Valimaki, V. 1995 (Dec.). Discrete-Time Modeling of Acoustic Tubes Using Fractional Delay Filters. Ph.D. thesis, Report no. 37, Helsinki University of Technology, Faculty of Electrical Engineering, Laboratory of Acoustic and Audio Signal Processing, Espoo, Finland.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....one delay to another (as in a hammer on or pull o simulation in a string model) gives rise to a transient artifact due to the recursive nature of the allpass lter. Recently, Vesa V alim aki has developed a general transient elimination scheme for recursive digital lters of arbitrary order [V alim aki et al. 1995]. Another popular choice is Lagrange interpolation [Karjalainen et al. 1991] which is a special case of FIR lter interpolation; while the switching problem does not arise since the interpolating lter is nonrecursive, there is still a time varying amplitude distortion at high frequencies. In ....

....at DC (zero frequency) while the gain generally rolls o at high frequencies. Allpass interpolation can be seen as trading o this frequency dependent amplitude distortion for additional frequency dependent delay distortion [Cook 1995] A comprehensive review of Lagrange interpolation appears in [V alim aki 1995] Both allpass and FIR interpolation su er from some delay distortion at high frequencies due to having a nonlinear phase response at non integer desired delays. This distortion is normally inaudible, even in the rst order case, causing mistuning or phase modulation only in the highest partial ....

Valimaki, V. 1995 (Dec.). Discrete-Time Modeling of Acoustic Tubes Using Fractional Delay Filters. Ph.D. thesis, Report no. 37, Helsinki University of Technology, Faculty of Electrical Engineering, Laboratory of Acoustic and Audio Signal Processing, Espoo, Finland.

....a multi channel reverberator [91, 92, 93] 4. 1 Digital Waveguide The main contributor to the theory of digital waveguides has been Smith [94, 5, 95] The method was first applied to artificial reverberation [96] although nowadays the main application is simulation of one dimensional resonators [5, 97, 3, 6, 7]. A digital waveguide is a bidirectional digital delay line as illustrated in Fig. 4.1. The state of the system is obtained by summing the two wave components traveling to opposite directions y#x; t##y # #x; t##y # #x; t#: 4.1) It can be shown that the digital waveguide is an exact solution ....

.... (a) the original mesh with 4 directions, b) the hypothetical version with H propagation directions, c) the case H # # for which the best results have been obtained, and (d) the new interpolated waveguide mesh, in which the new nodes are spread onto the neighboring nodes by deinterpolation [101, 97, 100][P5,P10] Interpolated Rectangular Mesh Structure In the 2 D rectangular digital waveguide mesh algorithm, each node has four neighbors, two on both axes (points labelled p # in Fig. 4.7(a) These are connected by unit delay elements. The author has extended this scheme to an arbitrary number ....

V. V alim aki. Discrete-Time Modeling of Acoustic Tubes Using Fractional Delay Filters. Doctoral thesis, Helsinki University of Technology, Lab. of Acoustics and Audio Signal Processing, Report 37, 1995. Available at http://www.acoustics.hut.fi/#vpv/publications/vesa phd.html.

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