Effects of age and hearing loss on concurrent vowel identification

Abstract

Differences in formant frequencies and fundamental frequencies (F0) are important cues for segregating and identifying two simultaneous vowels. This study assessed age- and hearing-loss-related changes in the use of these cues for recognition of one or both vowels in a pair and determined differences related to vowel identity and specific vowel pairings. Younger adults with normal hearing, older adults with normal hearing, and older adults with hearing loss listened to different-vowel and identical-vowel pairs that varied in F0 differences. Identification of both vowels as a function of F0 difference revealed that increased age affects the use of F0 and formant difference cues for different-vowel pairs. Hearing loss further reduced the use of these cues, which was not attributable to lower vowel sensation levels. High scores for one vowel in the pair and no effect of F0 differences suggested that F0 cues are important only for identifying both vowels. In contrast to mean scores, widely varying differences in effects of F0 cues, age, and hearing loss were observed for particular vowels and vowel pairings. These variations in identification of vowel pairs were not explained by acoustical models based on the location and level of formants within the two vowels.

Brainstem correlates of concurrent speech identification in adverse listening conditions

“…The effects of F0 on concurrent vowel identification were comparable and consistent with previous data (Arehart et al, 1997; Bidelman and Yellamsetty, 2017; Chintanpalli and Heinz, 2013; Chintanpalli et al, 2016; Reinke et al, 2003; Yellamsetty and Bidelman, 2018), listeners were better at perceptually identifying speech mixtures when vowels contained pitch cues. However, we also showed that this perceptual F0-benefit was larger for the clean than the noise degraded (+5 dB SNR) conditions.…”

“…A handful of studies have shown certain vowels dominate perception among different vowel pair combinations (Assmann and Summerfield 1990; Assmann and Summerfield, 2004; Chintanpalli et al, 2014; Chintanpalli and Heinz, 2013; Chintanpalli et al, 2016; Meddis and Hewitt, 1992a), reminiscent of our vowel dominancy data (Fig. 6).…”

“…The segregation of a complex auditory mixture is thought to involve a multistage hierarchy of processing, whereby initial pre-attentive processes that partition the sound waveform into distinct acoustic features (e.g., pitch, harmonicity) are followed by later, post-perceptual principles (Koffka, 1935) (e.g., grouping by physical similarity, temporal proximity, good continuity (Bregman, 1990) and phonetic template matching (Alain et al, 2005a; Meddis and Hewitt, 1992). Psychophysical research from the past several decades confirms that human listeners exploit fundamental frequency (F0) differences (i.e., pitch) to segregate concurrent speech (Arehart et al, 1997; Assmann and Summerfield, 1989; Assmann and Summerfield, 1990; Assmann and Summerfield, 1994; Chintanpalli et al, 2016; de Cheveigne et al, 1997). For example, when two steady-state (time-invariant) synthetic vowels are presented simultaneously to the same ear, listeners’ identification accuracy increases when a difference of four semitones(STs) is introduced between vowel F0s (Assmann and Summerfield, 1989; Assmann and Summerfield, 1990; Assmann and Summerfield, 1994; Culling, 1990; McKeown, 1992; Scheffers, 1983; Zwicker, 1984).…”

“…For example, when two steady-state (time-invariant) synthetic vowels are presented simultaneously to the same ear, listeners’ identification accuracy increases when a difference of four semitones(STs) is introduced between vowel F0s (Assmann and Summerfield, 1989; Assmann and Summerfield, 1990; Assmann and Summerfield, 1994; Culling, 1990; McKeown, 1992; Scheffers, 1983; Zwicker, 1984). This improvement is referred to as the “F0-benefit” (Arehart et al, 1997; Bidelman and Yellamsetty, 2017; Chintanpalli et al, 2014; Chintanpalli and Heinz, 2013; Chintanpalli et al, 2016; Yellamsetty and Bidelman, 2018).…”

Modeling the level-dependent changes of concurrent vowel scores

“…The task of the listener is to identify both vowels, and performance is measured as a function of F0 difference between the two vowels. For YNH listeners, identification scores for both vowels improve as F0 difference increases between the two vowels, and then asymptotes usually at $3-Hz F0 difference or higher (Assmann and Summerfield, 1990;Summerfield and Assmann, 1991;Culling and Darwin, 1993;Arehart et al, 1997Arehart et al, , 2005Summers and Leek, 1998;Vongpaisal and Pichora-Fuller, 2007;Chintanpalli and Heinz, 2013;Chintanpalli et al, 2016). However, these studies have been typically conducted at a single vowel level.…”