A Self-Calibration Stitching Method for Pitch Deviation Evaluation of a Long-Range Linear Scale by Using a Fizeau Interferometer

An interferometric self-calibration method for the evaluation of the pitch deviation of scale grating has been extended to evaluate the pitch deviation of the long-range type linear scale by utilizing the stitching interferometry technique. Following the previous work, in which the interferometric self-calibration method was proposed to assess the pitch deviation of the scale grating by combing the first-order diffracted beams from the grating, a stitching calibration method is proposed to enlarge the measurement range. Theoretical analysis is performed to realize the X-directional pitch deviation calibration of the long-range linear scale while reducing the second-order accumulation effect by canceling the influence of the reference flat error in the sub-apertures’ measurements. In this paper, the stitching interferometry theory is briefly reviewed, and theoretical equations of the X-directional pitch deviation stitching are derived for evaluation of the pitch deviation of the long-range linear scale. Followed by the simulation verification, some experiments with a linear scale of 105 mm length from a commercial interferential scanning-type optical encoder are conducted to verify the feasibility of the self-calibration stitching method for the calibration of the X-directional pitch deviation of the linear scale over its whole area.

Song imitation in congenital amusia: Performance partially facilitated by melody familiarity but not by phonetic content

Congenital amusia is a neurogenetic disorder of pitch perception that may also compromise pitch production. We explored whether vocal imitation of song in amusia is influenced by melody familiarity and phonetic content. Thirteen Mandarin-speaking amusics and 13 matched controls imitated novel song segments with lyrics and on the syllable /la/ while their output was recorded. Eleven out of these participants in each group also imitated segments of a familiar song. Subsequent acoustic analysis was conducted to measure pitch and timing matching accuracy. While amusics’ performance was facilitated by melody familiarity in terms of pitch interval deviation, signed interval deviation and number of contour errors, they showed compromised performance compared to controls in absolute pitch deviation, number of pitch interval errors, duration difference, interonset interval difference, and number of time errors in both familiar and novel song conditions. The presence of lyrics did not affect either group’s performance substantially. While a stronger relationship between music perception and novel melody imitation was observed in amusics as opposed to familiar melody imitation, controls showed the opposite pattern. We discuss the implications of the study in terms of music familiarity, memory demands, the relevance of lexical information and the link between perception and production.

Making of Intelligent Simulation Experiment of Sound Velocity Measurement

Ultrasound is used as the wave source for the sound velocity measurement experiment. Ultrasonic wave is used to form standing wave in the reflection interval, the position of two adjacent wave anti nodes is used to determine the half wavelength, and the sound velocity in the experimental state is measured. The specific experimental apparatus applies a spiral structure. The hand-wheel rotates through one cycle and the ultrasound emitter moves 1mm accordingly. Therefore, the circumference of the drum-wheel driven by the hand-wheel is equally divided into 100 scales, each scale is for one grid, and a spin of one grid is one percent of 1mm, thus the accuracy can be 0.001mm. But there usually exists half pitch deviation because of the clockwise and counterclockwise rotation of the drum wheel clockwise and counterclockwise usually produces half pitch. For the sound velocity measurement experiment it is unacceptable to rotate the drum-wheel at different directions back and forth. In order to avoid this nuisance, we propose a computer-based simulation experiment system and this system can help to obtain a higher precision which is up to four significant digits when compared to the practical experiment. This simulation system can effectively avoid operational mistakes by the experimenter. The experimental data henceforth will be of ideal precision. This system is also capable of repetitive operation which can make up for the deficiency of practical experiments.

Effects of Three Common Choral Performance Movement Conditions on Acoustic and Perceptual Measures of Choral Sound

The purpose of this investigation was to examine the effects of three commonly observed choral singer performance conditions (no movement, slight swaying, full-body swaying) on acoustic and perceptual measures of choral sound. We audio recorded an established university choir ( N = 29 singers) performing a memorized piece while viewing the same conductor video and participating in one of the three performance conditions. We analyzed data through long-term average spectrum (LTAS), overall pitch deviation, and singer and listener (singer-listeners, expert-listeners) perceptions. LTAS results showed significant differences ( p < .001) in spectral energy between all three conditions. The full-body swaying condition averaged a noticeable difference of 2.50 dB across the spectrum when compared to the other two conditions. Pitch analysis indicated the least overall pitch deviation during the slight swaying condition (−27.67 cents) and the most pitch deviation during the no-movement condition (−58.31 cents). Results indicated singer and singer-listener preferences for the full-body swaying condition and expert-listener preferences for the slight swaying condition. We discuss results in terms of future research and practical application for choral music educators.