Peak Tone Research Articles

A 28-nm 10-b 2.2-GS/s 18.2-mW Relative-Prime Time-Interleaved Sub-Ranging SAR ADC With On-Chip Background Skew Calibration

This article presents a relative-prime-based time-interleaved (RP TI) sub-ranging successive-approximation register (SAR) analog-to-digital converter (ADC) with on-chip background skew calibration. The proposed calibration aligns the sampling time of every fine ADC (F-ADC) to that of a particular coarse ADC (C-ADC) that works as a reference ADC. To avoid the unwanted calibration tone from the reference ADC, the C-ADC is also time-interleaved to make all samples undergo the same kick back. By setting the numbers of the time-interleaved channels of the C-ADCs and F-ADCs in a relative-prime relationship, every C-ADC can be evenly shared by every F-ADC; thus, the timing skews between the interleaved sub-ADCs are calibrated by adjusting the sampling edges of every F-ADC to the particular C-ADC working as a reference ADC. An 18-channel TI 10-bit 2.2-GS/s SAR ADC was implemented as a prototype with 28-nm CMOS. Owing to the proposed on-chip background skew calibration, the peak tone by skew was reduced by 23 dB from -40 to -63 dB, which corresponds to the residual skew reduction from 1.6 ps to 113 fs near the Nyquist input. Thus, the prototype ADC achieved a spurious free dynamic range (SFDR) over 52.8 dB and a signal-to-noise-and-distortion ratio (SNDR) over 44.9 dB with 18.2-mW power consumption, which leads to a Walden figure-of-merit (FoM) of 57.8 fJ/conversion-step.

Control of High Subsonic Cavity Flow Using Plasma Actuators

Localized arc filament plasma actuators were used to control pressure fluctuations in a cavity with a depth of 12.7 mm and length-to-depth ratio of 4.86. The rear wall of the cavity is inclined 30 deg with respect to the upstream flow, and the cavity length is 61.7 mm. Five actuators were uniformly distributed along the span of the cavity, 1 mm upstream of the cavity leading edge. Experiments were conducted in a flow with a Mach number of 0.6 and a Reynolds number based on the cavity depth of . Forcing was conducted quasi-two-dimensionally (all actuators operated in phase) and three-dimensionally (actuators operated out of phase). The objective of the research was twofold: first, to demonstrate that the peak tone as well as the broadband pressure fluctuations can be suppressed in a strongly resonating cavity, and second, the resonance can be re-established and the peak tone as well as the broadband pressure fluctuations can be amplified in a weakly resonating cavity. Time-resolved pressure and particle-image-velocimetry measurements were used to assess the effectiveness of the actuators and to explore the physics of the flow. Although both quasi-two-dimensional and three-dimensional controls were successful in controlling the flow, the control was less sensitive to forcing frequency change in the latter in achieving the first objective. The results also showed that, although there are many forcing frequency options in achieving the first objective, the options are limited to frequencies near the dominant (even though weak) Rossiter modes in re-establishing the feedback in a weakly resonating cavity.

Effect of Harmonic Features for Designing Product Sound Quality

In the design of emotional qualities, which are evaluated by the customer's subjective impressions, feelings and emotions, such as a feeling towards product sound, a designer needs to find the design factors that affect the emotional quality and determine the characteristics of their effects. The authors previously proposed a method for extraction of potential emotional factors by analyzing human sensitivity towards unexplored design and applied the method for designing product sound quality. From the result using vacuum cleaners as a case study, the authors found that the existence of prominent peak tones in sound around 500Hz has the potential to improve sound quality. However, prominent peak tones are usually regarded as a factor of annoyance. In this paper, we propose an indicator for adjusting the frequency and level of peak tones to improve a product sound quality. We have assumed that the harmonic features of peak tones in noise can be used as the indicator. We created vacuum cleaner sounds having three peak tones whose harmonic features such as tonal consonance and modality are different. To evaluate the effectiveness of the harmonic features, we conducted a pairwise comparison-based sensory evaluation with two groups of participants, one consisting of those who play some musical instrument and the other of those who do not. From the experiment, we found that the peak tone harmonic features can be perceived by both groups of participants and significantly decrease their annoyance at vacuum cleaner sounds.

Where is the expressivity in singing?

When computers convert music scores to sounding music, performances void of musical expression typically emerge, mostly perceived as musical disasters. This is a striking illustration of the importance of the contributions of musicians. Excellent tools for exploring these contributions are synthesized performances and/or processing of real performances. In the 1970s, the KTH music group started to formulate rules for music performance, now integrated into the KTH Director Musices performance grammar. Some principles underlying its performance rules can be identified: (1) marking of phrase structure, (2) increasing contrasts along acoustic parameters, and (3) emphasizing important and/or less expected notes. These principles can be observed also in phonetics and speech prosody. Also the acoustic codes used for these principles in music performance are similar to those used in speech. Just as pitch is raised in agitated speech, singers have recently been found to increase contrast along the pitch dimension by sharpening the peak note in agitated phrases. In a recent experiment, audio processing software was used to quasi-correct the intonation of the peak tone in a handful of examples sung by a professional baritone singer. A listening test indicated that the sharpening added to the expressivity of the performance.

Microvascular tone in a skeletal muscle of spontaneously hypertensive rats.

We studied the degree of arteriolar smooth muscle constriction in the spinotrapezius muscle microcirculation of spontaneously hypertensive rats and their normotensive controls, Wistar-Kyoto rats. The constriction was expressed in the form of a nondimensional tone as the difference between steady state and dilated diameter (after papaverine treatment) divided by the dilated diameter. Both animal strains showed on average a progressive increase of tone toward the more distal arterioles, with a peak tone being reached in the transverse arterioles. Tone values in the hypertensive animals were consistently elevated. The number of arterioles that had more than 5% tone (so-called responder arterioles) was higher in the hypertensive animals. These studies suggest that, besides the anatomical adjustments documented earlier in our laboratory in the arteriolar network of this muscle, functional adjustments in the form of an elevated microvascular tone are associated with the elevated resistance in spontaneously hypertensive rats.

Electrical slow waves and tone of guinea-pig isolated trachealis muscle: effects of drugs and temperature changes.

1 Simultaneous recordings of electrical and mechanical activity have been made from guinea-pig isolated trachealis muscle. Electrical activity was recorded both by extracellular and intracellular techniques.2 Extracellular studies showed that the spontaneous development of tone was accompanied by electrical slow waves which frequently exhibited pronounced waxing and waning. Intracellular recording confirmed the discharge of these slow waves in individual cells. Extracellularly-recorded slow waves were often of greatest amplitude while the tissue was developing rather than maintaining tension. Some tissues became electrically quiescent on reaching peak tone.3 Cooling to 27.5 degrees C caused some relaxation. Slow wave amplitude and frequency fell, slow waves eventually being abolished. Subsequent rapid rewarming initially evoked a more profound relaxation. An intense discharge of slow waves then occurred as the tension rapidly rose again towards the pre-cooling value.4 Sodium nitrite, (-)-isoprenaline, adenosine and adenosine triphosphate (ATP) each evoked relaxation and reduced the frequency and amplitude of slow waves. High concentrations of these agents often abolished slow waves. The actions of these drugs were reversible.5 Treatment with methoxyverapamil (D600) 1 mumol/l for 15 min abolished slow wave activity but only evoked partial relaxation of the tissue.6 Acetylcholine, histamine and tetraethylammonium (TEA) each evoked contraction, but TEA was unique in consistently promoting slow waves and (in high concentration) spike activity. Spasm evoked by acetylcholine and histamine did not usually involve the initiation or promotion of slow waves. Indeed in appropriate concentration these two agents always suppressed slow wave activity. The actions of the spasmogens were reversible.7 It is concluded that the smooth muscle cells of the trachealis are electrically coupled. While co-ordinated slow wave activity is associated with the spontaneous development of tension in trachealis, it may not be necessary for the maintenance of the major part of the spontaneous tension exhibited by the tissue or for the spasm evoked by histamine or acetylcholine. Slow wave promotion by TEA suggests that the tissue may have a high resting potassium conductance which normally attenuates the slow waves. Slow waves may be suppressed by a variety of drugs acting by different mechanisms. Since D600 suppresses slow waves of the trachealis the mechanisms underlying the waves may be similar to those underlying spike activity in other smooth muscles.

Axial fan noise with modulated stator blade spacing

This paper describes the investigations carried out to examine whether unevenly spaced stator blades can be advantageously used to reduce the blade passing frequency tone generated by rotor wake interaction with the stators. Experiments were carried out on a single stage axial fan of 305‐mm diameter with 18 rotor blades followed by 19 stator blades at one‐fifth and 2 rotor blade chord distances. The spacings between the stator blades were varied with 5° and 10° modulation amplitudes. Farfield noise measurements made inside an anechoic test cell with symmetric and modulated blades showed significant changes in the directionality of the blade passing frequency tone with no apparent reductions in the peak tone levels. The generation and propagation of acoustic modes by rotor‐stator interaction for the case of modulated stator blades were theoretically examined in the light of the experimental results. Although the modes generated by symmetrical stators were attenuated, the sound energy was distributed to the additional modes thus causing no drastic reduction in the radiated energy.