RESUMEN
Listeners weight acoustic cues in speech according to their reliability, but few studies have examined how cue weights change across the lifespan. Previous work has suggested that older adults have deficits in auditory temporal discrimination, which could affect the reliability of temporal phonetic cues, such as voice onset time (VOT), and in turn, impact speech perception in real-world listening environments. We addressed this by examining younger and older adults' use of VOT and onset F0 (a secondary phonetic cue) for voicing judgments (e.g., /b/ vs. /p/), using both synthetic and naturally produced speech. We found age-related differences in listeners' use of the two voicing cues, such that older adults relied more heavily on onset F0 than younger adults, even though this cue is less reliable in American English. These results suggest that phonetic cue weights continue to change across the lifespan.
Asunto(s)
Envejecimiento/psicología , Señales (Psicología) , Periodicidad , Acústica del Lenguaje , Percepción del Habla , Calidad de la Voz , Adolescente , Adulto , Factores de Edad , Humanos , Juicio , Persona de Mediana Edad , Factores de Tiempo , Adulto JovenRESUMEN
Speech perception, especially in noise, may be maximized if the perceiver observes the naturally occurring visual-plus-auditory cues inherent in the production of spoken language. Evidence is conflicting, however, about which aspects of visual information mediate enhanced speech perception in noise. For this reason, we investigated the relative contributions of audibility and the type of visual cue in three experiments in young adults with normal hearing and vision. Relative to static visual cues, access to the talker's phonetic gestures in speech production, especially in noise, was associated with (a) faster response times and sensitivity for speech understanding in noise, and (b) shorter latencies and reduced amplitudes of auditory N1 event-related potentials. Dynamic chewing facial motion also decreased the N1 latency, but only meaningful linguistic motions reduced the N1 amplitude. The hypothesis that auditory-visual facilitation is distinct to properties of natural, dynamic speech gestures was partially supported.
Asunto(s)
Señales (Psicología) , Potenciales Evocados Auditivos , Cara , Movimiento , Ruido , Fonética , Percepción del Habla , Estimulación Acústica , Acústica , Adulto , Femenino , Humanos , Masculino , Estimulación Luminosa , Tiempo de Reacción , Habla , Factores de TiempoRESUMEN
OBJECTIVE: A pair of experiments investigated the hypothesis that bimodal (auditory-visual) speech presentation and expanded auditory bandwidth would improve speech intelligibility and increase working memory performance for older adults by reducing the cognitive effort needed for speech perception. BACKGROUND: Although telephone communication is important for helping older adults maintain social engagement, age-related sensory and working memory limits may make telephone conversations difficult. METHOD: Older adults with either age-normal hearing or mild-to-moderate sensorineural hearing loss performed a running memory task. Participants heard word strings of unpredictable length and at the end of each string were required to repeat back the final three words.Words were presented monaurally in telephone bandwidth (300 Hz to 3300 Hz) or expanded bandwidth (50 Hz to 7500 Hz), in quiet (65 dBZ SPL), or in white noise (65 dBZ SPL with noise at 60 dBZ SPL), with or without a visual display of the talker. RESULTS: In quiet listening conditions, bimodal presentation increased the number of words correctly reported per trial but only for listeners with hearing loss and with high lipreading proficiency. Stimulus bandwidth did not affect performance. In noise, bimodal presentation and expanded bandwidth improved performance for all participant groups but did so by improving speech intelligibility, not by improving working memory. CONCLUSION: Expanded bandwidth and bimodal presentation can improve speech perceptibility in difficult listening conditions but may not always improve working memory performance. APPLICATION: Results can inform the design of telephone features to improve ease of communication for older adults.
Asunto(s)
Envejecimiento , Comunicación , Pérdida Auditiva , Trastornos de la Memoria , Percepción del Habla , Adulto , Audiometría , Femenino , Pérdida Auditiva/diagnóstico , Pérdida Auditiva Sensorineural/diagnóstico , Humanos , Masculino , Trastornos de la Memoria/diagnóstico , Persona de Mediana EdadRESUMEN
The goals of this study were to measure sensitivity to the direct-to-reverberant energy ratio (D/R) across a wide range of D/R values and to gain insight into which cues are used in the discrimination process. The main finding is that changes in D/R are discriminated primarily based on spectral cues. Temporal cues may be used but only when spectral cues are diminished or not available, while sensitivity to interaural cross-correlation is too low to be useful in any of the conditions tested. These findings are based on an acoustic analysis of these variables and the results of two psychophysical experiments. The first experiment employs wideband noise with two values for onset and offset times to determine the D/R just-noticeable difference at -10, 0, 10, and 20 dB D/R. This yielded substantially higher sensitivity to D/R at 0 and 10 dB D/R (2-3 dB) than has been reported previously, while sensitivity is much lower at -10 and 20 dB D/R. The second experiment consists of three parts where specific cues to D/R are reduced or removed, which enabled the specified rank ordering of the cues. The acoustic analysis and psychophysical experiments also provide an explanation for the "auditory horizon effect."
Asunto(s)
Percepción Auditiva , Acústica , Adulto , Señales (Psicología) , Femenino , Humanos , Masculino , Modelos Biológicos , Ruido , PsicofísicaRESUMEN
OBJECTIVES: The purpose of this study was to examine characteristics of eye gaze behavior, specifically eye fixations, during reception of simultaneous communication (SC). SC was defined as conceptually accurate and semantically based signs and fingerspelling used in conjunction with speech. Specific areas of focus were (1) the pattern of frequency, duration, and location of observers' eye fixations in relation to the critical source of disambiguating information (signs or speech) in SC, and (2) how the pattern of an observer's eye fixations was related to the source of critical information (sign or speech), expectations regarding the location of the critical information after exposure to the stimulus set, observer characteristics, and sender. DESIGN: The investigation used eye tracking technology to monitor eye fixations of observers who watched silent video clips of sentences rendered in SC by three senders. Each sentence contained one of a pair of sign-critical (e.g., "sleeves"/"leaves") or speech-critical (e.g., "invited"/"hired") contrast items designed to depend on information at the hands or mouth, respectively, to resolve its ambiguity. Observers were 20 adults: five faculty/staff with early onset deafness, five faculty/staff with normal hearing, and ten college students with early onset deafness. Faculty and staff were identified by a sign language assessment specialist to be experienced and skillful users of SC. Students, exposed to SC in classroom instruction, were recruited through paper and electronic ads. RESULTS: Generally, observers looked toward the face, regardless of whether signs or speech disambiguated the message, suggesting that eye fixations toward the hands of the sender are not necessary to apprehend essential information to accurately identify an ambiguous part of the message during SC. However, other aspects of eye behavior indicated sensitivity to type of critical contrast. In particular, fixations were shorter during sign-critical items compared to speech-critical items, even after adjusting for stimulus length. In addition, experienced, adult deaf users of SC made more, brief eye fixations than observers who had normal hearing. Finally, differences in eye fixation patterns toward different senders indicates that sender characteristics affect visual processes in SC perception. CONCLUSIONS: This study provides supportive evidence of brief, frequent eye movements by deaf perceivers over small areas of a video display during reception of visuospatial linguistic information. These movements could be used to enhance activation of brain centers responsible for processing motion, consistent with neurophysiological evidence of attentional mechanisms or visual processes unique to perception of a visual language.
Asunto(s)
Sordera/fisiopatología , Fijación Ocular/fisiología , Lengua de Signos , Adulto , Atención , Estudios de Casos y Controles , Movimientos Oculares/fisiología , Femenino , Humanos , Lectura de los Labios , Masculino , Análisis Multivariante , Encuestas y Cuestionarios , Factores de Tiempo , Grabación de Cinta de VideoRESUMEN
Extraction of a target sound source amidst multiple interfering sound sources is difficult when there are fewer sensors than sources, as is the case for human listeners in the classic cocktail-party situation. This study compares the signal extraction performance of five algorithms using recordings of speech sources made with three different two-microphone arrays in three rooms of varying reverberation time. Test signals, consisting of two to five speech sources, were constructed for each room and array. The signals were processed with each algorithm, and the signal extraction performance was quantified by calculating the signal-to-noise ratio of the output. A frequency-domain minimum-variance distortionless-response beamformer outperformed the time-domain based Frost beamformer and generalized sidelobe canceler for all tests with two or more interfering sound sources, and performed comparably or better than the time-domain algorithms for tests with one interfering sound source. The frequency-domain minimum-variance algorithm offered performance comparable to that of the Peissig-Kollmeier binaural frequency-domain algorithm, but with much less distortion of the target signal. Comparisons were also made to a simple beamformer. In addition, computer simulations illustrate that, when processing speech signals, the chosen implementation of the frequency-domain minimum-variance technique adapts more quickly and accurately than time-domain techniques.
Asunto(s)
Atención , Pruebas de Audición Dicótica , Audífonos , Enmascaramiento Perceptual , Medio Social , Acústica del Lenguaje , Percepción del Habla , Algoritmos , Análisis de Fourier , Audífonos/estadística & datos numéricos , Humanos , Percepción Sonora , Cómputos Matemáticos , Discriminación de la Altura Tonal , Diseño de Prótesis , Espectrografía del Sonido , Pruebas de Discriminación del HablaRESUMEN
The reverberation time (RT) is an important parameter for characterizing the quality of an auditory space. Sounds in reverberant environments are subject to coloration. This affects speech intelligibility and sound localization. Many state-of-the-art audio signal processing algorithms, for example in hearing-aids and telephony, are expected to have the ability to characterize the listening environment, and turn on an appropriate processing strategy accordingly. Thus, a method for characterization of room RT based on passively received microphone signals represents an important enabling technology. Current RT estimators, such as Schroeder's method, depend on a controlled sound source, and thus cannot produce an online, blind RT estimate. Here, a method for estimating RT without prior knowledge of sound sources or room geometry is presented. The diffusive tail of reverberation was modeled as an exponentially damped Gaussian white noise process. The time-constant of the decay, which provided a measure of the RT, was estimated using a maximum-likelihood procedure. The estimates were obtained continuously, and an order-statistics filter was used to extract the most likely RT from the accumulated estimates. The procedure was illustrated for connected speech. Results obtained for simulated and real room data are in good agreement with the real RT values.
Asunto(s)
Percepción Auditiva , Modelos Teóricos , Percepción del Tiempo , Acústica , Ambiente , HumanosRESUMEN
In this study, we investigated where people look on talkers' faces as they try to understand what is being said. Sixteen young adults with normal hearing and demonstrated average speechreading proficiency were evaluated under two modality presentation conditions: vision only versus vision plus low-intensity sound. They were scored for the number of words correctly identified from 80 unconnected sentences spoken by two talkers. The results showed two competing tendencies: an eye primacy effect that draws the gaze to the talkers eyes during silence and an information source attraction effect that draws the gaze to the talker's mouth during speech periods. Dynamic shifts occur between eyes and mouth prior to speech onset and following the offset of speech, and saccades tend to be suppressed during speech periods. The degree to which the gaze is drawn to the mouth during speech and the degree to which saccadic activity is suppressed depend on the difficulty of the speech identification task. Under the most difficult modality presentation condition, vison only, accuracy was related to average sentence difficulty and individual proficiency in visual speech perception, but not to the proportion of gaze time directed toward the talkers mouth or toward other parts of the talker's face.
Asunto(s)
Percepción Auditiva , Fijación Ocular , Percepción Espacial , Percepción del Habla , Percepción Visual , Vocabulario , Adolescente , Adulto , HumanosRESUMEN
Although Central Institute for the Deaf (CID) W-1 stimuli are routinely used for speech recognition threshold (SRT) testing, they are not always familiar to new learners of English and often lead to erroneous assessments. To improve test accuracy, alternative stimuli were constructed by pairing familiar English digits. These digit pairs were used to measure SRT for 12 non-native speakers of English and 12 native speakers of English. Results indicate that digit pairs effectively measure SRT for both participant groups; and more importantly, for non-native speakers of English, digit pairs are more accurate than CID W-1 words in measuring the hearing threshold for speech. Digit-pairs have cross-linguistic appeal and should greatly facilitate accurate SRT testing for listeners with minimal exposure to English.