Auditory Processing Disorders II: experimental results on APD management with personal FM systems

In a first paper (Mülder, Rogiers and Hoen, the 6~7 volume of Speech and Hearing Review), we have reviewed actual views on Auditory Processing Disorders (APD), their definition, etiology, diagnosis and the actual consensus on APD management strategies. In this second article, we proposed to report on recent experimental work done on the management of APD using environmental modifications via personal frequency modulation (FM) devices. This approach to APD management is based on the assumptions that the attenuation of ambient noise in acoustically challenging situations, such as typical school classrooms can: i) facilitate the processing of sound and in particular speech stimuli by children with APD due to the improved signal-to-noise ratio (SNR) and ii) that the long-term use of such devices may lead to long lasting improvements of listening abilities in APD patients because the improved SNR may facilitate the emergence of new attentional and/or processing strategies that were in worst 《Speech and Hearing Review 8》 Auditory Processing Disorders II: experimental results on APD management with personal FM systems. 129~158 Auditory Processing DisordersII:experimental results on APD management with personal FM systems 128 19. Mayo LH, Florentine M, Buus S. (1997). Age of second-language acquisition and perception of speech in noise. J Speech Lang Hear Res, 40: 686-693. 20. Von Hapsburg D, Champlin CA, Shetty SR. (2004). Reception thresholds for sentences in bilingual (Spanish/English) and monolingual (English) listeners. J Amer Acad Audiol, 15 (1), 88-98. This article appears here with permission from The Hearing Review, Ascend Media, Los Angeles, Calif. The article was translated by Asian Pacific Speech and Hearing Foundation. To obtain the original article (in English), visit the www.hearingreview.com archives. Original citation: Wang BK. Let's Get Real! Understanding the distinctions between aided SRT and WRS. Hearing Review. 2006; 13(2): 22-30. 《Speech and Hearing Review 8》 Let's Get Real! Understanding the Distinctions Between Aided SRT and WRS 220 《Speech and Hearing Review 8-9》 131 including: 1. Direct therapeutic remediation; 2. Environmental modifications and 3. Compensatory strategies. The goal of the present article is to review recent advances and experimental results on the management of APD with environmental modifications with a particular stress on the usage of personal FM systems. The current review will therefore focus on point 2., for a detailed presentation on current definitions, known etiologies, diagnosis methods and other management approaches, readers are referred to Mülder, Rogiers & Hoen, (2007, the 6~7 volume of Speech and Hearing Review), or Moore (2006). Environmental modifications are designed to improve acoustic clarity and enhance learning-listening (Bellis, 2002; 2003). It is universally accepted that all listeners perform better in an environment with acoustic clarity and desirable signal-to-noise ratio (SNR). Primary school children are particularly vulnerable to noise (Shield & Dockrell, 2003) and will experience high levels of noise in classrooms (Blake & Busby, 1994). It was also shown that children will not develop adult-equivalent resistance to noise and reverberation before late teenage years. Before this will be achieved, the younger the children, the more important the difficulties regarding listening in noise and/or in reverberant environments (Stelmachowicz, Hoover, Lewis, Kortekaas & Pittman, 2000; Jamieson, Kranjc, Yu & Hodgetts, 2004). In their review, Picard & Bradley (2001) have estimated that classrooms presented average noise levels of 4 to 37 dB A above the recommended levels and proposed ambient noises guidelines of 40 dB A maximal for 12 years old and older children and reverberation times of 0.5 s. According to these authors, younger students with normal hearing and listening faculties would require levels ranging from 39 dB A (10 – 11 years) to only 28.5 dB A (6 7 years old). Finally they suggested that children with suspected delayed speech processing in noise, such as APD children, 《Speech and Hearing Review 8》 Auditory Processing Disorders II: experimental results on APD management with personal FM systems. 130 SNR situations not achievable by these patients. Results form a first reported study show that children with APD can significantly benefit from the use of FM systems to improve their speech-in-noise comprehension abilities. We also report results from a second study that could evidence long term benefits of the FM treatment on subjective measures, psychoacoustic tests, as well as evidence for improved neural maturation in the auditory pathway as demonstrated by the maturation of auditory event related potential markers over a one-year period. All these results are discussed in the context of current consensus on APD diagnosis and management.