The effects of articulation on the acoustical structure of feline vocalizations.

Feline isolation calls were analyzed, and a model was developed to relate the acoustical features of these calls to the physical processes used in their production. Fifty isolation calls were recorded from each of five cats for a total sample of 250 vocalizations. By combinations of Fourier transform, autocorrelation, and linear prediction methods, the fundamental frequency (glottal-pulse period) F0, the energy of F0, the frequency having maximum energy Fmax (not always F0), and the energy at this frequency were computed. Mean F0 ranged from 400-600 Hz for individual cats. For some cats F0 was consistent within calls, but for other cats sudden shifts in F0 occurred within calls. Here, Fmax was almost a harmonic of F0 and generally ranged from 1-2 kHz. For individual cats, the energy ratio E = (energy of Fmax/energy of F0) varied from 1 to 60 and the grand average E over the time course of the call varied from about 12 to 38. The mean rms call intensity was an inverted-U function of time. Measured jaw opening was strongly correlated with acoustical features of call. A Bessel-horn model with time-varying flare gave a good account of acoustical parameters such as Fmax. The presence of formantlike resonances in cat vocalizations and the important role of jaw movements (vocal gestures) in the production of these calls suggest that cats may provide a useful model for some aspects of human vocal behavior.

Interactive factors in consonant confusion patterns.

Confusion patterns among English consonants were examined using log-linear modeling techniques to assess the influence of low-pass filtering, shaped noise, presentation level, and consonant position. Ten normal-hearing listeners were presented consonant-vowel (CV) and vowel-consonant (VC) syllables containing the vowel /a/. Stimuli were presented in quiet and in noise, and were either filtered or broadband. The noise was shaped such that the effective signal level in each 1/3 octave band was equivalent in quiet and noise listening conditions. Three presentation levels were analyzed corresponding to the overall rms level of the combined speech stimuli. Error patterns were affected significantly by presentation level, filtering, and consonant position as a complex interaction. The effect of filtering was dependent on presentation level and consonant position. The effects stemming from the noise were less pronounced. Specific confusions responsible for these effects were isolated, and an acoustical interaction is suggested, stressing the spectral characteristics of the signals and their modification by presentation level and filtering.

The role of auditory feedback in the vocalizations of cats.

The vocalizations of deaf cats were compared with those of littermate hearing controls at 30 days, 50 days, 1 year and 3 years of age. At all ages, deaf cats called more loudly than hearing animals. At 30 days, 50 days, and 3 years, deaf cats called about twice as loudly as hearing animals while at 1 year the calls of the deaf animals were approximately 6 times louder than those of the hearing littermates. Analysis of variance revealed significant differences in call loudness between deaf and hearing animals at 30 days, 1, and 3 years. Deaf and hearing animals did not differ in rate of calling or in the duration of individual vocalizations at 30 days, 50 days, and 1 year. At 3 years, the calls of the deaf animal were shorter than those of the hearing control. The calls of deaf animals were less variable than those of hearing animals at 30 days, 50 days, and 3 years. There was a tendency for the fundamental frequency of the calls of deaf animals to be higher than that of hearing animals at 30 days, 50 days, and 1 year. These results document the importance of auditory feedback in the regulation of feline vocalization.

Musical empathy (Einfuhling).

In this paper an "alpha-effect" is defined as a plethysmograph amplitude increase to the hearing of music concurrently with strong affinity for music, pleasurable feeling and reported empathy. Based on this definition a hypothetical model of empathy to music is formulated and the psychophysiological alpha-effect mechanism is related to the processes of empathy and cognitive attribution. In order to understand the psychophysiological mechanism of the alpha-effect, a network is proposed made up of several physiological processes with feedback circuits and feedback circuits at both the sensory and physiological level, and at the cognitive and psychological level. It was aimed also to give a theoretical account of the efficacy of music and to explicate the underlying psychophysiological mechanisms of that efficacy. The model may also help clinical psychologists who want to use music as a therapeutic tool in arranging optimal programs suited to the individual needs, experience, and background of a patient.

A computer program for estimating thresholds by means of Wetherill's Up-Down Transformed Response Rule (UDTR).

A Fortran IV computer program is presented which allows for automatic estimation of thresholds on an S-shaped psychometric curve by means of Wetherill's Up-Down Transformed Response Rule (UDTR). The efficiency and asymptotic properties of these rules are discussed and illustrated. The main program is in the form of a keyboard portable tutorial which calls the main decision-making subroutine. The subroutine can be detached from the tutorial. Only a single call with seven parameters is required to reach the subroutine. The program is particularly useful in forced-choice procedures.

Some effects of spectral shaping on recognition of speech by hearing-impaired listeners.

The effects of spectral shaping on speech recognition were investigated for hearing-impaired listeners with flat and steep audiometric configuration. Three frequency responses were tested: uniform frequency gain, high pass filtering, and a response shaped relative to each subject's loudness discomfort level curve. Speech-recognition performance was measured at four levels (from 80 to 95 dB SPL) using nonsense syllable (NST) and synthetic sentence (SSI) tests, presented against a background of "cafeteria noise." No significant differences in performance on the NST were observed between the two subject groups across all spectral shapes (frequency response) and presentation levels. On the SSI, performance of subjects with flat audiometric configuration was highest using the uniform frequency response, while performance of listeners with steep configuration was poorest for the uniform response. The recognition data were compared with predictions of relative performance using a modification of the Articulation index (AI). The AIs provided accurate estimates of relative performance across spectral shapes but were not consistent with relative performance as a function of presentation level. The results indicate that the selection of spectral shape for optimal performance is influenced by the particular speech task used to test recognition and also suggest that, with further validation, the AI may provide an objective technique for selecting optimal spectral shape.

Use of digitized speech materials in audiological research.

Computer methods, based on the theory and application of signal processing, combined with numerical methods for simulating mathematical processes, facilitate greater objectivity in most aspects of speech intelligibility testing, including specification of the stimuli, control of the tests, evaluation of the responses, corrective feedback, and automatic interpretation. This paper discusses several basic issues in digital signal processing, and also describes the application of computer-aided procedures for recording and delivery of speech materials for audiologic research. Examples of the use of computer procedures for manipulation of digitized stimuli demonstrate the increased efficiency and versatility of these procedures compared to more conventional tape recording methods. In addition, the use of digitized recordings allows more reliable specification of speech levels than conventional calibration methods involving observations of signal peaks on a VU-meter.

Visual and auditory information processing in children and adults.

Children of three ages were compared with adults in a recognition experiment requiring continuous processing of information. The growth in precision for visually presented words is steeper than for auditorially presented words, largely because the former are harder for the first graders and, to a lesser extent, for the third graders. In adults, visual processing of information is at least as good as auditory. The use of receiver operating characteristic curves in describing the data permit greater precision in estimating the capacity of the individual subjects and are particularly useful since the errors of failure to recognize were different from ordinary errors of false recognition, and they occurred in large numbers.