• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1271-1278
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• 2007

A novel frequency multiplier using composite right/left-handed transmission line is proposed. The left-handed transmission line in the proposed frequency multiplier suppresses the fundamental component($f_0$), while the composite right/left-handed ${\lambda}/4$ open stub diminishes unwanted harmonics. Due to the combination of the left-handed transmission line and composite right/left-handed ${\lambda}/4$ open stub, the only desirable multiplied frequency component such as 3 $f_0$ and 4 $f_0$ are obtained at the output port excellently. For the example of the proposed design, frequency multipliers are designed at 1 GHz of $f_0$ and measured. The measured output power of 3 $f_0$ and 4 $f_0$ is -5.67 dBm and -6.43 dBm, respectively, when the fundamental input power was 0 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.513-520
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• 2003

In this paper, a novel design concept of frequency doubler using feedforward technique and DGS microstrip line is proposed. The feedforward loop plays a role of fundamental frequency suppression and DGS microstrip line suppresses over the 3rd order harmonic components. By using this new concept, the high suppression for the undesired signals could be achieved easily. The proposed technique is experimentally demonstrated in 1.87 GHz-to-3.74 GHz frequency doubler. The output power of -3 dBm at the frequency of 3.74 GHz(2f$\_$0/) is measured with 42.9 dB suppression of the fundamental frequency signal(f$\_$0/), 20.2 dB suppression of the 3rd harmonic signal(3f$\_$0/) and B9.7 dB suppression of the 4th harmonic signal(4f$\_$0/). The conversion loss of -2.34 dB ∼ -5.8 dB at the bandwidth of 100 MHz, the phase noise of -97.51 dB/Hz(＠10 kHz) were measured.

• Speech Sciences
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• v.15 no.4
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• pp.147-157
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• 2008

Habitual speaking fundamental frequency (sF0) plays an important role in determining the voice classification, which can be presented differently depending on the vocal fold length and language habits. The purpose of this study, therefore, was to compare the differences in sF0 for voice classification and closed quotient between speaking and singing. Seventeen singers (7 sopranos, 5 tenors, 5 baritones, mean age 25.1 years) with no evidence of vocal folds pathology were participated. sF0 and closed quotient (CQ) both in speaking and in singing (A3-A5 with soprano, A2-A4 with tenor and baritone) were measured using SPEAD program and electroglottography. No significant differences were observed for sF0 between tenor and baritone groups (p> 0.05). However, CQ in singing was significantly different among three groups (p< 0.05), but CQ in speaking was not (p> 0.05). Furthermore, CQ was significantly different with both soprano (p< 0.01) and tenor groups ((P= 0.02) whereas baritone group revealed there is no difference when compared between speaking and singing. No significant differences in sF0 between tenor and baritone participants may result from decision-making for voice classification by experience and should measure sF0 before determining the voice classification.

• Speech Sciences
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• v.7 no.1
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• pp.217-232
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• 2000

In this study, I investigate the role of post-consonantal fundamental frequency (F0) as a cue for automatic distinction of types of Korean stops and affricates. Rather than examining data obtained by restricting contexts to a minimum to prevent the interference of irrelevant factors, a relatively natural speaker independent speech corpus is analysed. Automatic and statistical approaches are adopted to annotate data, to minimise speaker variability, and to evaluate the results. In spite of possible loss of information during those automatic analyses, statistics obtained suggest that vowel F0 is a useful cue for distinguishing manners of articulation of Korean non-continuant obstruents having the same place of articulation, especially of lax and aspirated stops and affricates. On the basis of the statistics, automatic classification is attempted over the relevant consonants in a specific context where the micro-prosodic effects appear to be maximised. The results confirm the usefulness of this effect in application for Korean phone recognition.

• Phonetics and Speech Sciences
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• v.12 no.4
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• pp.1-8
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• 2020

Traditionally it has been understood that the aspirated and lenis stops in Seoul Korean are distinguished primarily by voice onset time (VOT) and secondarily by other cues such as the fundamental frequency (F0) of the following vowel. However, recent studies on stop production have shown that the aspirated and lenis stops are currently merging in VOT and that they are now differentiated primarily by F0. In the present study, we examined whether the currently reported change in the production domain would be also found in the perception domain. To this end, an auditory identification task was conducted using speech materials of varying VOT and F0 values with young and older male and female Seoul listeners. Results revealed that all listener groups used both VOT and F0 to distinguish the lenis vs. aspirated stops but they used the F0 cue more reliably than the VOT cue in discriminating the stop contrast. The effects of gender and age were found only in the VOT cue (i.e., not in the F0 cue), with the greatest VOT cue weight in older males and the smallest in young females, which is in line with recent production studies.

• Phonetics and Speech Sciences
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• v.1 no.3
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• pp.73-85
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• 2009

This paper introduces the technique of synthesizing and evaluating human utterances with exaggerated or atypical prosody. Prosody exaggeration can be implemented by manipulating either the fundamental frequency (F0) contour, the segmental durations, or the intensity contour of an utterance. Of these three prosodic elements, two or more can be exaggerated at the same time. The algorithms of synthesis and evaluation were suggested. Learner utterances exaggerated in each of the three prosodic features were evaluated with respect to their original native versions in terms of the differences in their F0 contours, the segmental durations, and the intensity contours. The measure of differences was the Euclidean distance metric between the matching points in their F0 and intensity contours. The measure was calculated after the exaggerated learner utterances were aligned by the segments and rendered identical to their native version in terms of their segmental durations. For the evaluation of the segmental durations, no prior modifications were made in durations and the same measure was used. The results from the pilot experiment suggest the viability of this measure in the evaluation of learner utterances with atypical prosody with respect to their native versions.

• Phonetics and Speech Sciences
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• v.5 no.1
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• pp.81-90
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• 2013

During adolescence the mutational period is characterized by the changes in the laryngeal structure, the length of the vocal cords, and a tone of voice. Usually, adolescents at 15 or 16 reach the voice of adults but the mutational period is sometimes delayed. Therefore, studies on the voice of adolescents between 16 ~ 18 right after the mutational period are required. Accordingly, this paper attempted to provide basic data about the normal standard for patients with voice disorders during this period by evaluating the vocal characteristics of males and females between 16 ~ 18 with an objective device bycomparing and analyzing them by sex and age. The study was conducted on a total of 60 subjects composed of each 10 subjects of each age. The vocal analysis was conducted by MPT (Maximum Phonation Time) measurement, sustained vowels and sentence reading. As for /a/ sustained vowels, fundamental frequency, hereinafter referred to as $F_0$, jitter, shimmer, noise-to-harmonic ratio, hereinafter referred to as NHR were measured by using the Multi-dimensional voice program (MDVP) among the Multi-Speech program of Computerized Speech Lab (Kay Elemetrics). The sentence reading, mean $F_0$, maximum $F_0$ and minimum $F_0$ were measured using the Real-Time Pitch (RTP) Model 5121 among the Multi-Speech program of Computerized Speech Lab (Kay Elemetrics). As a result, according to sex, there were statistically significant differences in $F_0$, jitter, shimmer, mean $F_0$, maximum $F_0$, and minimum $F_0$; and according to age, there were statistically significant differences in MPT. In conclusion, the voice of the adolescents between 16 ~ 18 reached the maturity levels of adults but the voice quality which can be considered on the scale of voice disorders showed transition to the voice of an adult during the mutational period.

• MALSORI
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• no.52
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• pp.49-60
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• 2004

The purpose of this paper was to evaluate the effect of hearing level on fundamental frequencies in children. Participants totaled sixty children divided by three groups: congenitally deafened children with cochlear implantation(CI), congenitally deafened children with hearing aids(HA), and children with normal hearing(NH). Fundamental frequencies were measured during the sustained phonation of a vowel /a/. There was statistically significant difference of fundamental frequencies across the groups(p<.01). In post hoc analysis, HA and NH group showed statistically significant difference, but CI group didn't showed significant differences with two groups. In correlation analysis between F0 and the chronological age, there were significant negative tendencies in CI and NH group, but not in HA group. The characteristics of fundamental frequency in CI group were found similar to NH group than HA group in this study. Therefore the results of this study suggest that the hearing level is one of the influencing factors to the fundamental frequency of children.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.8 s.111
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• pp.725-731
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• 2006

A novel design of frequency multiplier using a feedforward technique and a defected ground structure(DGS) is proposed. The feedforward loop in the proposed frequency multiplier suppresses the fundamental component $(f_0)$, the dumb-bell or spiral shaped DGS diminish unwanted harmonics such as second, third and fourth. Due to the combination of the feedforward structure and the DGS, only the multiplied frequency component$(2f_0,\;3f_0,\;4f_0)$ appears at the output port and the other unwanted components are suppressed excellently. The frequency multiplier is designed at 1 GHz $(f_0)$, by the proposed technique and measured. The measured output power of $2f_0,\;3f_0$ and $4f_0$ is -2.59 dBm, -5.36dBm and -4.57dBm, respectively, when the input power is 0dBm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2203-2208
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• 2011

This study was to examine the change of vowel acoustic characteristics of the temporomandibular joint disorder patients by maintaining normal vocalization pattern of the temporomandibular joint through increasing the range of motion, that was, the oral cavity sonorant cavity of the temporomandibular joint, related to vowel articulation through temporomandibular training using the physical therapy. The subjects of this study were 3 male adults in 20-30s that were diagnosed with temporomandibular joint disorder. As a result of conducting temporomandibular training program using the physical therapy, the $1^{st}$ Formant Frequency(F1), $2^{nd}$ Formant Frequency(F2), and Fundamental Frequency(F0) of the temporomandibular joint disorder patients were increased compared to before and this showed the change of the $1^{st}$ Formant Frequency(F1) related to the open mouth grade of a vowel, as well as the $2^{nd}$ Formant Frequency(F2), and Fundamental Frequency(F0) related to the front-back of a vowel which shows the relationship between the temporomandibular joint, vowels and voice calculation.