Tissue engineering scaffolds employed for bone tissue regeneration are multiphase architectured media, which usually consist of periodic arrays of soft inclusions (tissue, fluid, voids, or some combination thereof) embedded in a hard scaffold matrix. The primary process at play during their insertion is the scaffold resorption, together with the gradual bone in-growth within the pores, which occurs at a length scale of a few hundred micrometers. Their effective mechanical behavior at the tissue scale results from the combination of two main factors [1], namely (i) the properties of the constituent phases (soft or hard) and their respective volume fractions; and (ii) the presence of a structural organization (periodic microstructure), not to mention that both factors are time dependent (at the biological time scale). As bulk phononic crystal analogs, scaffolds should therefore support elastic wave propagation in the megahertz (MHz) regime, whose frequency-dependent nature is expected to arise from a combination of internal resonances of the unit cells and wave interferences (Bragg scattering), which take place at frequencies where the effective wavelength is commensurate to twice the periodicity constant [2]. In this context, the rational design of multiphase architectured scaffolds that display an acoustic signature reflecting their microstructure could open the way towards the development of ultrasound characterization methods for the monitoring of their integration to the surrounding biological environment. To this end, it is necessary both to have a precise knowledge of the acoustic properties of the constituent materials and to accurately model the impact of the microstructure. In this work, we discuss the capability of a multi-material 3D printing technology to design bio-mimicking micro-architectured media with programmable ultrasonic responses, with the aim of replicating such multiphase scaffolds formed by sub-millimeter unit cells in a controlled laboratory environment. First, the viscoelastic properties of the constituent phases are identified by characterizing homogeneous samples in the MHz regime, which exhibit dispersive losses that are described using a frequency power law model [3]. These properties are then used to feed models of the propagation of longitudinal ultrasound waves through time-evolving multiphase architectured media [4]. In particular, transmission and reflection spectra are computed for the viscoelastic, finite-size medium using a finite element method in the frequency domain. This approach allows disentangling the relative contributions of viscoelasticity and periodicity on ultrasound signatures such as dispersion, attenuation, and bandgaps localization. Finally, the modeling outcomes are confronted with experiments conducted on 3D-printed samples, which exhibit a 2D periodicity at a length scale of a few hundreds of micrometers. Altogether, the obtained results shed light on the modeling characteristics to be considered when predicting the complex acoustic behavior of architectured media in the ultrasonic regime.