Sinusoidal models have long been used in the processing of audio signals. Many of these models are usually used to select significant frequencies in the amplitude spectrum for analysis and synthesis purposes. Therefore, when using these models, it is important to estimate the true frequency of the multiple sinusoids present in the signal. In this paper, the performance of frequency estimation using the phase vocoder is investigated. The performance of the frequency estimation under varying noise power and different window shapes and sizes is analyzed. The effect of the presence of multiple sinusoids in the signal on the frequency estimation is also discussed. In particular, the frequency bias resulting from the presence of multiple sinusoids, the selection of optimum window size and the impact of the frequency of the sinusoids on the estimates are comprehensively investigated

Sigma-delta (/spl Sigma/-/spl Delta/) modulators have been widely used over the last few decades, and one of their many applications has been in the field of FIR filter design. In this paper, we investigate the performance of multiplier free FIR filter design using the Look Ahead Decision Feedback (LADF) /spl Sigma/-/spl Delta/ architecture. The LADF /spl Sigma/-/spl Delta/ architecture, which has not been used in FIR filter design before, is compared with other conventional /spl Sigma/-/spl Delta/ architectures. It is shown that the LADF architecture has relatively low noise power at low frequencies and is preferable over the other modulators in the design of multiplier free FIR filters. The selection of demodulator filters for reducing quantization noise due to the LADF /spl Sigma/-/spl Delta/ architecture is also addressed in the paper. Using low-pass FIR filter design examples, the appropriate filter design methodology is presented in the paper.