Loudness Scaling Research Articles

Audiometric characteristics of two Dutch families with non-ocular Stickler syndrome (COL11A2)

ObjectiveTo evaluate hearing impairment and cochlear function in non-ocular Stickler syndrome. Study designMultifamily study. Patients & methodsTen patients from two different families with non-ocular Stickler syndrome (Stickler syndrome type 3) were included. Six members of the first family and four members of the second family participated in this study. Otorhinolaryngologic examinations were performed. Pure-tone and speech audiograms were obtained. Longitudinal analysis was performed. Psychophysical measurements, including loudness scaling, gap detection, difference limen for frequency and speech perception in noise were administered to assess cochlear function at a deeper level. ResultsAffected individuals in the first family were carriers of a heterozygous splice donor mutation in the COL11A2 gene. Affected individuals in the second family were carriers of a novel heterozygous missense mutation in COL11A2. Both families showed bilateral, non-progressive hearing impairment with childhood onset. The severity of the hearing impairment exhibited inter- and intrafamilial variability and was mostly mild to moderate. The results of the psychophysical measurements were similar to those previously published for DFNA8/12 (TECTA) and DFNA13 (COL11A2) patients and thus consistent with an intra-cochlear conductive hearing impairment. This is in line with the theory that mutations in COL11A2 affect tectorial membrane function. ConclusionHearing impairment in non-ocular Stickler syndrome is characterized by non-progressive hearing loss, present since childhood, and mostly mild to moderate in severity. Psychophysical measurements in non-ocular Stickler patients were suggestive of intra-cochlear conductive hearing impairment.

Clonazepam Quiets tinnitus: a randomised crossover study with Ginkgo Biloba

ObjectiveTo assess the effect of Ginkgo biloba and clonazepam, a γ-aminobutyric acid (GABA)-receptor agonist, upon tinnitus.MethodsThis was an open-label, randomised, crossover study. 27 men and 11 women (aged 16–80 (mean...

Feasibility of an objective electrophysiological loudness scaling: A kernel-based novelty detection approach

The objective of our research is to structure a foundation for an electrophysiological loudness scaling measurement, in particular to estimate an uncomfortable loudness (UCL) level by using the hybrid wavelet-kernel novelty detection (HWND). Late auditory evoked potentials (LAEPs) were obtained from 20 normal hearing adults. These LAEPs were stimulated by 4 intensity levels (60 decibel (dB) sound pressure level (SPL), 70 dB SPL, 80 dB SPL, and 90 dB SPL). We have extracted the habituation correlates in LAEPs by using HWND. For this, we employed a lattice structure-based wavelet frame decompositions for feature extraction combined with a kernel-based novelty detector. The group results showed that the habituation correlates degrees, i.e., relative changes within the sweep sequences, were significantly different among 60 dB SPL, 70 dB SPL, 80 dB SPL, and 90 dB SPL stimulation level, independently from the intensity related amplitude information in the averaged LAEPs. At these particular intensities, 60% of the subjects show the correlation between the novelty measures and the stimulation levels resembles a loudness scaling function, in reverse. In this paper, we have found a correlation in between the novelty measures and loudness perception as well. We have found that high ranges of loudness levels such as loud, upper level and too loud show generally 4.88% of novelty measures and comfortable ranges of loudness levels, i.e., soft, comfortable but soft, comfortable loud and comfortable but loud are generally have 12.29% of novelty measures. Additionally, we demonstrated that our sweep-to-sweep basis of post processing scheme is reliable for habituation extraction and offers an advantage of reducing experimental time as the proposed scheme need less than 20% of single sweeps in comparison to the amount that are commonly used in arithmetical average for a meaningful result. We assessed the feasibility of habituation correlates for an objective loudness scaling. With respect to this first feasibility study, the presented results are promising when using the described signal processing and machine learning methodology. For the group results, the novelty measures approach is able to discriminate 60 dB, 70 dB, 80 dB and 90 dB stimulated sweeps. In addition, a correlation between the novelty measures and the subjective loudness scaling is observed. However, more loudness perception and frequency specific experiments need to be conducted to determine the UCL novelty measures threshold as well as clinically oriented studies are necessary to evaluate whether this approach might be used in the objective hearing instrument fitting procedures.

Neural Coding of Sound Intensity and Loudness in the Human Auditory System

Inter-individual differences in loudness sensation of 45 young normal-hearing participants were employed to investigate how and at what stage of the auditory pathway perceived loudness, the perceptual correlate of sound intensity, is transformed into neural activation. Loudness sensation was assessed by categorical loudness scaling, a psychoacoustical scaling procedure, whereas neural activation in the auditory cortex, inferior colliculi, and medial geniculate bodies was investigated with functional magnetic resonance imaging (fMRI). We observed an almost linear increase of perceived loudness and percent signal change from baseline (PSC) in all examined stages of the upper auditory pathway. Across individuals, the slope of the underlying growth function for perceived loudness was significantly correlated with the slope of the growth function for the PSC in the auditory cortex, but not in subcortical structures. In conclusion, the fMRI correlate of neural activity in the auditory cortex as measured by the blood oxygen level-dependent effect appears to be more a linear reflection of subjective loudness sensation rather than a display of physical sound pressure level, as measured using a sound-level meter.

Audiometric characteristics of a Dutch family with Muckle-Wells syndrome

Description of the audiometric and vestibular characteristics of a Dutch family with Muckle-Wells syndrome (MWS). Examination of all family members consisted of pure tone audiometry, otoscopy and genetic analysis. In addition, a selected group underwent speech audiometry, vestibulo-ocular examination, acoustic reflex testing and tests assessing loudness scaling, gap detection, difference limen for frequency and speech perception in noise. Linear regression analyses were performed on the audiometric data. Six clinically affected family members participated in this study and all were carriers of a p.Tyr859His mutation in the NLPR3 gene. Most affected family members reported bilateral, slowly progressive hearing impairment since childhood. Hearing impairment started at the high frequencies and the low- and mid-frequency threshold values deteriorated with advancing age. Annual threshold deterioration (ATD) ranged from 1.3 to 1.9 dB/year with the highest values at the lower frequencies. Longitudinal linear regression analysis demonstrated significant progression for a number of frequencies in five individuals. Speech recognition scores were clearly affected. However, these individuals tended to have higher speech recognition scores than presbyacusis patients at similar PTA 1,2,4 kHz levels. The loudness growth curves were steeper than those found in individuals with normal hearing, except for one family member (individual IV:6). Suprathreshold measurements, such as difference limen for frequency (DL f), gap detection and particularly speech perception in noise were within the normal range or at least close to data obtained in two groups of patients with a so-called conductive type of hearing loss, situated in the cochlea. Hearing impairment in MWS is variable and shows resemblance to previously described intra-cochlear conductive hearing impairment. This could be helpful in elucidating the pathogenesis of hearing impairment in MWS. Other associated symptoms of MWS were mild and nonspecific in the present family. Therefore, even without any obvious syndromic features, MWS can be the cause of sensorineural hearing impairment, especially when combined with (mild) skin rash and musculoskeletal symptoms. An early diagnosis of MWS is essential to prevent irreversible damage from amyloidosis. The effect of IL-1β inhibitors on hearing impairment is more controversial, but an early start of treatment seems to be essential. Therefore, our results are of importance in patient care and counselling.

Temporal integration of loudness measured using categorical loudness scaling and matching procedures

Temporal integration of loudness of 1 kHz tones with 5 and 200 ms durations was assessed in four subjects using two loudness measurement procedures: categorical loudness scaling (CLS) and loudness matching. CLS provides a reliable and efficient procedure for collecting data on the temporal integration of loudness and previously reported nonmonotonic behavior observed at mid-sound pressure level levels is replicated with this procedure. Stimuli that are assigned to the same category are effectively matched in loudness, allowing the measurement of temporal integration with CLS without curve-fitting, interpolation, or assumptions concerning the form of the loudness growth function.

Assessment of auditory nonlinearity for listeners with different hearing losses using temporal masking and categorical loudness scaling

A dysfunction or loss of outer hair cells (OHC) and inner hair cells (IHC), assumed to be present in sensorineural hearing-impaired listeners, affects the processing of sound both at and above the listeners’ hearing threshold. A loss of OHC may be responsible for a reduction of cochlear gain, apparent in the input/output function of the basilar membrane and steeper-than-normal growth of loudness with level (recruitment). IHC loss is typically assumed to cause a level-independent loss of sensitivity. In the current study, parameters reflecting individual auditory processing were estimated using two psychoacoustic measurement techniques. Hearing loss presumably attributable to IHC damage and low-level (cochlear) gain were estimated using temporal masking curves (TMC). Hearing loss attributable to OHC (HLOHC) was estimated using adaptive categorical loudness scaling (ACALOS) and by fitting a loudness model to measured loudness functions. In a group of listeners with thresholds ranging from normal to mild-to-moderately impaired, the loss in low-level gain derived from TMC was found to be equivalent with HLOHC estimates inferred from ACALOS. Furthermore, HLOHC estimates obtained using both measurement techniques were highly consistent. Overall, the two methods provide consistent measures of auditory nonlinearity in individual listeners, with ACALOS offering better time efficiency.

Cochlea‐scaled entropy predicts speech intelligibility when intensity is scaled as linear amplitude or as loudness, but not when scaled logarithmically.

Stilp and Kluender [Proc. Natl. Acad. Sci. 107, 12387–12392 (2010)] reported sentence intelligibility to be well‐predicted by measures of sensory change over time [cochlea‐scaled spectral entropy (CSE)] and not consonants, vowels, or duration of signal replaced. As greater amounts of CSE were replaced by noise, intelligibility worsened. They calculated CSE as Euclidean distances between spectra defined by linear amplitude as a function of equal rectangular bandwidth (ERB). The present experiments compare measures of speech intelligibility as a function of CSE when amplitude is measured on a linear scale as before and when log‐scaled (dB) or loudness‐scaled (sone). Listeners typed all words they understood after hearing sentences with 80‐ and 112‐ms segments replaced by speech‐shaped noise. Log‐scaled (dB) CSE was a poor predictor of performance. Both linear‐scaled and loudness‐scaled measures of CSE predict intelligibility very well, replicating Stilp and Kluender. Linear and loudness scales will be discussed in the context of upward spread of masking and two‐tone suppression as they relate to speech signals. These perceptual findings suggest that conventional use of spectrograms (linear frequency × dB intensity) could systematically misinform researchers concerning properties of speech signals that are most useful to listeners. [Work supported by NIDCD.]

Utility of categorical loudness scaling to estimate the outer- and inner-hair-cell-loss-related components of hearing impairment.

Sensorineural hearing loss is mainly accompanied by a reduction or dysfunction of outer hair cells (OHCs) and inner hair cells (IHCs) in the cochlea. A dysfunction of OHCs is often assumed to correspond to an expansive component and a dysfunction of IHCs to an attenuating component of hearing loss. This study presents a method for assessing OHC and IHC losses from categorical loudness curves using adaptive categorical loudness scaling (ACALOS). A loudness model was used to fit modeled loudness curves to measured loudness curves by adjusting a model parameter HLOHC that quantifies the amount of hearing loss related to the dysfunction of OHCs relative to total hearing loss. This parameter HLOHC was compared to corresponding parameters extracted using temporal masking curves (TMCs) in 16 listeners with different audiometric thresholds. The results showed that both ACALOS and TMCs estimated HLOHC consistently, whereas ACALOS offers much more time-efficiency and about the same accuracy as TMCs. Since ACALOS is an easy and natural task for inexperienced listeners and because of the high time-efficiency, ACALOS appears to be a good candidate for the assessment of this part of the suprathreshold processing of sensorineural hearing-impaired listeners in clinical practice. [Work supported by the DFG (Grant No. SFB TRR31).]

Transitioning Hearing Aid Users with Severe and Profound Loss to a New Gain/Frequency Response: Benefit, Perception, and Acceptance

Adults with severe and profound hearing loss tend to be long-term, full-time users of amplification who are highly reliant on their hearing aids. As a result of these characteristics, they are often reluctant to update their hearing aids when new features or signal-processing algorithms become available. Due to the electroacoustic constraints of older devices, many severely and profoundly hearing-impaired adults continue to wear hearing aids that provide more low- and mid-frequency gain and less high-frequency gain than would be prescribed by the National Acoustic Laboratories' revised formula with profound correction factor (NAL-RP). To investigate the effect of a gradual change in gain/frequency response on experienced hearing-aid wearers with moderately severe to profound hearing loss. Double-blind, randomized controlled trial. Twenty-three experienced adult hearing-aid users with severe and profound hearing loss participated in the study. Participants were selected for inclusion in the study if the gain/frequency response of their own hearing aids differed significantly from their NAL-RP prescription. Participants were assigned either to a control or to an experimental group balanced for aided ear three-frequency pure-tone average (PTA) and age. Participants were fitted with Siemens Artis 2 SP behind-the-ear (BTE) hearing aids that were matched to the gain/frequency response of their own hearing aids for a 65 dB SPL input level. The experimental group progressed incrementally to their NAL-RP targets over the course of 15 wk, while the control group maintained their initial settings throughout the study. Aided speech discrimination testing, loudness scaling, and structured questionnaires were completed at 3, 6, 9, 12, and 15 wk postfitting. A paired comparison between the old and new gain/frequency responses was completed at 1 and 15 wk postfitting. Statistical analysis was conducted to examine differences between the experimental and control groups and changes in objective performance and subjective perception over time. The results of the study showed that participants in the experimental group were subjectively accepting of the changes to their amplification characteristics, as evidenced by nonsignificant changes in the ratings of device performance over time. Perception of loudness, sound quality, speech intelligibility, and own voice volume did not change significantly throughout the study. Objectively, participants in the experimental group demonstrated poorer speech discrimination performance as the study progressed, although there was no change in objective loudness perception. According to the paired comparison, there was an overall subjective preference for the original gain/frequency response among all participants, although participants in the experimental group did show an increase in preference for the NAL-RP response by the end of the study. Based on the findings of this study, we suggest that undertaking a gradual change to a new gain/frequency response with severely and profoundly hearing-impaired adults is a feasible procedure. However, we recommend that clinicians select transition candidates carefully and initiate the procedure only if there is a clinical reason for doing so. A validated prescriptive formula should be used as a transition target, and speech discrimination performance should be monitored throughout the transition.

Anpassung von Cochlea-Implantat-Sprachprozessoren

The rehabilitation outcome with the cochlear implant is, among other factors, mainly affected by the fitting of the system to the individual needs of the patient. Accompanying the rapid advances in the technical development of these hearing prostheses and the surgical approach there has been a marked extension of the indication criteria. Children and adults who receive deaf benefit as well as patients with residual hearing who do not attain a sufficient gain in speech intelligibility with the best possible hearing aid can be helped with cochlear implants. Congenitally deaf children are provided with cochlear implants very successfully at the age of one and the bilateral implantation has become standard clinical procedure whenever the indication criteria are fulfilled for both ears. The group of cochlear implant patients is very heterogeneous with respect to their anatomic conditions, listening experiences and particular needs. That is why a wide inventory of methods is necessary to manage appropriately the patient specific fitting of the cochlear implant system. Interactive psychoacoustic procedures, which have proved their worth in audiology and hearing aid fitting, are helpful for adolescents and adults. Especially the categorical loudness scaling can be very helpful. Particularly with small children and uncooperative patients, the audiologists like to base their efforts on the results of objective investigations in the iterative process of fitting. These measurements can be done during surgery as well as in the long-lasting period of fine tuning. The electrically evoked stapedius reflex and the telemetric recording of electrically evoked potentials of the nervus acusticus are especially helpful. Information for the parameter selection that is necessary during the process of fitting is available from the accompanying evaluations on different levels of the auditory processing.

Repetitive transcranial magnetic stimulation (rTMS) for treatment of chronic tinnitus

Objective There is compelling evidence that tinnitus is associated with functional alterations in the central nervous system. Repetitive transcranial magnetic stimulation (rTMS) is a potent tool for modifying neural activity at the stimulated area and at a distance along the functional anatomical connections. Depending on the stimulation parameters, cortical networks can be functionally disturbed or modulated in their activities. Low-frequency rTMS has been shown to result in a decrease in cortical excitability. The technique can alleviate tinnitus by modulating the excitability of neurons in the auditory cortex. We aimed to investigate the effects of low-frequency rTMS in patients and determine the factors that predict a beneficial outcome with rTMS treatment. Methods Sixteen patients (male 10, female 6) with chronic tinnitus underwent low-frequency (1 Hz) rTMS (intensity: 110% motor threshold; number of stimuli: 1200) to the left auditory cortex. The treatment outcome was assessed with a visual analog scale (VAS) of loudness, annoyance and duration, loudness balance test, and tinnitus handicap inventory (THI). Therapeutic success was studied according to the patients’ clinical characteristics. Results A significant reduction in the VAS (loudness and annoyance) occurred immediately after rTMS, with a gradual return to pretreatment levels after 7 days. The tinnitus patients with sudden deafness were significant resistant to rTMS treatment compared with those diagnosed with age-related hearing loss. Conclusion These results support the potential of rTMS as a new therapeutic tool for the treatment of chronic tinnitus. Because this study was performed with a small sample size and showed high interindividual variability in treatment effects, further development of the technique is needed before it can be recommended for clinical applications.

Spectral loudness summation takes place in the primary auditory cortex

Auditory functional magnetic resonance imaging (fMRI) was used to assess neural activation in the human auditory brainstem (AB) and cortex (AC) as a function of bandwidth (BW). We recorded brain activation of 22 normal hearing listeners induced by band pass filtered pink noise stimuli with equal sound pressure level of 70 dB SPL. Tested bandwidths were 50, 500, 1,500, 3,000, 6,000, and 8,000 Hz. The center frequency was 4,000 Hz. Categorical loudness scaling had been performed in a silent booth with all of these stimuli. Loudness as a function of bandwidth followed a concave-shaped curve which reflected the influence of spectral loudness summation (SLS) for higher BW and the influence of large amplitude fluctuations for very low BW, which itself could be explained by peak-listening. While neural activation of the AB, as measured by the percent signal change from baseline (PSC), was tuned to the physical BW of the stimuli in a straight linear fashion, the trend of perceived loudness as a function of BW was reflected in several aspects by corresponding neural activation in the primary auditory cortex (PAC). Finally, from the absolute differences of the PSC between PAC and AB, gains in perceived loudness associated with SLS and the effect of large amplitude fluctuations could be predicted with an accuracy of 1-2 dB for the whole group of participants.

Development of a Software Tool Using Deterministic Logic for the Optimization of Cochlear Implant Processor Programming

An intelligent agent, Fitting to Outcomes eXpert, was developed to optimize and automate Cochlear implant (CI) programming. The current article describes the rationale, development, and features of this tool. Cochlear implant fitting is a time-consuming procedure to define the value of a subset of the available electric parameters based primarily on behavioral responses. It is comfort-driven with high intraindividual and interindividual variability both with respect to the patient and to the clinician. Its validity in terms of process control can be questioned. Good clinical practice would require an outcome-driven approach. An intelligent agent may help solve the complexity of addressing more electric parameters based on a range of outcome measures. A software application was developed that consists of deterministic rules that analyze the map settings in the processor together with psychoacoustic test results (audiogram, A(section sign)E phoneme discrimination, A(section sign)E loudness scaling, speech audiogram) obtained with that map. The rules were based on the daily clinical practice and the expertise of the CI programmers. The data transfer to and from this agent is either manual or through seamless digital communication with the CI fitting database and the psychoacoustic test suite. It recommends and executes modifications to the map settings to improve the outcome. Fitting to Outcomes eXpert is an operational intelligent agent, the principles of which are described. Its development and modes of operation are outlined, and a case example is given. Fitting to Outcomes eXpert is in use for more than a year now and seems to be capable to improve the measured outcome. It is argued that this novel tool allows a systematic approach focusing on outcome, reducing the fitting time, and improving the quality of fitting. It introduces principles of artificial intelligence in the process of CI fitting.

Reliability of Categorical Loudness Scaling and Its Relation to Threshold

To further examine the reliability of categorical loudness scaling (CLS) for individual loudness categories and for the slope of the CLS functions. And, to evaluate the relationship between CLS and audiometric threshold. CLS functions were obtained in 74 subjects, 58 with hearing loss and 16 with normal hearing. CLS functions were measured at three frequencies (1, 2, and 4 kHz) in two separate sessions separated by as little as 1 wk and as much as 6 mo. Reliability of mean and median levels within each loudness category was assessed using SDs and correlation coefficients. Lines were fit to the CLS functions, and slopes of the lines were used to assess reliability and the relation between CLS and audiometric threshold. Similar reliability for CLS measurements was observed in both normal-hearing and hearing-impaired subjects at all frequencies. Across both groups of subjects, correlations describing the reliability of mean stimulus level within category exceeded 0.92 at all frequencies. In addition, SDs of the mean stimulus-level difference between visits ranged from 6.6 to 7.8 dB, depending on frequency. The correlation between the slope of a straight line fitted to the entire CLS function and audiometric threshold collapsed across frequencies was 0.72. Two line segments were then fit to the CLS function: one segment was fit to the soft portion of the CLS function (categorical units < or =20) and the other segment to the loud portion (categorical unit >20). Slopes of the line fit to the entire CLS function and of the line fit to the soft portion of the CLS function were both reliable across sessions. The slope of the line fit to the soft portion increased as audiometric threshold increased, with the correlations greater than 0.86 at all frequencies. No relationship was observed between slope of the line fit to the loud portion of the CLS function and audiometric threshold. Iso-loudness contours were constructed from the CLS data and used to determine the gain that would be needed to produce "normal" loudness percepts for hearing-impaired individuals. Within-subject CLS measurements were reliable across sessions both for individual loudness categories and for slope of the CLS functions. In addition, the slope of the low-level portion of the CLS function varied in a predictable manner with audiometric threshold, with slope increasing as audiometric threshold increased. Finally, gain as a function of input level needed to provide loudness percepts for individuals with hearing loss equal to the loudness percepts of normal-hearing individuals can be estimated from audiometric threshold. This finding supports the assumption that audiometric threshold and response growth (loudness) are both determined by the same underlying cochlear mechanisms.

Tinnitus Intensity Dependent Gamma Oscillations of the Contralateral Auditory Cortex

BackgroundNon-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores.Methods and FindingsIn unilateral tinnitus patients (N = 15; 10 right, 5 left) source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p<0.05).ConclusionAuditory phantom percepts thus show similar sound level dependent activation of the contralateral auditory cortex as observed in normal audition. In view of recent consciousness models and tinnitus network models these results suggest tinnitus loudness is coded by gamma band activity in the contralateral auditory cortex but might not, by itself, be responsible for tinnitus perception.

Intratympanic methylprednisolone injections for subjective tinnitus

This study aimed to determine whether intratympanically injected methylprednisolone is effective in treating subjective tinnitus refractory to medical treatment. Prospective, randomised, placebo-controlled, single-blinded study. Seventy adult patients with subjective tinnitus of cochlear origin were randomly assigned to receive intratympanic injection of either methylprednisolone or saline solution. The treatment protocol comprised three intratympanic injections, one per week for three weeks. Improvement in tinnitus severity was measured by a self-rated tinnitus loudness scale and by the tinnitus severity index, at baseline and two weeks after the last injection. Data for 59 patients were available for analysis. There was no significant difference between the two treatment groups regarding age, sex, pure tone average, pretreatment tinnitus intensity, tinnitus laterality or tinnitus duration. There was a significant post-treatment improvement in self-rated tinnitus loudness scale results in both groups. No significant post-treatment changes in the tinnitus severity index individual and total scores were observed in either group. The most frequently encountered side effects were pain during injection, vertigo, a burning sensation around the ear and in the throat, and a bitter taste. A burning sensation and bitter taste were observed more often in the methylprednisolone group compared with the placebo group. The results of this study indicate that intratympanic methylprednisolone has no benefit, compared with placebo, for the treatment of subjective tinnitus of cochlear origin refractory to medical treatment.

Measuring Tinnitus Loudness Using Constrained Psychophysical Scaling

We measured tinnitus loudness using a new method of psychophysical scaling with the aim of introducing a potentially useful new procedure to the literature. Fourteen adults reporting tinnitus were trained to use a standardized loudness scale, and then they used that response scale to assess loudness of nonstandard stimuli and of their tinnitus. We also measured tinnitus loudness and pitch using a computer-based matching procedure, and we measured the impact of tinnitus on daily living using the Tinnitus Handicap Inventory (THI; C. W. Newman, G. P. Jacobson, & J. B. Spitzer, 1996) for those 14 individuals and an additional 2 participants. Results and Conclusions Our 14 trained participants judged loudness similarly to normal hearing participants for pure tones at normal hearing, nontinnitus frequencies-implying that their judgments of tinnitus loudness were valid. Constrained scaling of tinnitus loudness yielded measurements that were substantially greater than the sensation level of sounds matched to tinnitus loudness. Our total of 16 participants fell into 2 groups on the basis of hearing loss, extent of abnormal loudness growth at the tinnitus frequency, and several aspects of tinnitus experience. Finally, as previously found, there was little correlation between tinnitus loudness, no matter how measured, and the impact of tinnitus on daily life as measured by the THI.

Cochlear implant and hearing aid: a new approach to optimizing the fitting in this bimodal situation

More and more patients with residual hearing on the contralateral side are becoming candidates for cochlear implants (CI) surgery due to increasing CI. The major benefits of regular binaural hearing are spatial hearing, localization, and signal source discrimination in both quiet and noisy surroundings. In most of the reports, hearing aid fitting was carried out without balancing both the devices. Twelve children and eight adults with residual hearing on the non-operated side were binaurally fitted. Our fitting procedure for the hearing aid was based on the desired sensation level [i/o] method. A loudness scaling was used to adjust the loudness perception monaurally and to balance the volume of both devices. Speech audiometry in quiet and noisy surroundings was conducted both monaurally and in the bimodal mode. The fitting was modified according to the respective test results. In all children and six adults, a measurable gain and/or a subjective improvement of speech perception was achieved. Two adult patients did not accept the new fitting. In seven younger children, loudness scaling was impossible to perform because of age. This was also the case with speech audiometry for two children. A structured bimodal fitting using loudness scaling for both the cochlear implant and the hearing aid results in a subjective and objective amelioration of the patient's hearing and speech perception.

A speech quality metric based on a cochlear model.

Noise, distortion, nonlinear signal-processing algorithms, and linear filtering can all affect the sound quality of a hearing aid. The sound quality, in turn, can have a strong impact on the success of the device. The general approach in designing a quality metric is to compare the degraded signal with a clean (unprocessed) reference signal; the comparison generally involves comparing one or more features extracted from the signals. In this presentation, features are extracted from a computationally efficient model of the auditory periphery. The model includes the middle ear, an auditory filter bank, dynamic-range compression, two-tone suppression, and loudness scaling. The first step is a metric for noise, distortion, and nonlinear signal processing. The noise and nonlinear metric focuses on differences in the short-time signal behavior. The second step is a metric that focuses on the changes in the long-term average spectrum caused by linear filtering. The third and final step is to merge the noise and nonlinear metric with the linear filtering metric to produce a composite sound quality metric that can be applied to an arbitrary signal-processing system. The metrics give correlation coefficients better than 0.94 in comparison with quality ratings made by normal-hearing and hearing-impaired listeners.