Individuals with sensorineural hearing loss (SNHL) are treated with hearing aids and/or a cochlear implant, based on their pure-tone thresholds and speech perception scores. Although these assistive listening devices do help those individuals communicate in quiet surroundings, many still have difficulty understanding speech in noisy environments. The purpose of current study is to compare results of consonant perception when using flat gain (or most comfortable level, MCL) and to see changes in consonant error rate occurred by hearing impairment after applying a frequency specific amplification. Twenty American English speakers with mild-to-moderate SNHL were tested. Isolated English consonant-vowel (CV) syllables, consisting of sixteen consonants followed by the /a/ vowel, were used as stimuli. They were presented monaurally in quiet and at five different signal-to-noise ratios (SNRs) in speech-weighted noise. To compare the consonant error between ‘no NAL-R amplification’ (flat gain) and ‘NAL-R amplification’ conditions, all subjects were tested in the two conditions. When simulating the NAL-R condition, its formula was calculated in two steps for each subject, by obtaining the required gain as a function of frequency. Overall consonant percent errors were decreased with NAL-R correction, compared to the no NAL-R conditions. When we look at the aided audibility and average consonant errors (or scores) after fitting a hearing aid, hearing-impaired (HI) speech perception seems better than before wearing the hearing aid. However, there is a significant difference among consonants: some consonants obtain great benefit from NAL-R and others do not. Also, subjects who have similar pure-tone audibility do not receive the same benefit from the amplification. We conclude that although current amplification fitting methods can offer positive benefit on average to the speech perception of HI listeners, they cannot offer equally positive benefits to every consonant and every HI listener.