| Summary: | 碩士 === 國立台北護理學院 === 聽語障礙科學研究所 === 98 === Prescribed target is regarded as the starting point of hearing aid fitting. NAL and DSL are two generic fitting methods which have been used in hearing aid fitting and verification worldwide. The purpose of this study was to determine the relationship of prescribed targets, wearers’ preferred listening level and acceptance between NAL-NL1 and DSL v 5.0 adult version.
Sixteen current hearing aid wearers with mild to severe sensorineural hearing loss were recruited. Ten of them are binaural wearers and six are monaural wearers. Their own hearing aids were used for the study. All hearing aids have been verified by NAL-NL1 before the study. Real Ear Mesurement (REM) was conducted to collect Real Ear Aided Response (REAR). Three different stimuli (55, 70 dB SPL speech and 85 dB SPL pure tone) were used for the REM. 70 dB SPL recorded speech stimuli was used for the Preferred Listening Level test. Then the hearing aids were programmed and verified with DSL v5.0. REAR of targets and of PLL for both NAL-NL1 and DSL v5.0 were recorded. Finally a Fitting Methold Preferrence questionnaire was used to determine wearer’s acceptance of DSL v5.0. Paired t-test was used for the target comparison. Linear regression and Paired t-test were used for the comparison of recommended listening level and preferred listening level.
For 55 dB SPL speech stimulus, NAL-NL1 REAR targets at 1000 to 3000 Hz were greater than those of DSL v50. For 70 dB SPL speeh stimulus, NAL-NL1 REAR targets at low and high frequencies were less than those of DSL v5.0, but NAL-NL1 REAR targets were more than DSL v5.0 REAR at mid frequencies. For RESR, all frequencies except for 4000 Hz，NAL-NL1 prescribed less RESR. Linear regression of the recommended listening level (RLL) and preferred listening level (PLL) suggested subjects’ PLLs were less than the recommended. The paired t-test result suggested there was significant difference (*p<0.0001) between NAL-NL1 RLL and subjects’ PLL, but no significant difference (p=0.0515) between DSL v5.0 RLL and subjects’ PLL. The differences were -4.308 and -1.381 dB respectively. Ten out of sixteen preferred DSL v5.0 in daily use. Main reason for the preference of DSL v5.0 was that DSL v5.0 provided better clarity, more awareance of soft sounds and better understanding in noisy environment.
Based on this study, subjects’ preferred listening level was more close to the recommended listening level of DSL v5.0. More subjects preferred DSL v5.0 than NAL-NL1 in daily use. It is suggested that DSL v5.0 fitting method can be used in adults’ hearing aid fitting and verification procedure.
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