Fundamental frequency

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

Pitch related to spectral edges of broadband signals.

Abstract: A complex tone often evokes a pitch sensation associated with its extreme spectral components, besides the holistic pitch associated with its fundamental frequency. We studied the edge pitch created at the upper spectral edge of complexes with a low-pass spectrum by asking subjects to adjust the frequency of a sinusoidal comparison tone to the perceived pitch. Measurements were performed for different values of the fundamental frequency and of the upper frequency of the complex as well as for three different phase relations of the harmonic components. For a wide range of these parameters the subjects could adjust the comparison tone with a high accuracy, measured as the standard deviation of repeated adjustments, to a frequency close to the nominal edge frequency. The detailed dependence of the matching accuracy on temporal parameters of the harmonic complexes suggests that the perception of the edge pitch in harmonic signals is related to the temporal resolution of the hearing system. This resolution depends primarily on the time constants of basilar-membrane filters and on additional limitations due to neuronal processes.

Second-Order Harmonic Reduction Technique for Photovoltaic Power Conditioning Systems Using a Proportional-Resonant Controller

Abstract: This paper proposes a second-order harmonic reduction technique using a proportional-resonant (PR) controller for a photovoltaic (PV) power conditioning system (PCS). In a grid-connected single-phase system, inverters create a second-order harmonic at twice the fundamental frequency. A ripple component unsettles the operating points of the PV array and deteriorates the operation of the maximum power point tracking (MPPT) technique. The second-order harmonic component in PV PCS is analyzed using an equivalent circuit of the DC/DC converter and the DC/AC inverter. A new feed-forward compensation technique using a PR controller for ripple reduction is proposed. The proposed algorithm is advantageous in that additional devices are not required and complex calculations are unnecessary. Therefore, this method is cost-effective and simple to implement. The proposed feed-forward compensation technique is verified by simulation and experimental results.

Sine-Wave Amplitude Coding at Low Data Rates

Abstract: An analysis/synthesis system based on the sinusoidal speech model has been developed [1] In that system, the sine-wave amplitudes and frequencies are located by searching for the peaks of the magnitude of the short-time Fourier transform (STFT) of the input speech The phases are computed from the real and imaginary parts of the STFT at the measured frequencies The frequencies on successive frames are matched, used in a cubic phase interpolator and applied to a sine-wave generator Each sine wave is amplitude-modulated by the linear interpolation of the matched sine-wave amplitudes At a 10 ms frame rate, this system produces speech that is perceptually indistinguishable from the original [1] Since it is not possible to code all of the sine-wave parameters at low data rates, a system has been developed that codes the sine-wave frequencies by fitting a harmonic set of sine waves to the input waveform using a modified mean-squared error criterion [2], and codes the phase information implicitly using a voicing adaptive transition frequency to provide for a mixed voiced/unvoiced phase excitation model [3] Provided a postfilter is used at the synthesizer to attenuate the noise in the formant nulls, the speech synthesized by this system is of quite high quality having achieved a DAM score of 630 in the uncoded mode Since the fundamental frequency can be coded using ≈ 7 bits and the voicing measure can be coded using ≈ 3 bits, then the possibility exists for good speech quality at low data rates provided the sine-wave amplitudes can be coded efficiently In this paper the zero-phase, harmonic analysis/synthesis system and the post-filter design methodology will be described and then the various techniques that have been examined for coding the sine-wave amplitudes will be discussed