Fundamental frequency

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

A scheme for pitch extraction of speech using autocorrelation function with frame length proportional to the time lag

Abstract: Although pitch extraction schemes based on the short-time autocorrelation function offer reliable results for most of the speech signal, the autocorrelation peaks indicating fundamental period fluctuate with frame position, causing occasional pitch extraction errors. In order to reduce these errors, a scheme using a new definition of normalized short-time autocorrelation function is proposed. One of the major advantages of the definition over conventional ones is that the frame length changes in proportion to the time lag, and, therefore, the input speech can be analyzed without any knowledge of the fundamental frequency range of the speaker. Two methods are proposed for the normalization, and the one compensating for variations of the short-time power of the waveform is shown to offer better results. A system for pitch extraction is constructed on a workstation, and the validity of the proposed scheme is demonstrated by experiments using the connected speech of male and female announcers. >

Parasitic-free measurement of the fundamental frequency response of a semiconductor laser by active-layer photomixing

Abstract: We report the measurement of the fundamental (intrinsic) frequency response of a GaAs semiconductor laser to 12 GHz by directly photomixing two optical sources in the active region of the laser. This novel technique reveals the underlying fundamental frequency response of the device as parasitic effects are avoided. Well beyond the relaxation resonance, the theoretically predicted 40 dB/dec signal rolloff is observed. Other features of the measured response function are also observed to be the theoretical ideal.

Conditional mean and maximum likelihood approaches to multiharmonic frequency estimation

Abstract: The performance of an extended Kalman filter (EKF) applied to the problem of estimating the (assumed constant) parameters (fundamental frequency, harmonic phases, and amplitudes) of a complex multiharmonic signal measured in noise is shown to be asymptotically (i.e., as the number of measurements tends to infinity) efficient. The Cramer-Rao (CR) bounds associated with the estimation problem are derived for the case where the measurements commence at an arbitrary time distinct from zero. >

Frequency domain fluorometry using coherent sampling

Abstract: Apparatus and methods for measuring response of a chemical composition to light, as by frequency domain, phase angle, or modulation fluorometry and/or phosphorimetry. Pulsed light having a known fundamental frequency is applied to the composition thereby eliciting response light varying at the fundamental frequency and at harmonics thereof. The response light signal may be sampled according to a wave-skipping sampling scheme, and the sampled response signal may be transformed into a frequency domain representation, as by a digital fast Fourier transform technique. A reference signal derived from the excitation light may be similarly processed and the results used as a basis for comparison to derive properties of the chemical composition such as phase and modulation response of the composition to the fundamental and harmonic frequencies. The invention provides rapid monitoring and determination of luminescence characteristics. Multiple excitation frequencies may be applied simultaneously and the resulting response signals may be separated and separately sampled.