Development of a Noise Desensitization Program to improve speech perception in noise for adults

Background and Objectives: The present study aimed to develop a noise desensitization program for adults to improve speech-in-noise (SPIN) ability and to derive normative scores for this program in adults. Subjects and Methods: The study was carried out in two phases: 1) the development of a noise desensitization program and 2) The administration of the noise desensitization program to normal-hearing individuals to derive normative cut-off scores. In the initial phase, a material containing lists of 50 activities in the Tamil language to improve SPIN using different signal-to-noise ratios (SNR) from 15 dB SNR to -5 dB SNR, including various types of noise such as environmental noise (fan noise), white noise, single speech babble, multi-speech babble, and cafeteria noise for sentences and words, was developed. These recorded materials were administered to a group of 36 normal-hearing individuals within the age range of 18 to 30 years in the second phase. The mean and the confidence interval for each activity were analyzed to derive cut-off scores. Results The overall mean SPIN scores decreased with the reduction of SNR. The mean SPIN scores were more than 90% for up to + 5 dB SNR and reduced to between 80 and 90% at 0 dB SNR; scores further dropped to between 60 and 80% at -5 dB SNR. The participants reported more difficulty with the cafeteria noise, single-speech babble, and multi-speech babble. At the lowest SNRs of 0 dB and − 5 dB, participants perceived sentences easier than words. Obtained mean SPIN scores for each activity was used as cut off scores. This was used as reference to move to the next activity. Conclusion cut-off scores of activities listed in noise desensitization programs vary depending upon the SNR, type of stimuli, and noise in normal hearing population. This indicates the necessary for activity specific normative cut-off to maintain motivation level of participants.