A pitch tracking algorithm is described which operates in the time domain from a conditioned linear prediction residual and applies dynamic programming to optimally determine both pitch and voicing.

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A new and general wave theoretical wavelet estimation method is derived. Knowing the seismic wavelet is important both for processing seismic data and for modeling the seismic response. To obtain the wavelet, both statistical (e.g., Wiener‐Levinson) and deterministic (matching surface seismic to well‐log data) methods are generally used. In the marine case, a far‐field signature is often obtained with a deep‐towed hydrophone. The statistical methods do not allow obtaining the phase of the wavelet, whereas the deterministic method obviously requires data from a well. The deep‐towed hydrophone requires that the water be deep enough for the hydrophone to be in the far field and in addition that the reflections from the water bottom and structure do not corrupt the measured wavelet. None of the methods address the source array pattern, which is important for amplitude‐versus‐offset (AVO) studies. This paper presents a method of calculating the total wavelet, including the phase and source‐array pattern. When the source locations are specified, the method predicts the source spectrum. When the source is completely unknown (discrete and/or continuously distributed) the method predicts the wavefield due to this source. The method is in principle exact and yet no information about the properties of the earth is required. In addition, the theory allows either an acoustic wavelet (marine) or an elastic wavelet (land), so the wavelet is consistent with the earth model to be used in processing the data. To accomplish this, the method requires a new data collection procedure. It requires that the field and its normal derivative be measured on a surface. The procedure allows the multidimensional earth properties to be arbitrary and acts like a filter to eliminate the scattered energy from the wavelet calculation. The elastic wavelet estimation theory applied in this method may allow a true land wavelet to be obtained. Along with the derivation of the procedure, we present analytic and synthetic examples.

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We present a general wave theoretical method for extracting the normal component of the particle velocity from marine pressure data. A possible use of the normal component of the particle velocity and the pressure is the separation of upgoing and downgoing waves at the receivers. For one special acquisition geometry, the source wavelet can also be estimated. The method in principle is exact. No information about the properties of the elastic earth is required. When the pressure data are recorded on a single surface, it is necessary to know the source signatures if the source array location is above the receiver surface. If the sources are located below, the signatures need not be known. The locations of the individual receivers must be specified, and the reflecting properties of the sea surface must be known. When the receiver surface is plane and horizontal, the extraction process can be performed in the frequency‐horizontal wavenumber domain. The normal component of the particle velocity can furthermore be extracted from pressure data recorded at two surfaces at different depths. In this case the reflectivity of the sea surface does not come into play; it is only the medium properties between the two receiver surfaces that enter the problem. The actual depths of the receivers need not be known, only their relative distances. If the sources are located above the uppermost receiver surface, the source signatures can also be estimated. A simple synthetic data example demonstrates the extraction of the normal component of the pressure from the pressure field recorded along a dipping receiver line below a free surface.