Relation Between Listening Effort and Speech Intelligibility in Noise

Abstract

The adaptive procedure for rating subjective listening effort yields information beyond using speech intelligibility to estimate hearing difficulties and to evaluate hearing aids.

Benefit of binaural listening as revealed by speech intelligibility and listening effort

“…The sentence and masker were presented in a loop until the subjects made their assessment of "How much effort do you have to spend to understand the speech?" The response scale was the same as used in previous studies (Rennies et al, 2014a;Schepker et al, 2016;Krueger et al, 2017a;Krueger et al, 2017b) and consisted of 13 listening effort ratings with the seven named categories "no effort" (1 effort scaling categorical unit, ESCU), "very little effort" (3 ESCU), "little effort" (5 ESCU), "moderate effort" (7 ESCU), "considerable effort" (9 ESCU), "very high effort" (11 ESCU), and "extreme effort" (13 ESCU), as well as of six unnamed categories in-between. In addition, a 14th category named "only noise" was provided for conditions in which subjects could not hear any target speech (and hence an assessment of listening effort would not be meaningful, see Krueger et al, 2017a).…”

“…Ratings of only noise were excluded from the fitting. The same model function as used by Krueger et al (2017a) and Krueger et al (2017b) was used, which consists of two straight lines that intersect at 7 ESCU (i.e., the mid-point of the listening effort scale). The transition between the two lines is smoothed by a B ezier function.…”

“…The present study employed one particular method for assessing listening effort-categorical scaling as used in several previous studies (e.g., Krueger et al, 2017a;Krueger et al, 2017b;Luts et al, 2010;Rennies et al, 2014a;Schepker et al, 2016)-and focused on one specific set of stimuli and conditions. Although this approach revealed some novel insights into binaural speech perception, the most complete understanding of this topic would be based on additional work providing converging evidence for the present findings and extending them to other types of stimuli and listening situations.…”

“…Listening effort can be defined as "the deliberate allocation of mental resources to overcome obstacles in goal pursuit when carrying out a listening task" (Pichora-Fuller et al, 2016) and has been the subject of an increasing number of studies in recent years, although these studies differ somewhat in terminology (e.g., "listening effort," "listening difficulty," "ease of listening"). Several studies have employed scaling procedures to directly assess perceived listening effort (e.g., Morimoto et al, 2004;Luts et al, 2010;Sato et al, 2012;Rennies et al, 2014a;Schepker et al, 2016;Krueger et al, 2017a;Krueger et al, 2017b). Other studies used a dual-task approach in which an increase in effort was related to the decrease in performance on a secondary task that occurred when the difficulty of a primary listening task was increased (e.g., Sarampalis et al, 2009;Gosselin and Gagne, 2010;Houben et al, 2013;Johnson et al, 2015;Xia et al, 2015).…”

“…The main reason for the increasing interest in the assessment of listening effort is that it may add information relevant for speech perception in realistic communication situations beyond that which is measurable with speech intelligibility. For example, it has been shown that listening effort ratings can be used to discriminate among listening conditions in which speech intelligibility is at or close to ceiling (e.g., Houben et al, 2013;Rennies et al, 2014a;Schepker et al, 2016;Krueger et al, 2017b), but which still differ considerably in how challenging it is for the listener to follow the target talker. This observation is particularly relevant for certain practical applications because many everyday communication situations are characterized by positive or only marginally negative SNRs (Smeds et al, 2015) where speech intelligibility typically is very high (at least for normal-hearing listeners).…”