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Binaural and spatial hearing
Published in Stanley A. Gelfand, Hearing, 2017
We may now define the MLD as the difference (advantage) in masked threshold between dichotically presented stimuli and signals that are presented monotically (or diotically). It is not surprising to find that the MLD is also referred to as binaural unmasking, binaural release from masking, or the binaural masking level difference (BMLD). We shall express the magnitude of the MLD as the difference in decibels between a particular dichotic arrangement and either the SmNm or SoNo conditions. Other MLD conditions are discussed below.
Effect of gap detection threshold and localisation acuity on spatial release from masking in older adults*
Published in International Journal of Audiology, 2022
Nirmal Kumar Srinivasan, Alexis Staudenmeier, Kelli Clark
The process of understanding target speech in the presence of masking speech partially involves separating out and attending to the acoustic information of the target speech while ignoring the acoustic information of the masking speech. Target speech and masking speech can be segregated based on factors such as the locations of the target and maskers in the environment, differences in fundamental frequencies between the target and maskers, interaural time differences (ITDs), interaural level differences (ILDs), or differences in contextual information between the target and maskers (Bronkhorst 2015). Spatial release from masking (SRM) is the reduction in target identification thresholds when the maskers are spatially separated from the target (Best et al. 2006; Carhart, Tillman, and Greetis 1969; Gallun, Mason, and Kidd 2005; Helfer, Chevalier, and Freyman 2010; Marrone, Mason, and Kidd 2008b). Results from recent speech masking studies confirmed that an individual’s ability to obtain a better identification threshold when the target and maskers are spatially separated is driven by a combination of better-ear listening, binaural unmasking, and perceived location of the target and the maskers (Arbogast, Mason, and Kidd 2002; Best et al. 2006; Freyman et al. 1999; Marrone, Mason, and Kidd 2008a). Better-ear listening is an auditory phenomenon created by the head shadow effect wherein the listener uses the interaural level differences between the two ears to better understand speech. Binaural unmasking is the increased ability of the listeners to better understand speech in the presence of noise when there is an interaural time difference between the signals at the ears (Culling, 2007; Durlach 1963).
Development of the Turkish hearing in noise test for children
Published in Cochlear Implants International, 2023
Ecem Kartal Özcan, Şule Çekiç, Gonca Sennaroglu, Sigfrid D. Soli
Many studies have been conducted on binaural hearing, where different dimensions of binaural unmasking were tested in different populations. Generally binaural hearing abilities improve at a very young age (Van Deun et al., 2009). In fact, one study indicated that the mechanisms for speech source detection are developed in early childhood (Garadat and Litovsky, 2007). However, this may not be valid for the mechanisms of speech reception (Garadat and Litovsky, 2007). This shows that the underlying mechanisms of speech reception and detection may be different; hence, their developmental patterns are also different. On the contrary, several researchers have shown that the SRM advantage in young children is not as much as that in adults (Nozza et al., 1988; Stuart, 2005). Similarly, in our study, none of the 6-, 8-, and 10-year-old children could reach the adult-like SRM advantage score. However, this finding was different for the 12-year age group, as in other HINT-C adaptation studies. Moreover, the developmental effect for SRM was nonlinear, unlike that for speech reception, most probably because of the different mechanisms underlying the two abilities. For example, the 6-year-old group's SRM advantage scores were better than 8 and 10-year-olds. Indeed, the potential effects of the type of target acoustic signal (pure tone or speech), frequency content of the signals, location of the target signal and noise source, acoustic characteristics of the test room, presence of reverberation, reverberation time, and response types (Litovsky, 2005; Lynn et al., 1981; Myhrum et al., 2016), working memory characteristics and concentration on the testing SRM ability should not be underestimated. We think that the differences related to SRM can be explained by these factors, in the literature, including our study.
Binaural summation, binaural unmasking and fluctuating masker benefit in bimodal and bilateral adult cochlear implant users
Published in Cochlear Implants International, 2021
Feike de Graaff, Robert H. Eikelboom, Cathy Sucher, Sophia E. Kramer, Cas Smits
Binaural unmasking refers to the improvement in speech recognition in noise due to inter-aural time differences (ITDs). It is determined by comparing diotic and dichotic (antiphasic) speech recognition. Dichotic speech recognition is obtained with identical noise signals in both ears, while the speech signal presented to one of the two ears is phase inverted (SπN0). The binaural auditory system uses the interaural speech cues, reflected by the difference between the monaural signals, to improve speech recognition scores in noisy conditions.