Biomedical subjects

A Ringdahl

Publications and source records attributed to A Ringdahl.

25 records · Page 2Linked to original sources

PubMed1989

Tinnitus--a study of its prevalence and characteristics.

Three thousand six hundred randomly selected adults in the city of Gothenburg (425,000 inhabitants) stratified by age and gender, were questioned by mail concerning tinnitus. We received 66% useful answers, 14.2% suffered from tinnitus 'often' or 'always'. Tinnitus was more common in males than in females. Tinnitus was much more common in the left than in the right ear. 2.4% of the whole population suffered from the worst severity degree, 'tinnitus plagues me all day'. Tinnitus was clearly more common with hearing loss than with subjectively normal hearing. Sleep disturbances were common and increased with tinnitus severity. A majority of the questioned subjects wanted further examination and treatment.

Adult↗

PubMed1987

Treatment of tinnitus: a controlled comparison of masking and placebo.

Seventeen out of 21 patients with severe tinnitus rated their tinnitus intensity during a baseline period, during treatment with a portable masker, and during a period with a comparable placebo apparatus. Group analyses showed no significant differences between any of the three periods. Seven patients showed significantly reduced tinnitus intensity ratings during the masker period; five of them also did so during the placebo treatment. After each of the treatment periods, the 21 patients answered a questionnaire about specific (tinnitus related) and general beneficial effects experienced during treatment. Specific, but not general, effects were more pronounced during masker than during placebo treatment. In conclusion, masker treatment is not unequivocally superior to placebo; there is some evidence, however, for the placebo treatment effects to be more 'nonspecific' than effects observed during masker treatment.

Adult↗

PubMed1984

Hearing aid prescription rules using insertion gain measurements.

Many of the decisions regarding hearing aid selection and use are based mainly upon clinical impressions. It was therefore decided to investigate whether the old fitting of 25 aided subjects with moderate hearing loss could be improved by using more precise prescription rules and a real ear measuring technique. The rules formulated should give a frequency response of moderate low and pronounced high frequency gain. The application of these rules resulted in improved high frequency gain and better speech discrimination for consonants in noise. As a result of the investigation, the routine procedure of hearing aid fitting has been revised. Earmold modifications of different types should be used more often and real ear canal measurements are recommended for incorporation in the routine examination of hearing aid performance.

Audiometry↗

PubMed1984

The reliability of insertion gain measurements using probe microphones in the ear canal.

Two methods are now available for measuring the insertion gain as a clinical procedure; the ear canal microphone- and the soft probe tube microphone-system. It was decided to investigate some of the variables affecting the reliability of the insertion gain measurements, such as the measurement location and head movement effects, as well as factors related to the presence of the ear canal microphone in the auditory canal. The last variable exhibited significant systematic differences of -2 to 4 dB in the measured insertion gain with the ear canal microphone compared to the measurement obtained with the probe tube microphone. The intrasubject standard deviations were about the same for both methods and less than 4 dB in the frequency range 0.25 to 4.0 kHz. Finally when making clinical hearing aid recommendations using the probe tube microphone technique the errors in one insertion gain measurement are within 95% probability +/- 2 to +/- 8 dB in the frequency range 0.25 to 4.0 kHz.

Adult↗

PubMed1984

Analysis of hearing aid fittings using insertion gain measurements.

Insertion gain was measured in 166 persons after they were fitted with a hearing aid according to the Swedish prescription guidelines. Fitting was considered inadequate (1) when the levels of the long-term RMS speech spectrum were not amplified above the tone threshold at 1.0, 1.5 and 2.0 kHz, or (2) when the speech peak levels did not exceed the tone thresholds at 3.0 and 4.0 kHz. At least 40% of the subjects were found to have inadequate amplification according to these criteria. This number increased further when the measured insertion gain was compared with the gain recommended by other investigators. Our results indicate that real ear insertion gain measurements should be introduced as a routine clinical procedure in the fitting of hearing aids.

Aged↗

PubMedDate not supplied

A simplified real ear technique for verifying the maximum output of a hearing aid.

Real ear SPL (RE/SSPL90) produced by four different hearing aids was compared to the standard SSPL90 measurements for the same hearing aids on a 2-cc coupler. The effects of venting, location, and reliability for RE/SSPL90 were also studied. As expected, the real ear output level was greater than the coupler level. No systematic influence of earmold venting was found. An earmold that occludes an ear canal decreases the output in the high-frequency range so that only a small difference remains between RE/SSPL90 and 2-cc coupler levels above 2000 Hz. The difference seems to be affected slightly by the output impedance of the hearing aid receiver system. Individual variation for the RE/SSPL90 is as much as 10 dB. Finally, the saturated output levels measured were found to be insensitive to changes in actual microphone input levels caused by different procedures for calibrating ambient SPL. The RE/SSPL90 method is easy to use and reliability seems quite adequate for the typical clinical setting.

Adult↗

PubMedDate not supplied

Audiometric earphone discomfort level and hearing aid saturation sound pressure level for a 90 decibel input signal (SSPL90) as measured in the human ear canal.

The acoustical problems involved in matching the saturation sound pressure level for a 90 dB input signal (SSPL90) of a hearing aid to individual discomfort level were investigated. The real ear SPL (RE/SSPL90) produced by a supra-aural earphone used when measuring uncomfortable loudness (UCL), and RE/SSPL90 produced by three different hearing aids at 90 dB SPL input, were measured for nine subjects, using a miniature microphone technique, and compared to the corresponding coupler levels used when matching hearing aid maximum output to UCL. It was found that a hearing aid often gives about 5 dB, and sometimes 10 dB, higher RE/SPLs than the earphone, if the hearing aid output levels, as measured in a 2-cc coupler (IEC126), are equal to the earphone output levels as measured in a 6-cc coupler (NBS9A). It is recommended that a safety margin of at least 5 dB be used in the preliminary fitting when matching hearing aid SSPL90 to the patient's UCL, converted to dB SPL.

Adult↗