This correspondence deals with multiwavelets, which are a recent generalization of wavelets in the context of time-varying filter banks and with their applications to signal processing and especially compression. By their inherent structure, multiwavelets are fit for processing multichannel signals. This is the main issue in which we will be interested here. The outline of the correspondence is as follows. First, we will review material on multiwavelets and their links with multifilter banks and, especially, time-varying filter banks. Then, we will have a close look at the problems encountered when using multiwavelets in applications, and we will propose new solutions for the design of multiwavelets filter banks by introducing the so-called balanced multiwavelets.Index Terms-Balancing, multifilter, multiwavelet, prefiltering, timevarying filter bank.1053-587X/98$10.00 © 1998 IEEE L = N 0 1 and obtain that h(t) is also causal and starts at t = 0, i.e., we have h(t) = (01) t g 3 (2N 0 1 0 t).

Abstract-This paper deals with multiwavelets and the different properties of approximation and smoothness associated with them. In particular, we focus on the important issue of the preservation of discrete-time polynomial signals by multifilterbanks. We introduce and detail the property of balancing for higher degree discrete-time polynomial signals and link it to a very natural factorization of the refinement mask of the lowpass synthesis multifilter. This factorization turns out to be the counterpart for multiwavelets of the well-known zeros at condition in the usual (scalar) wavelet framework. The property of balancing also proves to be central to the different issues of the preservation of smooth signals by multifilterbanks, the approximation power of finitely generated multiresolution analyses, and the smoothness of the multiscaling functions and multiwavelets. Using these new results, we describe the construction of a family of orthogonal multiwavelets with symmetries and compact support that is indexed by increasing order of balancing. In addition, we also detail, for any given balancing order, the orthogonal multiwavelets with minimum-length multifilters.

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Highlights (3 to 5 bullet points, maximum 85 characters, including spaces, per bullet point, to be submitted in a separate editable file in the online submission system, using 'Highlights' in the file name). • Marine noise is a widespread source of pollution in the Mediterranean Sea • Noise pollution produces a multitude of impacts on marine fish and invertebrates • Marine noise pollution impacts individuals to ecosystems • A variety of measures could be adopted to mitigate marine noise pollution Abstract (max 150 words): Marine noise pollution (MNP) can cause a multitude of impacts on many organisms, but information is often scattered and general outcomes difficult to assess. We systematically reviewed the available knowledgeliterature about MNP impacts on Mediterranean fish and invertebrates. Both chronic and acute MNP produced by several human activities-e.g. maritime traffic, pile driving, air guns-were found to cause detectable effects on intraspecific communication, vital processes, physiology, behavioral patterns, health status and survival. These individual-based effects can extend to induce population-and ecosystem-wide alterations, especially when MNP impacts functionally important species, such as keystone predators and habitat forming species. Curbing the threats of MNP in the Mediterranean Sea is not an easya challenging task, but a variety of measures should could be adopted to mitigate MNP impacts. Successful measures will require more precise accurate information on impacts, and that effective management of MNP actually becomes a priority in the policy makers' agenda.