Biomedical subjects

K S Helfer

Publications and source records attributed to K S Helfer.

9 recordsLinked to original sources

PubMed2001

Spatial release from informational masking in speech recognition.

Three experiments were conducted to determine the extent to which perceived separation of speech and interference improves speech recognition in the free field. Target speech stimuli were 320 grammatically correct but nonmeaningful sentences spoken by a female talker. In the first experiment the interference was a recording of either one or two female talkers reciting a continuous stream of similar nonmeaningful sentences. The target talker was always presented from a loudspeaker directly in front (0 degrees). The interference was either presented from the front loudspeaker (the F-F condition) or from both a right loudspeaker (60 degrees) and the front loudspeaker, with the right leading the front by 4 ms (the F-RF condition). Due to the precedence effect, the interference in the F-RF condition was perceived to be well to the right, while the target talker was heard from the front. For both the single-talker and two-talker interference, there was a sizable improvement in speech recognition in the F-RF condition compared with the F-F condition. However, a second experiment showed that there was no F-RF advantage when the interference was noise modulated by the single- or multi-channel envelope of the two-talker masker. Results of the third experiment indicated that the advantage of perceived separation is not limited to conditions where the interfering speech is understandable.

Adult↗

PubMed1999

Continuing education in audiology: what do we want?

A sample of audiologists practicing in the New England states was surveyed about topics of interest for continuing education, desire to obtain a professional doctoral degree, and preferred learning modes for completing continuing education activities and doctoral education. Two hundred sixty-eight completed surveys were returned. Respondents indicated interest in a wide range of continuing education topics, with the greatest amount of interest in areas related to technology. The majority of respondents preferred to complete continuing education activities via traditional, face-to-face programming, whereas most respondents indicated interest in using both traditional and distance-learning methods to upgrade to a professional doctoral degree. Results of the survey also showed that a large proportion of audiologists are undecided about their desire to obtain a professional doctoral degree.

Audiology↗

PubMed1999

The role of perceived spatial separation in the unmasking of speech.

Spatial separation of speech and noise in an anechoic space creates a release from masking that often improves speech intelligibility. However, the masking release is severely reduced in reverberant spaces. This study investigated whether the distinct and separate localization of speech and interference provides any perceptual advantage that, due to the precedence effect, is not degraded by reflections. Listeners' identification of nonsense sentences spoken by a female talker was measured in the presence of either speech-spectrum noise or other sentences spoken by a second female talker. Target and interference stimuli were presented in an anechoic chamber from loudspeakers directly in front and 60 degrees to the right in single-source and precedence-effect (lead-lag) conditions. For speech-spectrum noise, the spatial separation advantage for speech recognition (8 dB) was predictable from articulation index computations based on measured release from masking for narrow-band stimuli. The spatial separation advantage was only 1 dB in the lead-lag condition, despite the fact that a large perceptual separation was produced by the precedence effect. For the female talker interference, a much larger advantage occurred, apparently because informational masking was reduced by differences in perceived locations of target and interference.

Female↗

PubMed1998

Auditory and auditory-visual recognition of clear and conversational speech by older adults.

Research has shown that speech articulated in a clear manner is easier to understand than conversationally spoken speech in both the auditory-only (A-only) and auditory-visual (AV) domains. Because this research has been conducted using younger adults, it is unknown whether age-related changes in auditory and/or visual processing affect older adults' ability to benefit when a talker speaks clearly. The present study examined how speaking mode (clear vs conversational) and presentation mode (A-only vs AV) influenced nonsense sentence recognition by older listeners. Results showed that neither age nor hearing loss limited the amount of benefit that older adults obtained from a talker speaking clearly. However, age was inversely correlated with identification of AV (but not A-only) conversational speech, even when pure-tone thresholds were controlled statistically.

Aged↗

PubMed1997

Auditory and auditory-visual perception of clear and conversational speech.

Research has shown that speaking in a deliberately clear manner can improve the accuracy of auditory speech recognition. Allowing listeners access to visual speech cues also enhances speech understanding. Whether the nature of information provided by speaking clearly and by using visual speech cues is redundant has not been determined. This study examined how speaking mode (clear vs. conversational) and presentation mode (auditory vs. auditory-visual) influenced the perception of words within nonsense sentences. In Experiment 1, 30 young listeners with normal hearing responded to videotaped stimuli presented audiovisually in the presence of background noise at one of three signal-to-noise ratios. In Experiment 2, 9 participants returned for an additional assessment using auditory-only presentation. Results of these experiments showed significant effects of speaking mode (clear speech was easier to understand than was conversational speech) and presentation mode (auditory-visual presentation led to better performance than did auditory-only presentation). The benefit of clear speech was greater for words occurring in the middle of sentences than for words at either the beginning or end of sentences for both auditory-only and auditory-visual presentation, whereas the greatest benefit from supplying visual cues was for words at the end of sentences spoken both clearly and conversationally. The total benefit from speaking clearly and supplying visual cues was equal to the sum of each of these effects. Overall, the results suggest that speaking clearly and providing visual speech information provide complementary (rather than redundant) information.

Adult↗

PubMed1994

Binaural cues and consonant perception in reverberation and noise.

Although a binaural advantage for understanding speech in adverse listening conditions has long been recognized, little is known about how binaural hearing influences consonant error patterns. The goal of the present study was to examine differences in consonant perception when stimuli distorted by noise and/or reverberation were presented using monaural, binaural, and diotic presentation modes. Results showed significant differences in error patterns among the three listening conditions (noise, reverberation, and reverberation + noise). Differences among the three presentation modes (monaural, binaural, and diotic) were subtle, as were interactions among presentation modes and listening conditions.

Acoustic Stimulation↗

PubMed1992

Aging and the binaural advantage in reverberation and noise.

The consonant identification ability of younger normal-hearing adults and older adults with little or no peripheral hearing loss was assessed using monaural and binaural presentation in four listening conditions: quiet, noise, reverberation, and reverberation + noise. Performance was examined in terms of identification accuracy and amount of binaural advantage. Results suggest that the small amount of hearing loss in the older subjects limited their perception of distorted consonants. Neither age nor peripheral hearing loss was related strongly to the amount of benefit obtained from binaural presentation.

Acoustic Stimulation↗

PubMed1991

Aging and consonant errors in reverberation and noise.

Identification accuracy and error patterns on the City University of New York (CUNY) Nonsense Syllable Test were examined for three groups of subjects (young normal-hearing, older hearing-impaired, and older with minimal hearing loss) listening binaurally in four conditions (quiet, noise, reverberation, and reverberation plus noise). Percent-correct performance was analyzed for stimuli aggregated by place and manner categories, and error patterns were examined via analysis of variance and correlational procedures. Results suggested that some of the difficulty experienced by the older subjects was related to amount of hearing loss, but a portion of the data could not be explained by elevated auditory thresholds. Confusion patterns also varied across listening conditions, especially for the nasal and semivowel stimuli.

Adult↗

PubMed1990

Hearing loss, aging, and speech perception in reverberation and noise.

The present investigation examined the effect of reverberation and noise on the perception of nonsense syllables by four groups of subjects: younger (less than or equal to 35 years of age) and older (greater than 60 years of age) listeners with mild-to-moderate sensorineural hearing loss; younger, normal-hearing individuals; and older adults with minimal peripheral hearing loss. Copies of the Nonsense Syllable Test (Resnick, Dubno, Huffnung, & Levitt, 1975) were re-recorded under four levels of reverberation (0.0, 0.6, 0.9, 1.3 s) in quiet and in cafeteria noise at +10 dB S:N. Results suggest that both age and amount of pure-tone hearing loss contribute to senescent changes in the ability to understand noisy, reverberant speech: pure-tone threshold and age were correlated negatively with performance in reverberation plus noise, although age and pure-tone hearing loss were not correlated with each other. Further, many older adults with minimal amounts of peripheral hearing loss demonstrated difficulty understanding distorted consonants.

Adult↗