Adaptive Dynamic Range Optimization (ADRO): A Digital Amplification Strategy for Hearing Aids and Cochlear Implants

Abstract

Adaptive dynamic range optimization (ADRO) is an amplification strategy that uses digital signal processing techniques to improve the audibility, comfort, and intelligibility of sounds for people who use cochlear implants and/or hearing aids. The strategy uses statistical analysis to select the most information-rich section of the input dynamic range in multiplefrequency channels. Fuzzy logic rules control the gain in each frequency channel so that the selected section of the dynamic range is presented at an audible and comfortable level. The ADRO processing thus adaptively optimizes the dynamic range of the signal in multiplefrequency channels. Clinical studies show that ADRO can be fitted easily to all degrees of hearing loss for hearing aids and cochlear implants in a direct and intuitive manner, taking the preferences of the listener into account. The result is high acceptance by new and experienced hearing aid users and strong preferences for ADRO compared with alternative amplification strategies. The ADRO processing is particularly well suited to bimodal and hybrid stimulation which combine electric and acoustic stimulation in opposite ears or in the same ear, respectively.

Evaluation of adaptive dynamic range optimization in adverse listening conditions for cochlear implants

“…The ADRO strategy was initially developed for bimodal listening and has been previously validated for hearing aids and cochlear implants (Blamey, 2005). Studies by James et al (2002) and Dawson et al (2004) concluded that sound quality and speech perception performance were improved using ADRO as compared to fixed channel gains in both adults and children.…”

“…b) Also at School of Behavioral and Brain Sciences, The University of Texas at Dallas,Richardson,Texas 75080. aids (HA) (Blamey et al, 1999;Blamey, 2005). The strategy uses statistical analysis to select the most information-rich section of the input dynamic range in multiple frequency channels, and adaptively adjusts the channel gains based on a set of fuzzy logic rules to optimally place the signal in the users' available hearing range.…”

Effects of Sound-Induced Hearing Loss and Hearing Aids on the Perception of Music

“…Some hearing aids incorporate AGC with multiple time constants [63,64] or time constants that adapt depending on the characteristics of the signal [65]. Such systems are generally designed so that they are slow-acting most of the time.…”

Adjustments of the amplitude mapping function: Sensitivity of cochlear implant users and effects on subjective preference and speech recognition

“…ASC shifts the IIDR up in acoustical level if the estimated background noise level exceeds a certain threshold, and shifts the IIDR down when background noise drops below a lower threshold. ADRO analyzes the average and peak envelope levels and the background noise and adjusts the gain of individual frequency channels to maintain a comfortable loudness perception in each channel (Blamey, 2005;Khing et al, 2013). By adjusting the gain of individual frequency channels, ADRO influences both the selection of the frequency channels for stimulation as well as the stimulation levels with which the selected frequency channels are stimulated.…”