• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.285-288
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• 2001

In the speech analysis, to estimate formant center frequencies exactly is very important. If we know formant frequencies, we can expect which pronunciation is uttered. Generally, the magnitude of first formant frequency in voiced speech is 10dB more than other formant frequency. So, the shape of voice signal in time domain is affected by mainly first formant. Therefore we can get first formant frequency roughly by using ZCR(Zero Cross Rate). In this paper, we proposed the improvement method to get first formant frequency by using ZCR. We did autocorrelation before getting ZCR. This procedure makes voice signal smooth so, first formant in voice signal is emphasized. As a result of this method, we got more exact ZCR and first formant frequency. Conventional method of formant estimate is done in frequency domain but proposed method is done in time domain. So, this is very simple.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2003년도 5월 학술대회지
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• pp.141-144
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• 2003

In this paper, we compared formant frequency extraction algorithms with various conditions, and show their performances. The formant frequency is the resonance frequency which is decided by the vocal tract characteristics. It is related with phonemes, or characteristics of the physical condition of the vocal track. Since the speech signal is influenced by both the sound source and the vocal tract, it is difficult to calculate the exact formant frequencies. Many studies on the formant frequency extraction had been executed already Besides, any new formant frequency extraction algorithm is hardly found recently.

• 대한후두음성언어의학회지
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• 제16권1호
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• pp.10-14
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• 2005

Background and Objectives : Vowels are characterized on the basis of formant patterns. The first formant(F1) is determined by high-low placement of the tongue, and the second formant (F2) by front-back placement of the tongue. The fundamental frequency(F0) of a soprano often exceed the normal frequency of the first formant. And the vocal intensity is boosted when F0 is high and a harmonic coincides with a formant. This is called a formant tuning. Experienced singers thus learned how to tune their formants over a resonable range by lowering the tongue to maximize their vocal intensity. So, the current study aimed to identify the formant tuning in one experienced soprano by comparing the first formants of vowel [i] in three different voice production : speech, ascending scale, and vocalize. Materials and Method : All voices recordings of vowel [i] in speech, ascending scale (from F4 note to A4 note), and vocalize(:Ridente la calam") were made with digital audio tape-corder in a sound treated room. And the captured data were analyzed by the long term average(LTA) power spectrum using the FFT algorithm of the Computerized Speech Lab(CSL, Kay elementrics, Model, 4300B). Results : Although the first formant of vowel [i] in speech was 238Hz, those of ascending scale [i] were 377Hz, 405Hz, 453Hz respectively in F4(349z), G4(392Hz), A4(440Hz) note, and 722Hz, 820Hz, 918Hz respectively in F5 (698Hz), G5(784Hz), A5(880Hz) note. In vocalize, first formants of [i] were 380Hz, 398Hz, 453Hz respectively in F4, G4, A4 note, and 720Hz, 821Hz, 890Hz respectively in F5, G5, A5 note. Conclusion : These results showed that the first formant of ascending scale and vocalize sustained higher frequency than fundamental frequency in high pitch. This finding implicates that the formant tuning of vowel [i] in ascending scale was also noted in vocalize.

• 말소리와 음성과학
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• 제6권4호
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• pp.133-139
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• 2014

This paper describes several approaches to transform a speaker's individuality to another's individuality using frequency warping between bilingual formant frequencies on different language environments. The proposed methods are simple and intuitive voice conversion algorithms that do not use training data between different languages. The approaches find the warping function from source speaker's frequency to target speaker's frequency on formant space. The formant space comprises four representative monophthongs for each language. The warping functions can be represented by piecewise linear equations, inverse matrix. The used features are pure frequency components including magnitudes, phases, and line spectral frequencies (LSF). The experiments show that the LSF-based voice conversion methods give better performance than other methods.

• 산업경영시스템학회지
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• 제37권1호
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• pp.26-32
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• 2014

Mental fatigue is inevitable in the workplace. Since mental fatigue can lead to decreased efficiency and critical accidents, it is important to manage mental fatigue from the viewpoint of accident prevention. An experiment was performed to evaluate mental fatigue using the formant frequency analysis of human voices. The experimental task was to mentally add or subtract two one-digit numbers. After completing the tasks with four different levels of mental fatigue, subjects were asked to read Korean vowels and their voices were recorded. Five vowel sounds of "아", "어", "오", "우", and "이" from the voice recorded were then used to extract formant 1 frequency. Results of separate ANOVAs showed significant main effects of mental fatigue on formant 1 frequencies of all five vowels concerned. However, post-hoc comparisons revealed that formant 1 frequencies of "아" and "어" were most sensitive to mental fatigue level employed in this experiment. Formant 1 frequencies of "아" and "어" significantly decrease as the mental fatigue accumulates. The formant frequency extracted from human voice would be potentially applicable for detecting mental fatigue induced during industrial tasks.

• 대한인간공학회지
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• 제32권1호
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• pp.139-144
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• 2013

Objective: The current study investigated a non-obtrusive measure for detecting physical fatigue based on the analysis of formant frequencies of human voice. Background: Fatigue has been considered as a main cause in industrial and traffic accidents. Therefore, it is critical to detect worker's fatigue for accident prevention. Method: After running exercises on a treadmill, participants were instructed to read a sentence and their voices were recorded under four different physical fatigue levels. Korean vowels of "아", "어", "오", "우", and "이" from the voice recorded were then used to collect formant 1 frequencies. Results: Results of separate ANOVAs showed a significant main effect of physical fatigue on formant 1 frequency of "아", "어", and "이". Furthermore, post-hoc comparisons revealed that formant 1 frequency of "아" was most sensitive to physical fatigue level employed in this experiment. Conclusion: Formant 1 frequencies of some vowels significantly decrease as the physical fatigue level increases. Application: Potential application of this study includes the development of a measure of physical fatigue state that is free from sensor attachment and requires little preparation.

• 음성과학
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• 제12권2호
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• pp.73-80
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• 2005

This study was analyzed to change of /i/ formant follow cochlear implantation periods for hearing impaired children with cochlear implantation. 20 hearing impaired children participated and acoustic analysis of /i/ was used CSL(Computerized Speech Lab; Model 4300b) annually. The data was captured the first formant, $2^{nd}$ & 3th formant frequency of /i/ and was analyzed using ANOVA. Multiple range test to investigate difference between group was treat with LSD and Duncan. The results of /i/ formant analysis for hearing impaired children with cochlear implantation, each formant at a year keeping with cochlear implantation was located at high frequency. In accordance with CI periods, the each formant decreased significantly, especially between a year and $2^{nd}$ year taking with cochlear implantation.

• 대한음성학회지:말소리
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• 제60호
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• pp.67-84
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• 2006

The purpose of this study is to find some acoustic parameters on frequency domain to distinguish the Korean nasals, $/m,\;n,\;{\eta}/$ from each other. The new parameters are devised on the basis of LTAS (Long Term Average Spectrum). The maximum peak amplitude and the relevant formant frequency are measured in low and high frequency range, respectively. The frequency of spectral valley and its energy level are also obtained in the specific frequency range of the spectrum. Spectral slope, total energy value in specific frequency range, statistical distribution of spectral energy like centroid, skewness, and kurtosis are suggested as new parameters as well. The parameters that show statistically significant differences across nasals are summerized as follows. 1) in syllable initial positions: the total energy value from 1,500 to 2,200 Hz(zeroENG); 2) in syllable final positions: the peak amplitude of the first formant(peak1_a), the formant frequency with maximum peak amplitude from 4,000 to 8,000 Hz(peak2_f), the maximum peak amplitude of the formant frequency from 4,000 to 8,000 Hz(peak2_a), and the total energy value from 1,500 to 2,200 Hz(zeroENG).

• 사상체질의학회지
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• 제16권1호
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• pp.61-73
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• 2004

This study was prepared to investigate the correlation between Sasang constitutional groups and voice characteristics using voice analysis system(in this study, CSL). I focused on the voice characteristics in terms of harmonics, Formant frequency and Formant Bandwidth. The subjects were 71 males. I classified them into three groups, that is Soeumin group, Soyangin group and Taeumin group. The classification method of Constitution used two ways, QSCCII(Questionnarie for the Sasang Constitution Classification II) and Interview with a specialist in Sasang Constitution. So 71 people were categorized into 31 Soeumin(people), 18 Soyangin(people) and 22 Taeumin(people). Pitch is approximately similar to the fundamental frequency(F0) in voices. Shimmer in dB gives an evaluation of the period-to-period variability of the peak-to-peak amplitude within the analyzed voice sample. FFT(Fast Fourier Transform) method in CSL can display sampled voices into harmonics. H1 is the first peak and h2 is the second peak in the harmonics. The amplitude difference of h1 and h2(h1-h2) can be explained as the speaker's phonation type, And Formant frequency and bandwidth can be explained as the speaker's vocal tract. So I checked the harmonics and Formant frequency and Bandwidth as the voice parameters. First I have captured /e/ voices from all subjects using microphone. And then I analyzed /e/ voices with CSL. Power Spectrum and Formant History is the menu in the CSL which can display harmonics and Formant frequency and bandwidth. The results about the correlation between Sasang Constitutional Groups and voice parameters are as follows; 1. There is no significant amplitude difference of harmonics(h1-h2) among three groups. 2. There is the significant difference between Soeumin Group and Soyangin Group in Formant Frequency 1 and Formant Bandwidth 1(p<0.05). Any other parameters have no significance. I assume that Soyangin Group has clearer and brighter voice than Soeumin Group according to the Formant Bandwidth difference. And I think its result has coincidence with the context of "Dongyi Suse Bowon" and "Sasangimhejinam".

• 대한후두음성언어의학회지
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• 제15권2호
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• pp.98-111
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• 2004

Background and Objectives : The purpose of this study is to analyze the difference of Fundamental Frequency(Hz), Closed Quotient(Qx ; %), Intensity(dB), Vocal tract length and width(cm), formant frequency(Hz), level of formant frequency(dB) depending on the larynx position. Materials and Methods : One professional male singer(career : 28 years) produced sustained vowel /a/,/e/,/i/,/o/,/u/ in two larynx position (higher, lower) with Dr. Speech and video fluoroscopy was used to quantify the vocal tract morphology. Results : In lower larynx position, CQ is increased 9.8% and Intensity is increased about 10% and level of Formant Frequency is increased. And also Vocal tract length is longer 2.4cm, Vocal tract width(Anterior width : 0.4cm, lateral width : 0.2cm) is wider than in higher larynx position. Conclusions : Singer's formant has a prominent spectrum envelope peak near 2400-2600Hz by clustering of F3, F4 and F5 near 3400Hz in lower larynx position.