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Medicine and Health Sciences

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University of Massachusetts Amherst

Karen S Helfer

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Aging And The Perception Of Temporally-Interleaved Words, Karen S. Helfer, Christine R. Mason, Christine Marino Mar 2013

Aging And The Perception Of Temporally-Interleaved Words, Karen S. Helfer, Christine R. Mason, Christine Marino

Karen S Helfer

No abstract provided.


Aging, Spacial Cues, And Single-Versus Dual-Task Performance In Competing Speech Perception, Karen S. Helfer, Jamie Chevalier, Richard L. Freyman Sep 2010

Aging, Spacial Cues, And Single-Versus Dual-Task Performance In Competing Speech Perception, Karen S. Helfer, Jamie Chevalier, Richard L. Freyman

Karen S Helfer

Older individuals often report difficulty coping in situations with multiple conversations in which they at times need to "tune out" the background speech and at other times seek to monitor competing messages. The present study was designed to simulate this type of interaction by examining the cost of requiring listeners to perform a secondary task in conjunction with understanding a target talker in the presence of competing speech. The ability of younger and older adults to understand a target utterance was measured with and without requiring the listener to also determine how many masking voices were presented time-reversed. Also of …


Lexical And Indexical Cues In Masking By Competing Speech, Karen S. Helfer, Richard L. Freyman Nov 2008

Lexical And Indexical Cues In Masking By Competing Speech, Karen S. Helfer, Richard L. Freyman

Karen S Helfer

Three experiments were conducted using the TVM sentences, a new set of stimuli for competing speech research. These open-set sentences incorporate a cue name that allows the experimenter to direct the listener's attention to a target sentence. The first experiment compared the relative efficacy of directing the listener's attention to the cue name versus instructing the subject to listen for a particular talker's voice. Results demonstrated that listeners could use either cue about equally well to find the target sentence. Experiment 2 was designed to determine whether differences in intelligibility among talkers' voices that were noted when three utterances were …


Aging And Speech-On-Speech Masking, Karen S. Helfer, Richard L. Freyman Jan 2008

Aging And Speech-On-Speech Masking, Karen S. Helfer, Richard L. Freyman

Karen S Helfer

Objectives A common complaint of many older adults is difficulty communicating in situations where they must focus on one talker in the presence of other people speaking. In listening environments containing multiple talkers, age-related changes may be caused by increased sensitivity to energetic masking, increased susceptibility to informational masking (e.g., confusion between the target voice and masking voices), and/or cognitive deficits. The purpose of the present study was to tease out these contributions to the difficulties that older adults experience in speech-on-speech masking situations. Design Groups of younger, normal-hearing individuals and older adults with varying degrees of hearing sensitivity (n …


Spatial Release From Masking With Noise-Vocoded Speech, Richard L. Freyman, Uma Balakrishnan, Karen S. Helfer Jan 2008

Spatial Release From Masking With Noise-Vocoded Speech, Richard L. Freyman, Uma Balakrishnan, Karen S. Helfer

Karen S Helfer

This study investigated how confusability between target and masking utterances affects the masking release achieved through spatial separation. Important distinguishing characteristics between competing voices were removed by processing speech with six-channel envelope vocoding, which simulates some aspects of listening with a cochlear implant. In the first experiment, vocoded target nonsense sentences were presented against two-talker vocoded maskers in conditions that provide different spatial impressions but not reliable cues that lead to traditional release from masking. Surprisingly, no benefit of spatial separation was found. The absence of spatial release was hypothesized to be the result of the highly positive target-to-masker ratios …


Speech Intelligibility In Cochlear Implant Simulations: Effects Of Carrier Type, Interfering Noise, And Subject Experience, Nathaniel A. Whitmal Iii, Sarah F. Poissant, Richard L. Freyman, Karen S. Helfer Jan 2007

Speech Intelligibility In Cochlear Implant Simulations: Effects Of Carrier Type, Interfering Noise, And Subject Experience, Nathaniel A. Whitmal Iii, Sarah F. Poissant, Richard L. Freyman, Karen S. Helfer

Karen S Helfer

Channel vocoders using either tone or band-limited noise carriers have been used in experiments to simulate cochlear implant processing in normal-hearing listeners. Previous results from these experiments have suggested that the two vocoder types produce speech of nearly equal intelligibility in quiet conditions. The purpose of this study was to further compare the performance of tone and noise-band vocoders in both quiet and noisy listening conditions. In each of four experiments, normal-hearing subjects were better able to identify tone-vocoded sentences and vowel-consonant-vowel syllables than noise-vocoded sentences and syllables, both in quiet and in the presence of either speech-spectrum noise or …


Effect Of Number Of Masking Talkers And Auditory Priming On Informational Masking In Speech Recognition, Richard L. Freyman, Uma Balakrishnan, Karen S. Helfer Jan 2005

Effect Of Number Of Masking Talkers And Auditory Priming On Informational Masking In Speech Recognition, Richard L. Freyman, Uma Balakrishnan, Karen S. Helfer

Karen S Helfer

Three experiments investigated factors that influence the creation of and release from informational masking in speech recognition. The target stimuli were nonsense sentences spoken by a female talker. In experiment 1 the masker was a mixture of three, four, six, or ten female talkers, all reciting similar nonsense sentences. Listeners’ recognition performance was measured with both target and masker presented from a front loudspeaker ~F–F! or with a masker presented from two loudspeakers, with the right leading the front by 4 ms ~F–RF!. In the latter condition the target and masker appear to be from different locations. This aids recognition …