Purpose: The purpose of this study was to assess the changes in gain, aided threshold, word recognition in noise, and sound quality of hearing aids according to the first wearing period of sensorineural hearing loss (SNHL) to determine the rehabilitation goal and effective adjustments of the electroacoustic parameters. Methods: The subjects of this study were 17 SNHL (26 ears) who had no experience in wearing hearing aids, with an average age of 67.5 years, an average pure-tone average of 50.5 dB HL, an average WRS of 68.9%, and a K-IOI-HA (Korean version of International Outcome Inventory for Hearing Aids) score of 25 or higher. The procedure for gain adjustment of the hearing aid was through NAL-NL2 (National Acoustic Laboratories, non-linear version 2) at first adjustment and subjective responses of the subject afterwards. Real-ear insertion gain, aided threshold, WRS in noise, and sound quality evaluation were conducted at week 0 (initial fit), week 2, and week 6 (or final visit). Results: The study showed a higher gain in 55 dB sound pressure level at most frequencies and improved aided thresholds at 1,000 Hz and 2,000 Hz as the wearing period increased. WRS also increased in 10 dB and 5 dB signal-to-noise ratios, and the sharpness, occlusion, and loudness of noise were shown to improve despite the increased gain. Conclusion: Despite the limitation of gain change with the wearing period, the results of this study expect to aid in setting rehabilitation goals according to the wearing period and adjusting electroacoustic parameters.