Noise and pitch interact during the cortical segregation of concurrent speech

Publication date: Available online 25 May 2017
Source:Hearing Research
Author(s): Gavin M. Bidelman, Anusha Yellamsetty
Behavioral studies reveal listeners exploit intrinsic differences in voice fundamental frequency (F0) to segregate concurrent speech sounds—the so-called “F0-benefit.” More favorable signal-to-noise ratio (SNR) in the environment, an extrinsic acoustic factor, similarly benefits the parsing of simultaneous speech. Here, we examined the neurobiological substrates of these two cues in the perceptual segregation of concurrent speech mixtures. We recorded event-related brain potentials (ERPs) while listeners performed a speeded double-vowel identification task. Listeners heard two concurrent vowels whose F0 differed by zero or four semitones presented in either clean (no noise) or noise-degraded (+5 dB SNR) conditions. Behaviorally, listeners were more accurate in correctly identifying both vowels for larger F0 separations but F0-benefit was more pronounced at more favorable SNRs (i.e., pitch × SNR interaction). Analysis of the ERPs revealed that only the P2 wave (∼200 ms) showed a similar F0 x SNR interaction as behavior and was correlated with listeners' perceptual F0-benefit. Neural classifiers applied to the ERPs further suggested that speech sounds are segregated neurally within 200 ms based on SNR whereas segregation based on pitch occurs later in time (400–700 ms). The earlier timing of extrinsic SNR compared to intrinsic F0-based segregation implies that the cortical extraction of speech from noise is more efficient than differentiating speech based on pitch cues alone, which may recruit additional cortical processes. Findings indicate that noise and pitch differences interact relatively early in cerebral cortex and that the brain arrives at the identities of concurrent speech mixtures as early as ∼200 ms.



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Brain activity underlying the recovery of meaning from degraded speech: A functional near-infrared spectroscopy (fNIRS) study

Publication date: Available online 25 May 2017
Source:Hearing Research
Author(s): Pramudi Wijayasiri, Douglas E.H. Hartley, Ian M. Wiggins
The purpose of this study was to establish whether functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique based on optical principles, is suitable for studying the brain activity that underlies effortful listening. In an event-related fNIRS experiment, normally-hearing adults listened to sentences that were either clear or degraded (noise vocoded). These sentences were presented simultaneously with a non-speech distractor, and on each trial participants were instructed to attend either to the speech or to the distractor. The primary region of interest for the fNIRS measurements was the left inferior frontal gyrus (LIFG), a cortical region involved in higher-order language processing. The fNIRS results confirmed findings previously reported in the functional magnetic resonance imaging (fMRI) literature. Firstly, the LIFG exhibited an elevated response to degraded versus clear speech, but only when attention was directed towards the speech. This attention-dependent increase in frontal brain activation may be a neural marker for effortful listening. Secondly, during attentive listening to degraded speech, the haemodynamic response peaked significantly later in the LIFG than in superior temporal cortex, possibly reflecting the engagement of working memory to help reconstruct the meaning of degraded sentences. The homologous region in the right hemisphere may play an equivalent role to the LIFG in some left-handed individuals. In conclusion, fNIRS holds promise as a flexible tool to examine the neural signature of effortful listening.



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Noise and pitch interact during the cortical segregation of concurrent speech

Publication date: Available online 25 May 2017
Source:Hearing Research
Author(s): Gavin M. Bidelman, Anusha Yellamsetty
Behavioral studies reveal listeners exploit intrinsic differences in voice fundamental frequency (F0) to segregate concurrent speech sounds—the so-called “F0-benefit.” More favorable signal-to-noise ratio (SNR) in the environment, an extrinsic acoustic factor, similarly benefits the parsing of simultaneous speech. Here, we examined the neurobiological substrates of these two cues in the perceptual segregation of concurrent speech mixtures. We recorded event-related brain potentials (ERPs) while listeners performed a speeded double-vowel identification task. Listeners heard two concurrent vowels whose F0 differed by zero or four semitones presented in either clean (no noise) or noise-degraded (+5 dB SNR) conditions. Behaviorally, listeners were more accurate in correctly identifying both vowels for larger F0 separations but F0-benefit was more pronounced at more favorable SNRs (i.e., pitch × SNR interaction). Analysis of the ERPs revealed that only the P2 wave (∼200 ms) showed a similar F0 x SNR interaction as behavior and was correlated with listeners' perceptual F0-benefit. Neural classifiers applied to the ERPs further suggested that speech sounds are segregated neurally within 200 ms based on SNR whereas segregation based on pitch occurs later in time (400–700 ms). The earlier timing of extrinsic SNR compared to intrinsic F0-based segregation implies that the cortical extraction of speech from noise is more efficient than differentiating speech based on pitch cues alone, which may recruit additional cortical processes. Findings indicate that noise and pitch differences interact relatively early in cerebral cortex and that the brain arrives at the identities of concurrent speech mixtures as early as ∼200 ms.



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Brain activity underlying the recovery of meaning from degraded speech: A functional near-infrared spectroscopy (fNIRS) study

Publication date: Available online 25 May 2017
Source:Hearing Research
Author(s): Pramudi Wijayasiri, Douglas E.H. Hartley, Ian M. Wiggins
The purpose of this study was to establish whether functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique based on optical principles, is suitable for studying the brain activity that underlies effortful listening. In an event-related fNIRS experiment, normally-hearing adults listened to sentences that were either clear or degraded (noise vocoded). These sentences were presented simultaneously with a non-speech distractor, and on each trial participants were instructed to attend either to the speech or to the distractor. The primary region of interest for the fNIRS measurements was the left inferior frontal gyrus (LIFG), a cortical region involved in higher-order language processing. The fNIRS results confirmed findings previously reported in the functional magnetic resonance imaging (fMRI) literature. Firstly, the LIFG exhibited an elevated response to degraded versus clear speech, but only when attention was directed towards the speech. This attention-dependent increase in frontal brain activation may be a neural marker for effortful listening. Secondly, during attentive listening to degraded speech, the haemodynamic response peaked significantly later in the LIFG than in superior temporal cortex, possibly reflecting the engagement of working memory to help reconstruct the meaning of degraded sentences. The homologous region in the right hemisphere may play an equivalent role to the LIFG in some left-handed individuals. In conclusion, fNIRS holds promise as a flexible tool to examine the neural signature of effortful listening.



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Noise and pitch interact during the cortical segregation of concurrent speech

Publication date: Available online 25 May 2017
Source:Hearing Research
Author(s): Gavin M. Bidelman, Anusha Yellamsetty
Behavioral studies reveal listeners exploit intrinsic differences in voice fundamental frequency (F0) to segregate concurrent speech sounds—the so-called “F0-benefit.” More favorable signal-to-noise ratio (SNR) in the environment, an extrinsic acoustic factor, similarly benefits the parsing of simultaneous speech. Here, we examined the neurobiological substrates of these two cues in the perceptual segregation of concurrent speech mixtures. We recorded event-related brain potentials (ERPs) while listeners performed a speeded double-vowel identification task. Listeners heard two concurrent vowels whose F0 differed by zero or four semitones presented in either clean (no noise) or noise-degraded (+5 dB SNR) conditions. Behaviorally, listeners were more accurate in correctly identifying both vowels for larger F0 separations but F0-benefit was more pronounced at more favorable SNRs (i.e., pitch × SNR interaction). Analysis of the ERPs revealed that only the P2 wave (∼200 ms) showed a similar F0 x SNR interaction as behavior and was correlated with listeners' perceptual F0-benefit. Neural classifiers applied to the ERPs further suggested that speech sounds are segregated neurally within 200 ms based on SNR whereas segregation based on pitch occurs later in time (400–700 ms). The earlier timing of extrinsic SNR compared to intrinsic F0-based segregation implies that the cortical extraction of speech from noise is more efficient than differentiating speech based on pitch cues alone, which may recruit additional cortical processes. Findings indicate that noise and pitch differences interact relatively early in cerebral cortex and that the brain arrives at the identities of concurrent speech mixtures as early as ∼200 ms.



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Brain activity underlying the recovery of meaning from degraded speech: A functional near-infrared spectroscopy (fNIRS) study

Publication date: Available online 25 May 2017
Source:Hearing Research
Author(s): Pramudi Wijayasiri, Douglas E.H. Hartley, Ian M. Wiggins
The purpose of this study was to establish whether functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique based on optical principles, is suitable for studying the brain activity that underlies effortful listening. In an event-related fNIRS experiment, normally-hearing adults listened to sentences that were either clear or degraded (noise vocoded). These sentences were presented simultaneously with a non-speech distractor, and on each trial participants were instructed to attend either to the speech or to the distractor. The primary region of interest for the fNIRS measurements was the left inferior frontal gyrus (LIFG), a cortical region involved in higher-order language processing. The fNIRS results confirmed findings previously reported in the functional magnetic resonance imaging (fMRI) literature. Firstly, the LIFG exhibited an elevated response to degraded versus clear speech, but only when attention was directed towards the speech. This attention-dependent increase in frontal brain activation may be a neural marker for effortful listening. Secondly, during attentive listening to degraded speech, the haemodynamic response peaked significantly later in the LIFG than in superior temporal cortex, possibly reflecting the engagement of working memory to help reconstruct the meaning of degraded sentences. The homologous region in the right hemisphere may play an equivalent role to the LIFG in some left-handed individuals. In conclusion, fNIRS holds promise as a flexible tool to examine the neural signature of effortful listening.



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PROPIONIBACTERIUM ACNES AND CHRONIC DISEASES : P. acnes is an opportunistic pathogen, causing a range of postoperative and device-related infections e.g., surgery,post-neurosurgical infection,joint prostheses, shunts and prosthetic heart valves. P. acnes may play a role in other conditions, including inflammation of the prostate leading to cancer,SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis) syndrome, sarcoidosis and sciatica.

http://otorhinolaryngology-crete.blogspot.com/2017/05/propionibacterium-acnes-and-chronic.html

P. acnes bacteria live deep within follicles and pores, away from the surface of the skin. In these follicles, P. acnes bacteria use sebum, cellular debris and metabolic byproducts from the surrounding skin tissue as their primary sources of energy and nutrients. Elevated production of sebum by hyperactive sebaceous glands (sebaceous hyperplasia) or blockage of the follicle can cause P. acnes bacteria to grow and multiply.[6]

P. acnes bacteria secrete many proteins, including several digestive enzymes.[7] These enzymes are involved in the digestion of sebum and the acquisition of other nutrients. They can also destabilize the layers of cells that form the walls of the follicle. The cellular damage, metabolic byproducts and bacterial debris produced by the rapid growth of P. acnes in follicles can trigger inflammation.[8] This inflammation can lead to the symptoms associated with some common skin disorders, such as folliculitis and acne vulgaris.[9][10][11]

The damage caused by P. acnes and the associated inflammation make the affected tissue more susceptible to colonization by opportunistic bacteria, such as Staphylococcus aureus. Preliminary research shows healthy pores are only colonized by P. acnes, while unhealthy ones universally include the nonpore-resident Staphylococcus epidermidis, amongst other bacterial contaminants. Whether this is a root causality, just opportunistic and a side effect, or a more complex pathological duality between P. acnes and this particular Staphylococcus species is not known.[12]

P. acnes has also been found in corneal ulcers, and is a common cause of chronic endophthalmitis following cataract surgery. Rarely, it infects heart valves leading to endocarditis, and infections of joints (septic arthritis) have been reported.[5] Furthermore, Propionibacterium species have been found in ventriculostomy insertion sites, and areas subcutaneous to suture sites in patients who have undergone craniotomy. It is a common contaminant in blood and cerebrospinal fluid cultures.

P. acnes has been found in herniated discs.[13] The propionic acid which it secretes creates micro-fractures of the surrounding bone. These micro-fractures are sensitive and it has been found that antibiotics have been helpful in resolving this type of low back pain.[14]

P. acnes can be found in bronchoalveolar lavage of approximately 70% of patients with sarcoidosis and is associated with disease activity, but it can be also found in 23% of controls.[15][16] The subspecies of P. acnes that cause these infections of otherwise sterile tissues (prior to medical procedures), however, are the same subspecies found on the skin of individuals who do not have acne-prone skin, so are likely local contaminants. Moderate to severe acne vulgaris appears to be more often associated with virulent strains.[17]

P. acnes is an opportunistic pathogen, causing a range of postoperative and device-related infections e.g., surgery,[18] post-neurosurgical infection,[19] joint prostheses, shunts and prosthetic heart valves. P. acnes may play a role in other conditions, including inflammation of the prostate leading to cancer,[20] SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis) syndrome, sarcoidosis and sciatica.[21]

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com