Biomedical subjects

Rudolf Haeusler

Publications and source records attributed to Rudolf Haeusler.

3 recordsLinked to original sources

PubMed2005

Minimum audible angle, just noticeable interaural differences and speech intelligibility with bilateral cochlear implants using clinical speech processors.

Sound localization and speech intelligibility were assessed in 5 patients implanted bilaterally with Medel C40+ or Medel C40 cochlear implant (CI) systems. The minimum audible angle (MAA) around the head in the horizontal plane was assessed in patients with bilateral CI using white noise bursts of 1000 ms duration presented from a loudspeaker mounted on a rotating boom and compared with the MAA of age-matched normal hearing controls. Spatial discrimination was found to be good in front and in the back of the head with near-normal MAA values (patients: 3-8 degrees , controls: 1-4 degrees ). In contrast, poor performance on the sides was found (patients: 30 to over 45 degrees , controls 7-10 degrees ). Bilateral CI significantly improved spatial discrimination in front for all patients, when compared with the use of either CI alone. Just noticeable differences (JNDs) in interaural intensity and time were assessed using white noise bursts (1000 ms duration; 50 ms linear ramp). In addition, interaural time JNDs were assessed using click trains (800 ms duration, 40 mus clicks, 50 Hz) and noise bursts in which either only the envelope or only the fine structure was shifted in time. In comparison with normal hearing controls, patients with bilateral CI showed near-normal interaural intensity JNDs but substantially poorer interaural time JNDs depending on the type of stimulus. In contrast to envelope onset/offset cues, interaural fine structure time differences were not perceived by the patients using CI systems employing the continuous interleaved sampling strategy without synchronization between their pulse stimulation times. Speech intelligibility in quiet and CCITT noise from the side (+/-90 degrees ) was assessed using the German HSM sentence test and was significantly better when using bilateral CI in comparison with either unilateral CI, mainly due to a head shadow effect. These favorable results are in agreement with the patients' subjective experiences assessed with a questionnaire and support the use of bilateral CI.

Adolescent↗

PubMed2005

An international otology database.

There are many reports in the literature on the outcome of ear surgery. However, it is difficult to make comparisons from these reports because of a lack of uniformity in the way in which outcomes are reported. At the same time, the general public expects doctors to provide them with information regarding the benefits and risks of surgery. Many ear surgeons will not be able to provide this information because few have an up-to-date database. A group of otologists in Europe has attempted to establish a common otology database. The aim is to create a framework whereby surgeons in Europe can contribute to a common ear database using a web-based system. The proposed methodology involves two levels of data entry. Level 1 is a minimal database where the main outcomes are included. Level 2 is a comprehensive database where detailed information on pathologies, risk factors, and surgical procedures is also recorded. As both databases share the same core data, clinicians using database 1 can still compare their outcomes with those using database 2. Clinicians will be able to input and retrieve ear data onto or from the web-based database. There has already been an international consensus on the content of the common ear database. The website address is www.ear-audit.net. The international project has now been in operation for more than 6 months, and Ear UK has already given its endorsement. The founder members include 27 otologists from 12 European countries. The cumulative outcome from this group of surgeons will be used as the benchmark for the purpose of comparative audit. These benchmark sites will be subjected to regular external validation. The web-based system is interactive and gives instant feedback to individual surgeons who wish to compare their results to the benchmark. Therefore, it can be a good learning tool for trainees or less experienced surgeons. The common data entry system also provides an opportunity for clinicians to collaborate in clinical research.

Databases, Factual↗

PubMed2002

Changes of voice and articulation in children with cochlear implants.

OBJECTIVE: The different speech sounds are formed by the primary voice signal and by the shape of the articulation tract. With this mechanism, specific overtones, the formants, are generated for each vowel. The objective of this study was to investigate the fundamental frequency (F0) of the voice signal and the first three formants (F1-F3) as a parameter of the articulation in prelingually deafened children at different timepoints after cochlear implantation (CI) compared with children with normal speech development. METHODS: Using the Kay CSL 4300B, the fundamental frequency and the formants F1-F3 of the Swiss-German vowel /a/ were investigated at different timepoints after CI in 20 prelingually deafened children aged 3.8-10.2 years by means of spectrographic and linear predictive coding (LPC) analysis. RESULTS: Children who had been operated before their fourth birthday showed no significant deviation in their fundamental frequency from age- and sex-matched peers, whereas a significant difference was documented in children who were older at the time of implantation. The first formant was very stable in every child and showed only discrete deviations from the normal range. The second and third formants, however, developed a broader scatter, but there was no systematic deviation of these formants to higher or lower values. The F1:F2 ratio was normal in children who were implanted at the age of up to 4 years and more centralized in children who were older at the time of implantation, as is known from the hearing impaired. CONCLUSIONS: Our results indicate that prelingually deaf children who receive a cochlear implant before their fourth birthday attain a better acoustic control over their speech, normalizing their fundamental frequencies and improving their articulatory skills.

Articulation Disorders↗