Biomedical subjects

Martti J Sorri

Publications and source records attributed to Martti J Sorri.

5 recordsLinked to original sources

PubMed2006

Solutions to electromagnetic interference problems between cochlear implants and GSM phones.

For persons using cochlear implants, electromagnetic compatibility (EMC) problems may sometimes be an obstacle to using digital cellular telephones. This study aimed at exploring the benefit of three new assistive listening device prototypes that eliminate or diminish EMC problems. Ten experienced cochlear implant users listened in quiet to running speech samples and a sentence test on a landline phone, a digital cellular phone with and without three prototypes. The subjects' performance was assessed using a sentence test, a subjective visual analog scale, and by ranking the best and the poorest listening condition. Compared to the other test conditions, listening to a digital cellular phone alone revealed, on average, the poorest sentence recognition scores (29%) and the poorest results in four different subjective judgments (the amount of disturbances, the clarity of the message, the quality of the sound, overall judgment) with all three implant systems tested. The prototypes generally helped the implantees to recognize speech better on the cellular telephone (by 10-21 percent units, on average). Use of assistive listening devices and further development of EMC of both cochlear implant systems and digital cellular phones needs to take place to enable smooth use of digital cellular phones for all implantees.

Adult↗

PubMed2004

Modelling the risk of noise-induced hearing loss among military pilots.

Noise is a significant risk factor in aviation, especially in military aviation. Even though our earlier studies have shown that the risk of noise-induced hearing loss (NIHL) among military pilots is small and the monitoring of their hearing is effective, we still need to develop methods of assessing the risk of NIHL more effectively at both the general and individual levels. In addition, many other risk factors are considered to contribute to the development of hearing impairment. The novel NoiseScan data management system enables assessment of the risk of developing hearing impairment on the basis of known risk factors. This study investigates the risk of hearing impairment among Finnish Air Force pilots using reasonably accurate noise exposure data and other risk factors for hearing impairment. This risk is also compared with that of industrial workers, whose risk followed the ISO 1999 prediction. Hearing among Finnish military pilots turned out to be better than predicted by the ISO 1999 model. The industrial workers had a larger number of risk factors than the pilots. Owing to the small number of risk factors, the hearing of pilots corresponds to approximately the 80th percentile, being 9-13 dB better than the 50th percentile obtained with the industrial population.

Adult↗

PubMed2003

Temporary threshold shift in military pilots measured using conventional and extended high-frequency audiometry after one flight.

Noise of such a high level that it can result in hearing deterioration is an inherent characteristic of military flying. Susceptibility to hearing impairment was studied using 51 Finnish Air Force military personnel as subjects. The test persons flew missions on a British Aerospace Hawk 51 advanced jet trainer, Boeing F-18 Hornet, Mikoyan & Gurevich MiG-21bis and Saab 35 Draken interceptors, and a Valmet Redigo turboprop liaison aircraft. The duration of noise exposure was one flight mission, which varied from 30 to 60 min. Noise doses and levels were measured using a miniature microphone at the inlet of the ear canal, while a second microphone was located at the level of the subject's shoulder. Hearing thresholds were measured before each flight using conventional (0.125-8 kHz) and extended high-frequency (EHF) (8.20 kHz) audiometry. The measurements were repeated as soon as possible after the flight. The study showed that the pre-flight threshold levels of the subjects were good. Both conventional and EHF audiometry revealed statistically significant temporary threshold shifts (TTS) at several frequencies and with all aircraft types involved. The changes were, however, minor. The risk of noise-induced hearing impairment at the studied exposure levels is, in all probability, rather small. The role of extended high-frequency audiometry would be in research, and it might be performed for flying personnel upon entering service and every fifth year thereafter.

Adult↗

PubMed2002

Phoneme recognition and confusions with multichannel cochlear implants: vowels.

The aim of this study was to investigate how postlingually severely or profoundly hearing-impaired adults relearn to recognize vowels after receiving multichannel cochlear implants. Vowel recognition of 19 Finnish-speaking subjects was studied for a minimum of 6 months and a maximum of 24 months using an open-set nonsense-syllable test in a prospective repeated-measure design. The responses were coded for phoneme errors, and 95% confidence intervals for recognition and confusions were calculated. The average vowel recognition was 68% (95% confidence interval = 66-70%) 6 months after switch-on and 80% (95% confidence interval = 78-82%) 24 months after switch-on. The vowels [ae], [u], [i], [o], and [a] were the easiest to recognize, and the vowels [y], [e], and [ø] were the most difficult. In conclusion, adaptation to electrical hearing using a multichannel cochlear implant was achieved well; but for at least 2 years, given two vowels with either F1 or F2 at roughly the some frequencies, confusions were drawn more towards the closest vowel with the next highest F1 or F2.

Acoustic Stimulation↗

PubMed2002

Phoneme recognition and confusions with multichannel cochlear implants: consonants.

The aim of this study was to investigate how postlingually severely or profoundly hearing-impaired adults relearn to recognize consonants after receiving multichannel cochlear implants. Consonant recognition of 19 Finnish-speaking subjects was studied for a minimum of 6 months and a maximum of 24 months using an open-set nonsense-syllable test in a prospective repeated-measure design. Responses were coded for phoneme errors, and proportions of correct responses and 95% confidence intervals were calculated for recognition and confusions. Two years after the switch-on, the mean recognition of consonants was 71% (95% confidence interval = 68-73%). The manner of articulation was easier to classify than the place of articulation, and the consonants [s], [r], [k], [t], [p], [n], and [j] were easier to recognize than [h], [m], [l], and [v]. Adaptation to electrical hearing with a multichannel cochlear implant was successful, but consonants with alveolar, palatal, or velar transitions (high F2) were better recognized than consonants with labial transitions (low F2). The locus of the F2 transitions of the consonants with better recognition was at the frequencies 1.5-2 kHz, whereas the locus of the F2 transitions of the consonants with poorer recognition was at 1.2-1.4 kHz. A tendency to confuse consonants with the closest consonant with higher F2 transition was also noted.

Acoustic Stimulation↗