The results indicate that the penalty overestimated the effects on DPOAE levels and support the concept that the risk of hearing loss from low-level impulses may be predicted on an equal-energy basis.

Confidence Limits of Word Identification Scores Derived Using Nonlinear Quantile Regression.

The relation between degree of sensorineural hearing loss and maximum speech identification scores (PBmax) is commonly used in audiological diagnosis and rehabilitation. It is important to consider the relation between the degree of hearing loss and the lower boundary of PBmax, as the PBmax varies largely between subjects at a given degree of hearing loss. The present study determines the lower boundary by estimating the lower limit of the one-tailed 95% confidence limit (CL) for a Dantale I, word list, in a large group of young and older subjects with primarily sensorineural hearing loss. PBmax scores were measured using Dantale I, at 30 dB above the speech reception threshold or at the most comfortable level from 1,961 subjects with a wide range of pure-tone averages. A nonlinear quantile regression approach was applied to determine the lower boundary (95% CL) of PBmax scores. At a specific pure-tone average, if the measured PBmax is poorer than the lower boundary (95% CL) of PBmax, it may be considered disproportionately poor.

Recovery of distortion-product otoacoustic emissions after a 2-kHz monaural sound-exposure in humans: effects on fine structures.

A better understanding of the vulnerability of the fine structures of distortion-product otoacoustic emissions (DPOAEs) after acoustic overexposure may improve the knowledge about DPOAE generation, cochlear damage, and lead to more efficient diagnostic tools. It is studied whether the DPOAE fine structures of 16 normal-hearing human subjects are systematically affected after a moderate monaural sound-exposure of 10 min to a 2-kHz tone normalized to an exposure level L(EX,8h) of 80 dBA. DPOAEs were measured before and in the following 70 min after the exposure. The experimental protocol allowed measurements with high time and frequency resolution in a 1/3-octave band centered at 3 kHz. On average, DPOAE levels were reduced approximately 5 dB in the entire measured frequency-range. Statistically significant differences in pre- and post-exposure DPOAE levels were observed up to 70 min after the end of the sound exposure. The results show that the effects on fine structures are highly individual and no systematic change was observed.

Sentence-Based Experience Logging in New Hearing Aid Users.

Purpose The aim of this study was to develop a tool to gain insight into the daily experiences of new hearing aid users and to shed light on aspects of aided performance that may not be unveiled through standard questionnaires. Method The tool is developed based on clinical observations, patient experiences, expert involvement, and existing validated hearing rehabilitation questionnaires. Results An online tool for collecting data related to hearing aid use was developed. The tool is based on 453 prefabricated sentences representing experiences within 13 categories related to hearing aid use. Conclusions The tool has the potential to reflect a wide range of individual experiences with hearing aid use, including auditory and nonauditory aspects. These experiences may hold important knowledge for both the patient and the professional in the hearing rehabilitation process.

Overexposure effects of a 1-kHz tone on the distortion product otoacoustic emission in humans.

The effects of overexposure on the properties of distortion product otoacoustic emissions (DPOAEs) are investigated. In total, 39 normal-hearing humans were monaurally exposed to a 1-kHz tone lasting for 3 min at an equivalent threshold sound-pressure level of 105.5 dB. The effects of overexposure were studied in two experiments (1) on the broadband DPOAE and (2) on the DPOAE fine structure, measured using a higher frequency resolution in a narrower frequency range. The obtained DPOAE shifts were compared to temporary threshold shift (TTS) obtained after a similar exposure. Similarities between DPOAE shifts and TTS were found in the affected frequency range and the time course of recovery. The amount of TTS was higher in the early recovery time (1-4-min postexposure), but similar to the DPOAE shift (even in absolute terms) at later recovery times (5-20-min postexposure). The DPOAE fine structure was not systematically changed after the exposure.

Distortion-Product Otoacoustic Emission Measured Below 300 Hz in Normal-Hearing Human Subjects.

Physiological noise levels in the human ear canal often exceed naturally low levels of otoacoustic emissions (OAEs) near the threshold of hearing. Low-frequency noise, and electronic filtering to cope with it, has effectively limited the study of OAE to frequencies above about 500 Hz. Presently, a custom-built low-frequency acoustic probe was put to use in 21 normal-hearing human subjects (of 34 recruited). Distortion-product otoacoustic emission (DPOAE) was measured in the enclosed ear canal volume as the response to two simultaneously presented tones with frequencies f 1 and f 2. The stimulus-frequency ratio f 2/f 1 was varied systematically to find the "optimal" ratio evoking the largest level at 2 f 1-f 2 frequencies 87.9, 176, and 264 Hz. No reference data exist in this frequency region. Results show that DPOAE exists down to at least 87.9 Hz, maintaining the bell-shaped dependence on the f 2/f 1 ratio known from higher frequencies. Toward low frequencies, however, the bell broadens and the optimal ratio increases proportionally to the bandwidth of an auditory filter as defined by the equivalent rectangular bandwidth. The DPOAE phase rotates monotonously as a function of the stimulus ratio, and its slope trend supports the notion of a lack of scaling symmetry in the apex of the cochlea.

Separation and characterization of maternal cardiac and vascular sounds in the third trimester of pregnancy.

OBJECTIVE: To characterize the vascular sounds of the uteroplacental blood flow obtained by microphones. METHODS: The present retrospective study took place in an anechoic chamber facility at Aalborg University, Aalborg, Denmark, in 2012, and included pregnant participants aged 18-40 years with a singleton pregnancy at 32-36 weeks and a parity of 0-2. Abdominal Doppler ultrasonography was performed bilaterally on the uterine arteries. Subsequently, in the same positions, sound recordings were performed with microphones. The derived raw sound signal was separated into two frequency ranges, and characterized accordingly. RESULTS: The mean pregnancy length among 25 participants was 33.6 ± 2.0 weeks. The pulsatility index of the uterine artery was 0.67 ± 0.24. All 50 recordings displayed the first and second maternal heart sounds (frequency 25-100 Hz), and in 17 of 50 recordings, maternal vascular murmurs (frequency 200-800 Hz) were present. The average pulse wave velocity between the maternal aortic valve and the uterine artery was estimated to be 6.6 ± 1.5 m/s. CONCLUSION: Maternal vascular murmurs in the frequency range of 200-800 Hz were identified as a possible marker of abnormal uteroplacental blood flow, and provide a means to measure the arterial pulse wave velocity.

Distortion product otoacoustic emission of symphony orchestra musicians before and after rehearsal.

The 2f1-f2 distortion product otoacoustic emission (DPOAE) and hearing levels are obtained for 12 normal-hearing symphony orchestra musicians both before and after their rehearsal. The DPOAE fine structures are determined and analyzed according to the character and prevalence of ripples. Hearing levels, DPOAE levels, and DPOAE fine structures before and after rehearsal are similar, indicating that no or marginal temporary change of the state of hearing were caused by the exposure. The data were further compared to similar data for occupationally nonexposed subjects, one group which was age and gender matched, and other two groups of younger individuals (one group with better hearing levels than the other). The data for the age and gender matched group compared well with the musicians data (and the data for the group of better-hearing younger individuals). In general, the analyses of hearing thresholds and DPOAE data thus lead to the same conclusions concerning the state of hearing.

Distortion product otoacoustic emission fine structure analysis of 50 normal-hearing humans.

When distortion product otoacoustic emissions (DPOAEs) are measured with a high-frequency resolution, the DPOAE shows quasi-periodic variations across frequency, called DPOAE fine structure. In this study the DPOAE fine structure is determined for 50 normal-hearing humans using fixed primary levels of L1/L2 = 65/45 dB. An algorithm is developed, which characterizes the fine structure ripples in terms of three parameters: ripple spacing, ripple height, and ripple prevalence. The characteristic patterns of fine structure can be found in the DPOAE of all subjects, though the DPOAE fine structure characteristics are individual and vary from subject to subject. On average the ripple spacing decreases with increasing frequency from 1/8 oct at 1 kHz to 3/32 oct at 5 kHz. The ripple prevalence is two to three ripples per 1/3 oct, and ripple heights of up to 32 dB could be detected. The 50 normal-hearing subjects were divided into two groups, the subjects of group A having slightly better hearing levels than subjects of group B. The subjects of group A have significantly higher DPOAE levels. The overall prevalence of fine structure ripples do not differ between the two groups, but are higher and narrower for subjects of group B than for group A.

Coupling of earphones to human ears and to standard coupler.

A standardized acoustical coupler should enable the calibration of audiometric earphones which ensures that the hearing thresholds determined in the audiometric measurement are independent of the earphone type. This requires that the coupler approximates the average human ear closely. Nevertheless, the differences among earphones as well as between human ears and the coupler affect the results of the audiometric measurements inducing uncertainty. As the mentioned differences are related to the coupling of different earphones to human ears and to a standardized coupler, the effects of this coupling are investigated by measuring the transfer functions from input voltage of the earphone terminals to the pressure at the ear canal entrance in two situations: open and blocked canals. Since the "ear canal entrance" is not well-defined for the coupler, transfer function measurements in the coupler were carried out in a similar way but at different depths. In order to describe and compare the earphone couplings, the pressure divisions at the entrance of the ear canal are calculated from the measured transfer functions. The results indicate that significant difference appears among sound pressures generated in different individuals' ears. Also, the earphone couplings to human ears and to the coupler differ considerably.