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Biomedical subjects

B Almqvist

Publications and source records attributed to B Almqvist.

5 recordsLinked to original sources
PubMed1992

Recognition of telegraphy signs at different listening levels and frequencies.

The recognition of telegraphy masked by noise at 40 and 80 signs/min telegraphy speed was studied in 10 normal-hearing subjects at different sound pressure levels (25-85 dB SPL in steps of 5 dB) as well as at different test frequencies (2000, 1000, 800, 630, 500 and 250 Hz). The ability to recognize the signs varied with varying SPL. Recognition for most of the subjects was best at an SPL close to 70 dB. All subjects improved their recognition as the frequency was lowered to 500 Hz, some even at 250 Hz. These facts should be taken into consideration when training telegraphy operators as well as in the construction of radio receivers to permit listening at low frequencies. Furthermore, the critical ratio was calculated at the different test frequencies.

Acoustics↗
PubMed1991

Recognition of telegraphy disturbed by noise at different S/N-ratios and different telegraphy speeds. A comparison to short-tone audiometry.

The ability to recognize telegraphy at different S/N ratios and telegraphy speeds was compared for 10 normal-hearing men trained in detecting telegraphy. The ability to recognize telegraphy disturbed by noise decreased with increasing telegraphy speed and reduced S/N ratio. The recognition of telegraphy disturbed by noise seems to follow the relations known from experiments with short-tone audiometry.

Adult↗
PubMed1989

Phase audiometry--a rapid method for detecting cerebello-pontine angle tumours?

Four groups of subjects have been investigated, using a manual phase audiometer. Group 1 consisted of 20 normal-hearing subjects. Group 2 of 22 subjects with unilateral or asymmetric cochlear hearing loss. Group 3 of 14 subjects with surgically verified CPA tumours, and Group 4 of 15 subjects with unilateral conductive impairment. In this report we suggest an upper borderline value for detecting interaural time differences of 120 microseconds. If the subject is able to detect only a value exceeding 120 microseconds, there is likely to be a retrocochlear lesion.

Adolescent↗
PubMed1987

Effects of low-frequency components and analog filtering on auditory brainstem responses. A comparison of analog and digital filtering.

Analog and digital filtering of ABR (Auditory Brainstem Response) is compared for 20 adults with normal hearing. The result shows that the shape of the ABR is changed by the non-linear phase function of the analog filter (350-1,700 Hz). Peaks IV and V are particularly affected. The result also shows that if peaks IV and V are to be identified with certainty it is sometimes necessary to raise the lower band limit of the filter. This is because the low-frequency part of the ABR interferes with peaks IV and V. The latencies of peaks I to V obtained from ABRs after digital and analog filtering have been compared. This showed small but significant differences.

Adult↗