Clear Harmonic Structure Research Articles

Robust voice activity detection based on harmonic to noise ratio

A robust voice activity detection algorithm based on harmonic to noise ratio (HNR) is proposed. Harmonic to noise ratio is high in voice segments, because most of the voice energy distributes on the harmonic structure. However, it is unreliable or complicated to estimate the harmonic frequencies of noisy speech, and the HNR in full frequency band is not robust for environments with non-stationary band-limited noise. In this paper, several harmonic templates with fundamental frequency changing in log-scale step are used to match the wide-band voice harmonic structure, and the fundamental frequencies are not need to be estimated. To avoid the non-stationary band-limited noise, the contaminated frequencies are neglected automatically by frequency bin selection, which discards the harmonic and the noisy bins with the highest and lowest energy to keep the main clear harmonic structure. The final voice activity detection is based on the HNR of continuous frames, and it shows robust performance on several databases.

Vocal communication in the striped field mouse, Apodemus agrarius, in dyadic encounters and intraspecific cage groups

The aim of this research was to describe and analyse the vocal signals emitted by males and females of Apodemus agrarius in dyadic encounters and intraspecific cage groups. Most of the sounds recorded were in the context of agonistic behaviour. The sounds were classified into three main groups: The first group corresponded to calls with clear harmonic structure. They varied in frequency, duration and intensity. During attacks and fights, the calls were louder and with a higher dominant frequency (8.7±0.2 kHz) than those produced in response to opponent approach (4.4±0.07 kHz). The second group included relatively short harsh calls – with noise component but without clear harmonic structure. The third group of vocalizations corresponded to the calls resembling low clucks. They were characterized by a low dominant frequency, 1.0±0.01 kHz, and brief duration. The context and possible functions of the described calls are discussed.

Two new canyon-dwelling frogs from the arid sandstone Isalo Massif, central-southern Madagascar (Mantellidae, Mantellinae)

We describe two new mantellid frogs of the subfamily Mantellinae from the arid sandstone Isalo Massif, central southern Madagascar. The first - assigned to the genus Gephyromantis, subgenus Phylacomantis - is a stream frog living in open canyons and associated gallery forest, and is phylogenetically related to G. corvus and G. pseudoasper. It has a larger maximum SVL than G. corvus (43 mm vs. 38 mm in the examined males) and is featured by a mostly contrasted and lighter dorsal pattern. Its advertisement call also differs from that of G. corvus in having more numerous and slightly longer notes per call composed of seven to ten sub-units, a clear harmonic structure, and a wider frequency spectrum with a higher dominant frequency. The second new species belongs to the genus Mantidactylus, subgenus Brygoomantis. It shares morphological and life history similarities with species of the subgenus Ochthomantis, in having comparatively expanded fingertips and leading a rupicolous and scansorial life.

Voice quality after carbon dioxide laser and conventional surgery for T1A glottic carcinoma

The different types of small vocal fold tumor therapy allow the preservation of respiration and deglutition; the quality of phonation is the most important criterion for the patient. The aim of the study is to compare vocal function after treatment of T1a tumors by conventional and laser cordectomy. Fifty-seven male patients were included in the study: 27 underwent conventional cordectomy using an external approach, and 30 underwent an endoscopic microscopic laser cordectomy. Videolaryngoscopy was performed for each subject, and the maximal phonation time was measured. Spectrograms were recorded, and a perturbation analysis was performed if a clear harmonic structure was visible. Voices were perceptually rated by two experienced phoniatricians using the GRBAS scale. Even though a slightly better voice was found after conventional surgery throughout the data, no statistically significant difference was measured in the two groups. The data on voice outcome per se do not indicate the selection of one surgical approach over another.

On spectra of ionospheric conductivity variations during a heating experiment

Appearance of the harmonics in the spectrum of artificial emissions generated during heating experiments has been reported earlier. Usually, it relates with square modulation of HF powerful wave and distortion of this time dependence due to characteristic time of electron heating/cooling. In the EISCAT‐Heating experiment in November 1993, a quasi‐sinusoidal modulation regime was used. Observations show the clear harmonic structure in artificial emissions in this case too. In the present paper we discuss a generation of harmonics of a modulation frequency due to nonlinear dependence of value of the ionosphere conductivity disturbance from effective radiated power (ERP). A numerical model is used for calculations of the spectrum of the integral conductivity disturbance variation as a function of electron density profile and ERP. For the modulation frequency in the range of 1–100 Hz, the characteristic time of electron heating/cooling was neglected, and intensity ratios of the second and third harmonics to the fundamental frequency reach 0.4 and 0.15, respectively. For the modulation frequency 1375 Hz, time integration of the electron energy balance equation was used. The different characteristic time constants of the electron heating/cooling at different altitudes make the behavior of the intensity ratio and phase shift of the harmonics of the integral conductivity disturbance variations more complicated. The values of the harmonic amplitude ratio in this case decrease to 0.25 and 0.1.

On the distribution of polar electrostatic emissions and their relationships to auroral hiss and direction finding measurements of saucer emission in polar regions observed by Isis, Kyokko and Akebono satellites

Since 1976 a total of 3500 orbits of data from the Isis-1 and 2, Kyokko and Akebono satellites have been analysed to produce some new observational results about polar VLF and ELF emissions at Arctica and Antarctica. By mapping the distribution of the occurrence of the emissions in the polar regions the source of Electrostatic Ion Cyclotron (EIC) emissions has been located. 1. (1)The EIC emissions with clear harmonic structure at the local ion cyclotron frequency of wide V-shaped auroral hiss emissions were always located at altitudes about 3000 km above an auroral arc. 2. (2)Over 85% of EIC emissions were observed at the active auroral area of the night-side. 3. (3)Direction finding observations using the Akebono satellite showed that all sources of VLF saucers were located below the altitude of the satellite orbit.

A study of the power spectra of dPi's and Pi 2's

A study of the power spectra of dPi's observed between geomagnetic latitudes 64° and 54°N shows that they exhibit clear harmonic structure. The fundamental period is predominantly in the range 300–360 sec and linear harmonics are observed up to the 9th or 10th. The 53 events studied showed no latitude dependence of fundamental period, but it was clear in some cases that the spectral energy was redistributed among the harmonics at the lower latitude stations. A similar study of Pi 2's showed much less harmonic structure in their spectra. There is evidence of a relationship between the trigger which initiates the event and Kpindex (by inference solar wind intensity) and the results are interpreted as strong support for the view that dPi's are the complete manifestation of the nighttime impulsive event and that they are triggered, as transverse free oscillations, on the ‘last closed field lines’ in the premidnight sector of the magnetosphere. It is inferred that when they are observed at low latitudes it is due to the down-coming wave (transmitted across the meridian plane) causing forced oscillations of lower latitude lines of force. Secondary resonance at lower latitudes accounts for the change in spectral distributions observed and for the apparently unconnected Pi 2 spectral forms.

Anatomical and spectrographic analysis of the voice in disease: A report of five cases

Five cases are presented. One is a case of ventricular phonation of iatrogenic origin and the remaining four had undergone laryngectomy for carcinoma of the larynx. Points of interest are discussed, particularly the constant ventricular fold phonation of the first case and the clear harmonic structure present in the voice of one of the laryngectomy cases who has both esophageal speech and pharyngeal phonation.

The role of vocalization in the social behaviour of the northern elephant seal

The northern elephant seal breeds on islands off the coast of Mexico and California. It is a highly vocal species and during the breeding season vocalization plays an important role in the maintenance of the species' highly polygynous social organization. The importance of vocalization in this species is demonstrated by the presence in the adult male of a highly modified proboscis which appears to have no function other than the production of vocal threats. Observation of colour-marked individuals on San Nicolas Island, California, showed that females of a harem tend to remain in a given spot. Females of low dominance are often forced to move by the aggressive behaviour of more dominant females and their pups are likely to become lost and to be bitten by other females. The voice of the pup attracts the mother and stimulates the mother to suckle the pup. Observations in the field combined with spectrographic analysis of tape recordings reveal two main communicational and structural classes of vocalization, attraction calls and threat sounds. Attraction sounds (mother to pup) are unpulsed, of high and variable pitch, and show clear harmonic structure. Threat sounds (both female and male) have an opposite type of structure; they are highly pulsed, of low and steady pitch, are harsh, and lack clearcut harmonics. In general, pulse interval in the threat sounds tends to increase with body size. Among males, the resonance and volume of the clap-threat increases with the size and development of the proboscis. Hissing occurs in many tetrapods and probably preceded and facilitated the evolution of vocal cords and patterned sounds; in turn the extensive use of different sounds as a means of communication probably facilitated the evolution of social life in the vertebrates. It is of interest that yearlings use the hiss as a threat and some yearling threat sounds are structurally intermediate between a hiss and the common roaring type of threat.