Pitch, loudness and frequency selectivity in low-frequency hearing loss

Patients with Ménière's disease and cochlear hydrops show fluctuating low-frequency hearing loss (FLFHL). At present these changes are followed as patients' subjective reports and occasional measurements. Consecutive long-term measurements should provide more comprehensive information on the hearing fluctuations than the occasional audiogram used today and constitute an approach to quantify the fluctuations. Quantifications could potentially be used to define disease subgroups and to evaluate treatments. This thesis aims to introduce 'home audiometry' to monitor hearing function in monaural FLFHL. The approaches contain assessment of other manifestations of the diseases such as frequency selectivity and frequency coding of the auditory system. Long-term monitoring of binaural loudness and pitch matches showed that patients had daily fluctuations not present in normal-hearing subjects. The average day-to-day difference was considered as a measure of disease activity. This measure showed that patients with Ménière's disease had more fluctuations than patients with cochlear hydrops, and that both these groups had had more fluctuations than normal-hearing references. There was no simple relation between the measurements and simultaneous symptom ratings, corroborating the importance of the measurements. It seems possible to separate disease subgroups using long-term measurements of loudness and pitch matches. This could prove to be an essential feature in understanding the diseases and in clinical treatment trials. The deviant pitch matches observed during the long-term measurements suggest changes in inner ear physiology not only related to pure tone hearing. The probable cause is excessive fluid volume in the affected inner ear. Indeed, after pressure exposure in the hypobaric pressure chamber, no average hearing threshold improvements were seen in patients with FLFHL. However, there were improvements in individual subjects regarding speech recognition, outer hair cell function, and frequency selectivity. But deteriorations were also seen, mainly in frequency selectivity. Moreover, after experimentally reducing conflicting frequency information in the affected ear, the pitch matching precision improved to some extent. It is concluded that the long-term measurements provide more and comprehensive information on the hearing fluctuations than the occasional audiograms used today. More advanced measurements can be done as well, which provide more information than the blunt pure tone audiometry. Separate disease subgroups can be identified by quantifications of the fluctuations. The methods can set a new standard for the hearing evaluation of treatment in FLFHL

The impact of tinnitus on cognitive performance in normal-hearing individuals.

The aim of this study was to investigate whether the previously reported differences in cognitive performance as assessed using a Stroop paradigm between individuals with and without tinnitus is present in normal-hearing individuals

Societal costs of hearing disorders: A systematic and critical review of literature.

Objective: The objective of this study was to perform a critical and systematic literature review of studies on societal costs due to hearing disorders. Design: We used predefined search terms and inclusion/exclusion criteria. Systematic searches were conducted in Medline, Cochrane Library, Google Scholar, and other relevant websites. The review included studies written in English or Swedish between 1995 and the end of January 2012. Study sample: We identified four published studies and four reports that met the pre-defined inclusion criteria. Results: Swedish cost studies primarily focused on costs of hearing aids. International studies with a societal perspective used different costing approaches and were limited to specific patient populations. Hearing disorders impact the social welfare system more than the medical care system. Indirect costs account for the major part and direct medical costs for a minor part of the total costs of hearing disorders. Conclusions: There is a need for further studies estimating societal costs for all degrees of hearing disorders, in particular since a large part of the people with hearing disorders are of working age

On the interaction of speakers' voice quality, ambient noise and task complexity with children's listening comprehension and cognition.

Suboptimal listening conditions interfere with listeners' on-line comprehension. A degraded source signal, noise that interferes with sound transmission, and/or listeners' cognitive or linguistic limitations are examples of adverse listening conditions. Few studies have explored the interaction of these factors in pediatric populations. Yet, they represent an increasing challenge in educational settings. We will in the following report on our research and address the effect of adverse listening conditions pertaining to speakers' voices, background noise, and children's cognitive capacity on listening comprehension. Results from our studies clearly indicate that children risk underachieving both in formal assessments and in noisy class-rooms when an examiner or teacher speaks with a hoarse (dysphonic) voice. This seems particularly true when task complexity is low or when a child is approaching her/his limits of mastering a comprehension task

Frequency discrimination in ears with and without contralateral cochlear dead regions

Objective: The purpose of this study was to test the ability to discriminate low-frequency pure-tone stimuli for ears with and without contralateral dead regions, in subjects with bilateral high-frequency hearing loss; we examined associations between hearing loss characteristics and frequency discrimination of low-frequency stimuli in subjects with high-frequency hearing loss. Design: Cochlear dead regions were diagnosed using the TEN-HL test. A frequency discrimination test utilizing an adaptive three-alternative forced choice method provided difference limens for reference frequencies 0.25 kHz and 0.5 kHz. Study sample: Among 105 subjects with bilateral high-frequency hearing loss, unilateral dead regions were found in 15 subjects. These, and an additional 15 matched control subjects without dead regions, were included in the study. Results: Ears with dead regions performed best at the frequency discrimination test. Ears with a contralateral dead region performed significantly better than ears without a contralateral dead region at 0.5 kHz, the reference frequency closest to the mean audiogram cut-off, while the opposite result was obtained at 0.25 kHz. Conclusions: Results may be seen as sign of a contralateral effect of unilateral dead regions on the discrimination of stimuli with frequencies well below the audiogram cut-off in adult subjects with bilateral high-frequency hearing loss

Acceptable noise level: Repeatability with Danish and non-semantic speech materials for adults with normal hearing

Objective: The acceptable noise level (ANL) is used to quantify the amount of background noise that subjects can accept while listening to speech, and is suggested for prediction of individual hearing-aid use. The aim of this study was to assess the repeatability of the ANL measured in normal-hearing subjects using running Danish and non-semantic speech materials as stimuli and modulated speech-spectrum and multi-talker babble noises as competing stimuli. Design: ANL was measured in both ears at two test sessions separated by a period ranging from 12 to 77 days. At each session the measurements at the first and the second ear were separated in time by 15-30 minutes. Bland-Altman plots and calculation of the coefficient of repeatability (CR) were used to estimate the repeatability. Study sample: Thirty nine normal-hearing subjects. Results: The ANL CR was 6.0-8.9 dB for repeated tests separated by about 15-30 minutes and 7.2-10.2 dB for repeated tests separated by 12 days or more. Conclusions: The ANL test has poor repeatability when assessed with Danish and non-semantic speech materials on normal-hearing subjects. The same CR among hearing-impaired subjects would imply too poor repeatability to predict individual patterns of future hearing-aid use

Acceptable noise level with Danish, Swedish, and non-semantic speech materials.

Objective: Acceptable noise level (ANL) has been established as a method to quantify the acceptance of background noise while listening to speech presented at the most comfortable level. The aim of the present study was to generate Danish, Swedish, and a non-semantic version of the ANL test and investigate normal-hearing Danish and Swedish subjects' performance on these tests. Design: ANL was measured using Danish and Swedish running speech with two different noises: Speech-weighted amplitude-modulated noise, and multitalker speech babble. ANL was also measured using the non-semantic international speech test signal (ISTS) as speech signal together with the speech-weighted amplitude-modulated noise. The latter condition was identical in both populations. Study sample: Forty Danish and 40 Swedish normal-hearing subjects. Results: In both populations ANL results were similar to previously reported results from American studies. Generally, significant differences were seen between test conditions using different types of noise within ears in each population. Significant differences were seen for ANL across populations, also when the non-semantic ISTS was used as speech signal. Conclusions: The present findings indicate that there are extrinsic factors, such as instructions, affecting the ANL results. Summario Objetivo: Se ha establecido el Nivel de Ruido Aceptable (ANL) como un método para cuantifi car la aceptación de ruido de fondo mientras se escucha lenguaje presentado al nivel más confortable. El objetivo de este estudio fue generar las versiones sueca, danesa y una no-semántica de la prueba ANL e investigar el desempeño de sujetos normoyentes daneses y suecos en estas pruebas. Diseño: Se midió el ANL utilizando un discurso continuo en danés y sueco con dos diferentes ruidos: ruido con amplitud modulada en el rango del lenguaje y balbuceo de varios hablantes. También se midió el ANL utilizando la prueba internacional no-semántica de señal de lenguaje (ISTS) como la señal lingüística junto con ruido con amplitud modulada en el rango del lenguaje. Esta última condición fue idéntica en ambas poblaciones. Muestra: Cuarenta sujetos daneses y 40 sujetos suecos normoyentes. Resultados: en ambas poblaciones los resultados de ANL fueron muy similares a los reportado previamente en estudios americanos. Generalmente, se vieron diferencias signifi cativas para el ANL entre poblaciones, también cuando el ISTS no semántico fue utilizado como señal lingüística. Conclusiones: Estos hallazgos indican que hay factores extrínsecos tales como las instrucciones, que afectan los resultados de ANL

Functional-structural reorganisation of the neuronal network for auditory perception in subjects with unilateral hearing loss: Review of neuroimaging studies.

This paper aims to provide a review of studies using neuroimaging to measure functional-structural reorganisation of the neuronal network for auditory perception after unilateral hearing loss

A farewell to brake reaction times? Kinematics-dependent brake response in naturalistic rear-end emergencies

Driver braking behavior was analyzed using time-series recordings from naturalistic rear-end conflicts (116 crashes and 241 near-crashes), including events with and without visual distraction among drivers of cars, heavy trucks, and buses. A simple piecewise linear model could be successfully fitted, per event, to the observed driver decelerations, allowing a detailed elucidation of when drivers initiated braking and how they controlled it. Most notably, it was found that, across vehicle types, driver braking behavior was strongly dependent on the urgency of the given rear-end scenario’s kinematics, quantified in terms of visual looming of the lead vehicle on the driver’s retina. In contrast with previous suggestions of brake reaction times (BRTs) of 1.5 s or more after onset of an unexpected hazard (e.g., brake light onset), it was found here that braking could be described as typically starting less than a second after the kinematic urgency reached certain threshold levels, with even faster reactions at higher urgencies. The rate at which drivers then increased their deceleration (towards a maximum) was also highly dependent on urgency. Probability distributions are provided that quantitatively capture these various patterns of kinematics-dependent behavioral response. Possible underlying mechanisms are suggested, including looming response thresholds and neural evidence accumulation. These accounts argue that a naturalistic braking response should not be thought of as a slow reaction to some single, researcher-defined “hazard onset”, but instead as a relatively fast response to the visual looming cues that build up later on in the evolving traffic scenario