Search PubMed⌕ Search

Biomedical subjects

J Kiessling

Publications and source records attributed to J Kiessling.

At least 19 recordsLinked to original sources
PubMed2006

[New aspects of hearing aid fitting in noise-induced hearing loss].

In the past hearing aid fitting frequently turned out to be a problem in patients with noise-induced hearing loss. Selective amplification in the high frequency range and at the same time natural sound and appropriate wearing comfort (open fitting) could not be achieved in numerous cases. Today these problems can be tackled by modern hearing aid technology providing us with efficient feedback suppression algorithms making open fittings possible for many more patients. This development is particularly beneficial for patients with noise-induced hearing loss. Unfortunately, open fitting is in opposition to wearing hearing aids at noisy workplaces. Tight fittings, however, can be used at work if a special listening program for noisy conditions is available. This dilemma is discussed and possible solutions are pointed out.

Germany↗
PubMed2006

Rickettsia spp. in Ixodes ricinus ticks in Bavaria, Germany.

This study aims to provide information on the occurrence of spotted fever rickettsiae in Ixodes ricinus ticks in southern Germany. A total of 2,141 I. ricinus ticks was collected in Bavaria. Pools of 5-10 ticks were studied by a PCR targeting the rickettsial citrate synthase gene gltA. The average prevalence rate was 12% (257 of 2,141). Sequencing data exclusively identified Rickettsia helvetica DNA. Results and other data demonstrate the possible role of R. helvetica in I. ricinus as a source of human infections in southern Germany.

Animals↗
PubMed2004

[Speech perception. The basis for speech audiometry examinations].

Speech recognition measurements are widely used in clinical applications. Usually, either a speech recognition threshold is determined, being defined as the speech level or signal-to-noise ratio that enables the patient to understand 50% of the target words or target sentences. In other cases, a discrimination curve, describing speech recognition as function of the presentation level, is recorded. For the interpretation of these findings, it is important to keep in mind that speech perception is affected by many interacting sensory, perceptual and cognitive processes.Here, our current knowledge of these processes is outlined and theories that model speech perception in general are briefly reviewed.

Audiometry, Speech↗
PubMed2002

Observation of polarity induction by cytochemical localization of phenylalkylamine-binding sites in regenerating protoplasts of the moss Physcomitrella patens.

Different external (e.g., light) and internal (e.g., auxin and calcium gradients) factors control differentiation of the moss protonema. The present investigations demonstrate that exogenously applied auxin, the pharmacological blockade of auxin efflux by naphthylphthalamic acid, and treatment with (-)bepridil, a calcium channel antagonist, inhibit protoplast division without affecting protoplast viability in the moss Physcomitrella patens. A fluorescently labelled phenylalkylamine (DM-Bodipy PAA), another calcium channel antagonist, was used as a probe for in vivo labelling of phenylalkylamine(PAA)-binding sites. The specificity of this binding was demonstrated by competition with (-)bepridil. Confocal laser scanning microscopy visualized PAA-binding sites on the plasma membrane and along the nuclear membrane as uniformly distributed clusters. During asymmetric division of P. patens protoplasts, however, fluorescence labelling particularly increases at the membrane invagination and later along the plate separating the new cells. Intracellular localization of PAA-binding sites, probably at the membranes of vesicles and vacuoles, significantly increases in the smaller daughter cell, destined to later form a polar outgrowth, the first chloronema cell. Thus, a system was established to visualize early events in P. patens protoplast polarization at the subcellular level.

Aniline Compounds↗
PubMed2001

Hearing aid fitting procedures--state-of-the-art and current issues.

The increasing degree of sophistication in hearing aid technology calls for appropriate fitting strategies, as otherwise hearing aid users cannot receive the full benefit from the most modern technological achievements. This paper describes the state of the art in hearing aid fitting procedures and offers a look into possible future developments. Currently, threshold-based fitting formula compete with loudness- and sound-based fitting procedures. Whereas threshold-based approaches are straightforward and timesaving, they do not consider loudness growth and the sound preferences of the listener. On the other hand, loudness- and sound-based procedures do take these aspects into account, but they are time consuming and it is not yet proven that they provide higher benefit for the end user. This may be due to the fact that either there is actually no extra benefit or more likely that the evaluation tools or study designs have to be improved. Concerns about how to fit more advanced future hearing instruments seem to be inappropriate, as an analysis of possible future signal processing algorithms shows that they probably do not need extra fitting to the individual hearing impairment but rather need optimization according to the acoustical environment.

Hearing Aids↗
PubMed2001

A fitting strategy for digital hearing aids based on loudness and sound quality.

In order to find an adequate fitting strategy for digital compression hearing aids a combination of two interactive fitting strategies was developed, one of these based on frequency specifice loudness (ScalAdapt) and the other based on overall loudness and on sound quality (Cambridge Procedure). This new fitting strategy was tested against the sound and overall loudness based strategy and against a prescriptive fitting strategy in a 2-weeks field test with questionnaires and in laboratory measurements, subjectively as well as objectively. With six sensorineural hearing impaired participants no straightforward results were achieved. Additionally, the different testing procedures indicate (in tendency) different fitting strategies to be superior. More subjects will have to be tested and innovative evaluation methods have to be considered.

Acoustic Stimulation↗
PubMed2001

Multi-microphone technology for severe-to-profound hearing loss.

In this study the potential benefit of hearing instruments with multi-microphone technology was investigated in laboratory and in field tests for users with severe-to-profound hearing loss. Twenty-one experienced hearing aid users were fitted with high-power multi-microphone hearing instruments (Phonak PowerZoom P4 AZ). The following evaluations were performed: (i) adaptive speech test (SRT for HSM sentence test) in quiet and in noise with their own instrument and the test instrument in the omnidirectional (basic program) and directional mode (party noise profound+zoom algorithm). (ii) Paired comparisons of loudness, sound quality and speech intelligibility for both the omni and zoom program. (iii) Questionnaires on satisfaction and self-assessment of communication in different listening conditions (Oldenburg Inventory). Only 10 subjects achieved 50% correct (SRT) on the sentence test in noise (speech 0 degrees/noise 180 degrees) with both their own instrument and the test instrument in the omnidirectional mode. However, 15 subjects succeeded in the SRT measurement in the directional mode. The average SRT improvement of the directional over the omnidirectional mode was 13.7 dB. Loudness was judged 'medium loud' for both listening programs. Sound quality and intelligibility were rated significantly better for the zoom program. Compared to their own instrument users' satisfaction with the test instrument was significantly higher, especially in noisy listening situations.

Acoustic Stimulation↗
PubMed2001

Benefit of a digital feedback suppression system for acoustical telephone communication.

Because hearing instruments have traditionally performed poorly during acoustical telephone use, the benefit of using a Digital Feedback Suppression (DFS) system for acoustical telephone communication was evaluated. For this purpose a special speech test based on the method and material of the Oldenburg Sentence Test was developed, presenting the speech signal via a telephone receiver. The correct coupling of the receiver and the hearing aid was monitored by means of a probe microphone. The word score was determined for two different settings of the hearing aid: (1) DFS activated (2) DFS deactivated. The difference in word score between these two conditions is an indication of the benefit provided by the DFS system. For almost all subjects, speech recognition at the telephone could be improved using the DFS system. This is a significant contribution in increasing end-user overall satisfaction with hearing aids.

Acoustic Stimulation↗
PubMed2001

Comparison of two digital hearing instrument fitting strategies.

Two different hearing instrument fitting strategies were compared in the laboratory and in a field test with regard to the benefit for hearing aid users and their satisfaction with the fitting. DSL [input/output (i/o)] fittings based on hearing threshold and uncomfortable levels for the subject were evaluated vs a prescriptive fitting method based on unaided loudness scaling. Twenty-one subjects were fitted diotically with both fitting strategies implemented in a digital hearing instrument (Siemens Prisma). The patients tested both fitting strategies sequentially in a 4 + 4-week field trial using a crossover study design. Speech recognition threshold measurements, sound quality ratings and paired comparisons of sound quality were performed for all conditions (unaided, DSL[i/o] fitting and loudness-based fitting). In addition, subjective benefit and preference were assessed with questionnaires. Speech audiometry did not reveal significant differences between the two fittings. DSL[i/o] fittings showed superior results in most sound quality tests and in the self-assessment of communication abilities while the loudness-based approach was slightly preferred in noisy environments. The results seemed to be influenced by the higher gain predicted by DSL[i/o]. This study provides no evidence that effort spent on loudness scaling leads to improved fitting results.

Audiometry, Speech↗
PubMed2000

Visualization of a cytoskeleton-like FtsZ network in chloroplasts.

It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton. Recently, this belief was questioned by the finding that the bacterial cell division protein FtsZ resembles tubulin in sequence and structure and, thus, may be the progenitor of this major eukaryotic cytoskeletal element. Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure. Both their encoded proteins are imported into plastids and there, like in bacteria, they act on the division process in a dose-dependent manner. Whereas in bacteria FtsZ only transiently polymerizes to a ring-like structure, in chloroplasts we identified persistent, highly organized filamentous scaffolds that are most likely involved in the maintenance of plastid integrity and in plastid division. As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term "plastoskeleton" for this newly described subcellular structure.

Arabidopsis↗
PubMed1999

[The usefulness of today's hearing aids--possibilities and limitations].

Some ten to twelve million people in Germany are estimated to need hearing aids. Many of the hard of hearing suffer from inner ear deafness with hair cell dysfunction, and not only hear sounds at too low a level of intensity, but also distorted and unintelligible. Modern special digital hearing aids are able, by appropriate amplification of certain frequencies or frequency bands or, e.g. through the use of directional microphones, to improve discrimination of speech from surrounding noise. In patients with mild hearing losses in particular, the use of bilateral hearing aids is recommended to improve speech recognition. Attention is drawn to the importance of individual counselling and the testing of the hearing aids by the patient.

Hearing Aids↗
PubMed1997

Clinical evaluation of three different loudness scaling protocols.

Loudness scaling has recently attracted much attention as a valuable clinical tool for acquiring reliable knowledge about loudness perception. This information can be used for diagnostic and rehabilitative purposes. In this study a loudness scaling module implemented in a new PC-based audiological test system was comprehensively tested. The system has proven to be a reliable and useful tool in a clinical environment. The described 'Default' loudness scaling protocol seems to represent an appropriate set of parameters. A comparison between this protocol and two other protocols available for clinical use indicates that the 'Default' protocol presents the same consistency of subject response as the 'IHAFF' protocol, and a better consistency than the 'LGOB' protocol. Regarding time consumption, the 'Default' protocol is superior to the 'IHAFF' protocol and comparable to the 'LGOB' protocol.

Audiometry, Pure-Tone↗
PubMed1996

[Recruitment detection--a comparison of category loudness scaling and classical supra-threshold audiometry].

BACKGROUND: The assessment and localization of hearing impairments require reliable and valid recruitment indicators. Although many diagnostic tests are available, which of these tests are most important is still the subject of controversy. METHOD: To compare the efficacy of various diagnostic audiometric tests, 51 subjects with monaural sensorineural hearing loss were submitted to the following tests at 500 and 2000 Hz: category loudness scaling of narrowband noise bursts, alternate binaural loudness balance (ABLB), intensity difference limen test, SISI test, fixed frequency Békésy audiometry, and contralateral determination of the acoustic reflex threshold for pure tones. RESULTS: Using the findings of the ABLB test as reference, the results of the present study revealed that category loudness scaling and acoustic reflex audiometry are reliable quantitative recruitment indicators. This holds for the intensity difference limen test to a lesser extend as well. However, the recruitment selectivity of the SISI test and Békésy audiometry turned out to be considerably poorer. CONCLUSIONS: Category loudness scaling has proven to be a valuable element in the conventional recruitment test battery particularly for patients with symmetrical hearing loss. Therefore, category loudness scaling, ABLB test (when feasible), acoustic reflex measurement, and to a lesser extend the intensity difference limen test should be given the highest priority when selecting appropriate diagnostic audiometric tests. The efficacy of the SISI test and Békésy audiometry should be comprehensively reevaluated on the basis of expanded data. Until such material is available and a final judgement of the clinical value is possible, both these tests should be used and interpreted carefully.

Audiometry, Pure-Tone↗