Background noise can have a detrimental effect on the intelligibility of speech for all listeners. However, for individuals with a cochlear hearing loss, these effects can have even greater consequence. As persons with cochlear damage are unable to make use of the "dips" and spatial separation of noise, they may require a greater speech to noise ratio than a person with a normal, non-impaired cochlea. Professionals in the field of audiology attempt to assist an individual compensate for their hearing loss, and the difficulties associated with it, by providing the appropriate amplification, usually in the form of a hearing aid. A current methodology for manipulating the signal-to-noise (S/N) ratio that hearing aid manufacturers have developed is "noise reduction". The purpose of this study was to determine if there was a significant change in S/N ratio due to the internal noise reduction circuitry in four sample digital hearing aids, across five environmental noise conditions, and across the four sample digital hearing aids in conjunction with the five environmental noise conditions. Statistical analysis showed that for the sample the change in S/N ratio was significant at the 0.05 level of significance as an effect of the hearing aids. The analysis showed that for the sample the change in S/N ratio was not significant at the 0.05 level of significance across the five environmental noise conditions. The analysis showed that for the sample the change in S/N ratio was not significant at the 0.05 level of significance across the interaction of the four sample digital hearing aids in conjunction with the five environmental noise conditions.