scholarly journals Mutual information analysis of neural representations of speech in noise in the aging midbrain

2019 ◽  
Vol 122 (6) ◽  
pp. 2372-2387 ◽  
Author(s):  
Peng Zan ◽  
Alessandro Presacco ◽  
Samira Anderson ◽  
Jonathan Z. Simon
Keyword(s):  
Older Adults ◽  
Mutual Information ◽  
Normal Hearing ◽  
Information Analysis ◽  
Frequency Following Response ◽  
Speech In Noise ◽  
Clinically Normal ◽  
Age Related ◽  
Competing Speech ◽  
Mutual Information Analysis

Younger adults with normal hearing can typically understand speech in the presence of a competing speaker without much effort, but this ability to understand speech in challenging conditions deteriorates with age. Older adults, even with clinically normal hearing, often have problems understanding speech in noise. Earlier auditory studies using the frequency-following response (FFR), primarily believed to be generated by the midbrain, demonstrated age-related neural deficits when analyzed with traditional measures. Here we use a mutual information paradigm to analyze the FFR to speech (masked by a competing speech signal) by estimating the amount of stimulus information contained in the FFR. Our results show, first, a broadband informational loss associated with aging for both FFR amplitude and phase. Second, this age-related loss of information is more severe in higher-frequency FFR bands (several hundred hertz). Third, the mutual information between the FFR and the stimulus decreases as noise level increases for both age groups. Fourth, older adults benefit neurally, i.e., show a reduction in loss of information, when the speech masker is changed from meaningful (talker speaking a language that they can comprehend, such as English) to meaningless (talker speaking a language that they cannot comprehend, such as Dutch). This benefit is not seen in younger listeners, which suggests that age-related informational loss may be more severe when the speech masker is meaningful than when it is meaningless. In summary, as a method, mutual information analysis can unveil new results that traditional measures may not have enough statistical power to assess. NEW & NOTEWORTHY Older adults, even with clinically normal hearing, often have problems understanding speech in noise. Auditory studies using the frequency-following response (FFR) have demonstrated age-related neural deficits with traditional methods. Here we use a mutual information paradigm to analyze the FFR to speech masked by competing speech. Results confirm those from traditional analysis but additionally show that older adults benefit neurally when the masker changes from a language that they comprehend to a language they cannot.

scholarly journals Mutual Information Analysis of Neural Representations of Speech in Noise in the Aging Midbrain

2019 ◽  
Author(s):  
Peng Zan ◽  
Alessandro Presacco ◽  
Samira Anderson ◽  
Jonathan Z. Simon
Keyword(s):  
Older Adults ◽  
Mutual Information ◽  
Normal Hearing ◽  
Information Analysis ◽  
Frequency Following Response ◽  
Speech In Noise ◽  
Clinically Normal ◽  
Age Related ◽  
Competing Speech ◽  
Mutual Information Analysis

AbstractYounger adults with normal hearing can typically understand speech in the presence of a competing speaker without much effort, but this ability to understand speech in challenging conditions deteriorates with age. Older adults, even with clinically normal hearing, often have problems understanding speech in noise. Earlier auditory studies using the frequency-following response (FFR), primarily believed generated by the midbrain, have demonstrated age-related neural deficits when analyzed using traditional measures. Here we use a mutual information paradigm to analyze the FFR to speech (masked by a competing speech signal) by estimating the amount of stimulus information contained in the FFR. Our results show, first, a broad-band informational loss associated with aging for both FFR amplitude and phase. Second, this age-related loss of information is more severe in higher frequency FFR bands (several hundred Hz). Third, the mutual information between the FFR and the stimulus decreases as noise level increases for both age groups. Fourth, older adults benefit neurally, i.e., show a reduction in loss of information, when the speech masker is changed from meaningful (talker speaking a language that they can comprehend, such as English) to meaningless (talker speaking a language that they cannot comprehend, such as Dutch). This benefit is not seen in younger listeners, which suggests age-related informational loss may be more severe when the speech masker is meaningful than when it is meaningless. In summary, as a method, mutual information analysis can unveil new results that traditional measures may not have enough statistical power to assess.New & NoteworthyOlder adults, even with clinically normal hearing, often have problems understanding speech in noise. Auditory studies using the frequency-following response (FFR) have demonstrated age-related neural deficits using traditional methods. Here we use a mutual information paradigm to analyze the FFR to speech masked by competing speech. Results confirm those using traditional analysis, but additionally show that older adults benefit neurally when the masker changes from a language that they comprehend to a language they cannot.

scholarly journals Representation of speech in noise in the aging midbrain and cortex: aging may dominate over hearing-loss

2017 ◽  
Author(s):  
Alessandro Presacco ◽  
Jonathan Z. Simon ◽  
Samira Anderson
Keyword(s):  
Older Adults ◽  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Temporal Processing ◽  
Normal Hearing ◽  
Sensorineural Hearing ◽  
Speech In Noise ◽  
Age Related ◽  
Cortical Responses ◽  
Processing Deficits

ABSTRACTObjectiveTo understand the effect of peripheral hearing loss on the representation of speech in noise in the aging midbrain and cortex.MethodsSubjects comprised 17 normal-hearing younger adults, 15 normal-hearing older adults and 14 hearing-impaired older adults. The midbrain response, measured with Frequency-Following Responses (FFRs), and the cortical response, measured with magnetoencephalography (MEG) responses, were recorded from subjects listening to speech in quiet and noise at varying signal to noise ratios (SNRs).ResultsBoth groups of older listeners showed both weaker midbrain response amplitudes and overrepresentation of cortical responses compared to younger listeners. However, significant differences between the older groups were found in both midbrain-cortex relationships and in cortical processing durations, suggesting that hearing loss may alter reciprocal connections between lower and higher levels of the auditory pathway.ConclusionsThe paucity of differences in midbrain or cortical responses between the two older groups suggest that age-related temporal processing deficits may contribute to older adults’ communication difficulties beyond what might be predicted from peripheral hearing loss alone.SignificanceClinical devices, such as hearing aids, should not ignore age-related temporal processing deficits in the design of algorithms to maximize user benefit.HIGHLIGHTSMild sensorineural hearing loss does not appear to significantly exacerbate already appreciable age-related deficits in midbrain speech-in-noise encoding.Mild sensorineural hearing loss also does not appear to significantly exacerbate already appreciable age-related deficits in most measures of cortical speech-in-noise encoding.Central processing deficits caused by peripheral hearing loss in older adults are seen only in more subtle measures, including altered relationships between midbrain and cortex.

scholarly journals Age-related differences in binaural masking level differences: behavioral and electrophysiological evidence

2018 ◽  
Vol 120 (6) ◽  
pp. 2939-2952 ◽  
Author(s):  
Samira Anderson ◽  
Robert Ellis ◽  
Julie Mehta ◽  
Matthew J. Goupell
Keyword(s):  
Aging Effect ◽  
Normal Hearing ◽  
Behavioral Experiment ◽  
Spatial Cues ◽  
Sound Sources ◽  
Frequency Following Response ◽  
Binaural Processing ◽  
Threshold Difference ◽  
Age Related ◽  
Effects Of Aging

The effects of aging and stimulus configuration on binaural masking level differences (BMLDs) were measured behaviorally and electrophysiologically, using the frequency-following response (FFR) to target brainstem/midbrain encoding. The tests were performed in 15 younger normal-hearing (<30 yr) and 15 older normal-hearing (>60 yr) participants. The stimuli consisted of a 500-Hz target tone embedded in a narrowband (50-Hz bandwidth) or wideband (1,500-Hz bandwidth) noise masker. The interaural phase conditions included NoSo (tone and noise presented interaurally in-phase), NoSπ (noise presented interaurally in-phase and tone presented out-of-phase), and NπSo (noise presented interaurally out-of-phase and tone presented in-phase) configurations. In the behavioral experiment, aging reduced the magnitude of the BMLD. The magnitude of the BMLD was smaller for the NoSo–NπSo threshold difference compared with the NoSo–NoSπ threshold difference, and it was also smaller in narrowband compared with wideband conditions, consistent with previous measurements. In the electrophysiology experiment, older participants had reduced FFR magnitudes and smaller differences between configurations. There were significant changes in FFR magnitude between the NoSo to NoSπ configurations but not between the NoSo to NπSo configurations. The age-related reduction in FFR magnitudes suggests a temporal processing deficit, but no correlation was found between FFR magnitudes and behavioral BMLDs. Therefore, independent mechanisms may be contributing to the behavioral and neural deficits. Specifically, older participants had higher behavioral thresholds than younger participants for the NoSπ and NπSo configurations but had equivalent thresholds for the NoSo configuration. However, FFR magnitudes were reduced in older participants across all configurations. NEW & NOTEWORTHY Behavioral and electrophysiological testing reveal an aging effect for stimuli presented in wideband and narrowband noise conditions, such that behavioral binaural masking level differences and subcortical spectral magnitudes are reduced in older compared with younger participants. These deficits in binaural processing may limit the older participant's ability to use spatial cues to understand speech in environments containing competing sound sources.

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