Sound power and timbre as cues for the dynamic strength of orchestral instruments.

In a series of measurements, the sound power of 40 musical instruments, including all standard modern orchestral instruments, as well as some of their historic precursors from the classical and the baroque epoch, was determined using the enveloping surface method with a 32-channel spherical microphone array according to ISO 3745. Single notes were recorded at the extremes of the dynamic range (pp and ff) over the entire pitch range. In a subsequent audio content analysis, audio features were determined for all 3482 single notes using the timbre toolbox. In order to analyze the relative contributions of timbre- and amplitude-related properties to the expression of musical dynamics in different instruments, Bayesian linear discriminant analysis and generalized linear mixed modelling were employed to determine those audio features discriminating best between extremes of dynamics both within and across instruments. The results from these measurements and statistical analyses thus deliver a comprehensive picture of the acoustical manifestation of "musical dynamics" with respect to sound power and timbre for all standard orchestral instruments.

Generation and analysis of an acoustic radiation pattern database for forty-one musical instruments.

A database of acoustic radiation patterns was recorded, modeled, and analyzed for 41 modern or authentic orchestral musical instruments. The generation of this database included recordings of each instrument over the entire chromatic tone range in an anechoic chamber using a surrounding spherical microphone array. Acoustic source centering was applied in order to align the acoustic center of the sound source to the physical center of the microphone array. The acoustic radiation pattern is generated in the spherical harmonics domain at each harmonic partial of each played tone. An analysis of the acoustic radiation pattern complexity has been performed in terms of the number of excitation points using the centering algorithm. The database can be used both for studying the radiation of musical instruments itself, as well as for the implementation of radiation patterns in room acoustical simulations and auralization in order to obtain a spatial excitation of the room closer to reality.

Generation of a reference radiation pattern of string instruments using automatic excitation and acoustic centering.

Radiation patterns of musical instruments are important for the understanding of music perception in concert halls, and may be used to improve the plausibility of virtual acoustic systems. Many attempts have been performed to measure the spatial response of musical instruments using surrounding spherical microphone arrays with a limited number of microphones. This work presents a high-resolution spatial sampling of the radiation pattern of an electrically excited violin, and addresses technical problems that arise due to mechanical reasons of the excitation apparatus using acoustic centering.