Determination of Peierls stress from acoustic harmonic generation

The interaction of acoustic waves with dislocations leads to aperiodic oscillations in the magnitude of the acoustic nonlinearity parameter β as a function of the acoustic drive amplitude σ _ampl. The magnitude and spacing of the oscillations depend on the value of the Peierls stress. A least-square curve fit of the β(σ _ampl) equation to experimental data taken of 99.999% pure aluminum monocrystals oriented for wave propagation along the [1?0?0] crystal axis yields the value 6.2?×?10⁴?Pa for the Peierls stress. The value is consistent with the smallest values reported in the literature for aluminum where for both theoretical and experimental studies the reported values range over three orders of magnitude.     

Masking of tones by tones and of noise by noise

Using a two-alternative temporal forced-choice technique, two binaural detection experiments were performed. In the first, the detectability of a 250-Hz 128-msec tonal signal masked by a gated 70-dB SPL tone of the same frequency and duration was measured as a function of the level of the signal, the phase angle at which the signal was added to the masker, and the interaural phase difference of the signal. In the second experiment, the signal was a wideband (100-3,000 Hz) 128-msec Gaussian noise masked by a continuous Gaussian noise of the same bandwidth and coherent with the signal. The detectability of this noise signal was measured as a function of the same variables investigated in the first experiment. In both experiments detectability was found to follow a simple energy- or power-detection model when the interaural phase difference was 0 deg. When the interaural phase difference was 180 deg, the function relating the signal level required for a constant level of performance to the signal-masker phase angle is such that neither the Webster-Jeffress hypothesis nor Durlach’s E-C model accounts for the data. The data are reasonably well fit by a model proposed by Hafter and Carrier.     

Diotic and dichotic frequency recognition in a single-interval temporal interference procedure

The frequency discriminability of a 70-dB SPL, 20-msec test tone followed 5 msec later by an equally intense 500-msec, 800-Hz interference tone was studied in a single-interval procedure for one diotic condition and three dichotic conditions. The test tone (T) and interference tone (I) were presented the same to both ears (ToIo, diotic condition) and in three dichotic conditions: (1) the interference tone was presented to the right ear (R) and the test tone to the left ear (L) (T_LI_R), (2) the interference tone was presented the same to both ears and the test tone to one ear (TmIo), and (3) the interference tone was presented the same to both ears and the test tone to both ears with an interaural phase reversal (TπIo). The threshold value for test tone frequency discrimination in the diotic temporal interference condition was approximately six times greater than that obtained without an interference tone. The three dichotic temporal interference conditions yielded essentially equivalent threshold values which were approximately 2.4 times that obtained when the test tone was presented without an interference tone. Therefore, although never equaling interference-free conditions, dichotic test tone presentations can improve frequency recognition relative to diotic conditions at intensities well above threshold. It is postulated that this improvement may be due to the spatial separation of test and interfering tones, rather than to possible differences in diotic vs. dichotic subjective intensities. Dichotic-diotic frequency recognition differences did not occur when a 100-msec interval separated the test and interfering tone or when the interfering tone preceded the test tone.     

Multivariate statistics and three-dimensional graphics

This paper describes the process by which a system of three-dimensional computer-generated graphics was developed for use by students and researchers in analyzing multivariate psychological data. Examples of the application and use of the system in analyzing factor analytic and discriminant analysis data are presented. Details on the operation of the system are also included.     

A simulated “cocktail party” with up to three sound sources

Listeners identified spoken words, letters, and numbers and the spatial location of these utterances in three listening conditions as a function of the number of simultaneously presented utterances. The three listening conditions were a normal listening condition, in which the sounds were presented over seven possible loudspeakers to a listener seated in a sound-deadened listening room; a one-headphone listening condition, in which a single microphone that was placed in the listening room delivered the sounds to a single headphone worn by the listener in a remote room; and a stationary KEMAR listening condition, in which binaural recordings from an acoustic manikin placed in the listening room were delivered to a listener in the remote room. The listeners were presented one, two, or three simultaneous utterances. The results show that utterance identification was better in the normal listening condition than in the one-headphone condition, with the KEMAR listening condition yielding intermediate levels of performance. However, the differences between listening in the normal and in the one-headphone conditions were much smaller when two, rather than three, utterances were presented at a time. Localization performance was good for both the normal and the KEMAR listening conditions and at chance for the one-headphone condition. The results suggest that binaural processing is probably more important for solving the “cocktail party” problem when there are more than two concurrent sound sources.     

Simulation of motor-neuronal networks

This research develops a theoretical connectionist-type model of the operation of the human motor system. The model includes the operation of the cerebral cortex, pons, spinal cord, and muscles. It emphasizes the parallel passage of neuronal signals, the integration of multiple signals within nuclei, and the modulation of signals as a result of sensory input. A redundant Fast Fourier Transform (FFT) procedure that analyzes EEG signals by a method similar to the one used by pontine nuclei is described.     

Assessing the Unidimensionality of Trait Reactance Using a Multifaceted Model Assessment Approach

This study employed a multifaceted model assessment approach to investigate the dimensionality and nomological network of a popular measure of trait reactance, the Hong Psychological Reactance Scale (HPRS; Hong &; Page, 1989 Hong, S.-M., &; Page, S. (1989). A psychological reactance scale: Development, factor structure and reliability. Psychological Reports, 64, 1323–1326.[Crossref], [Web of Science ®] , [Google Scholar]). To address confusion regarding the scoring and modeling of the HPRS as well as its limited external validity evidence, we tested competing factor models, diagnosed model–data misfit, examined relationships between competing factor models and key personality traits, and cross-validated the results. Confirmatory factor analytic results supported modeling the HPRS via a bifactor model and, when this model was applied, trait reactance was negatively related to agreeableness, conscientiousness, and conformity, and positively related to entitlement, as expected. However, we also demonstrated the consequences of championing a 1-factor model by highlighting differences in relationships with external variables. Specifically, although modeling the HPRS scores with the bifactor model resulted in greater model–data fit than the 1-factor model, relationships with external variables based on the 2 models differed negligibly. Moreover, bifactor statistical indexes indicted that scores were essentially unidimensional, providing some support that HPRS scores can be treated as unidimensional in structure. Implications for using and scoring the HPRS are discussed.     

Pitch perception in chinchillas (Chinchilla laniger): stimulus generalization using rippled noise

Rippled noises evoke the perception of pitch in human listeners. Infinitely iterated rippled noise (IIRN) is generated when wideband noise (WBN) is delayed, attenuated, and added to the original WBN through either a positive (+) or a negative (-) feedback loop. The pitch of IIRN[+] is matched to the reciprocal of the delay, whereas the pitch of IIRN[-] for the same delay is an octave lower. Chinchillas (Chinchilla laniger) were trained to discriminate IIRN[+] with a 4-ms delay from IIRN[+] with a 2-ms delay and then tested in a stimulus generalization paradigm with IIRN[+] at delays between 2 and 4 ms. Systematic gradients in behavioral response occurred along the dimension of delay, suggesting that a perceptual dimension corresponding to pitch exists for IIRN[+]. Behavioral responses to IIRN[-] test stimuli were more variable among chinchillas, suggesting that IIRN[-] did not evoke similar pitches relative to IIRN[+]. Systematic gradients in behavioral response were observed when IIRN[-] test stimuli were presented in the context of other IIRN[-] stimuli. Thus, other perceptual cues such as timbre may dominate the pitch cues when IIRN[-] test stimuli are presented in the context of IIRN[+] stimuli.     

Pitch perception

This article is a review of the psychophysical study of pitch perception. The history of the study of pitch has seen a continual competition between spectral and temporal theories of pitch perception. The pitch of complex stimuli is likely based on the temporal regularities in a sound’s waveform, with the strongest pitches occurring for stimuli with low-frequency components. Thus, temporal models, especially those based on autocorrelationlike processes, appear to account for the majority of the data.