Fundamental frequency

About: Fundamental frequency is a research topic. Over the lifetime, 8941 publications have been published within this topic receiving 131583 citations.

A Comparison of High Precision FO Extraction Algorithms for Sustained Vowels

Abstract: Perturbation analysis of sustained vowel waveforms is used routinely in the clinical evaluation of pathological voices and in monitoring patient progress during treatment. Accurate estimation of voice fundamental frequency (F0) is essential for accurate perturbation analysis. Several algorithms have been proposed for fundamental frequency extraction. To be appropriate for clinical use, a key consideration is that an F0 extraction algorithm be robust to such extraneous factors as the presence of noise and modulations in voice frequency and amplitude that are commonly associated with the voice pathologies under study. This work examines the performance of seven F0 algorithms, based on the average magnitude difference function (AMDF), the input autocorrelation function (AC), the autocorrelation function of the center-clipped signal (ACC), the autocorrelation function of the inverse filtered signal (IFAC), the signal cepstrum (CEP), the Harmonic Product Spectrum (HPS) of the signal, and the waveform matching function (WM) respectively. These algorithms were evaluated using sustained vowel samples collected from normal and pathological subjects. The effect of background noise and of frequency and amplitude modulations on these algorithms was also investigated, using synthetic vowel waveforms.

Electronic ballast for operating lamps in parallel

Abstract: An electronic ballast for powering at least two rapid start, parallel connected fluorescent lamps. Associated with each lamp is a serially connected choke and capacitor combination. A train of pulses of alternating polarity having a fundamental frequency, which is generated by an inverter, is applied to each serially connected combination. Each combination is characterized by a resonant frequency which is other than an odd harmonic of and at least two times and preferably √ 5 times greater than the fundamental frequency. Reduction in filament heating, following lamp ignition, is provided through the addition of voltages applied to each filament which are substantially out of phase with each other.

Second‐Harmonic Generation in an Elastic Surface Wave in α‐Quartz

Abstract: Second‐harmonic generation was observed in an elastic surface wave propagating in the y direction on the x surface of α‐quartz The waves were generated and detected by means of interdigital electrode transducers The fundamental frequency was 9 MHz The amplitude of the second‐harmonic signal increased linearly with distance along the crystal surface A nearly perfect square‐law dependence of second‐harmonic power on fundamental power was found The ratio of second‐harmonic to fundamental power was −438 dB at a distance of 22 cm and a fundamental input power of 1 W The results are in quantitative agreement with theory

Pitch-synchronous time-scaling for prosodic and voice quality transformations.

Abstract: Current time-domain pitch modification techniques have well known limitations for large variations of the original fundamental frequency This paper proposes a technique for changing the pitch and duration of a speech signal based on time-scaling the linear prediction (LP) residual The resulting speech signal achieves better quality than the traditional LP-PSOLA method for large fundamental frequency modifications By using nonuniform time-scaling, this technique can also change the shape of the LP residual for each pitch period This way we can simulate changes of the most relevant glottal source parameters like the open quotient, the spectral tilt and the asymmetry coefficient Careful adjustments of these source parameters allows the transformation of the original speech signal so that it is perceived as if it was uttered with a different voice quality or emotion