Automatic style classification of jazz records with respect to rhythm, tempo, and tonality

In this paper, we focus on the automatic classification of jazz records. We propose a novel approach where we break down the ambiguous task, which is commonly referred to as genre classification, into three more specific semantic levels. First, the rhythm feel (swing, latin, funk, two-beat) characterizes the basic groove organization and most often relates to the rhythm section. Second, the tonality type (functional, blues, bebop harmony) describes the general harmonic organization of the underlying composition, which serves the soloist as a guideline for the improvisation. Third, the tempo class (slow, medium, up) provides a rather broad categorization of the overall tempo of a song. We consider three individual classification tasks with respect to the different descriptors. A set of 229 jazz recordings was selected and labeled by musicology and jazz students as part of the Jazzomat Research Project. For the three tasks, we conduct several classification experiments in order to investigate the usefulness of certain features and feature groups in general as well as pre-processing methods such as feature selection and feature space transformation. For a baseline classification experiment, we use low-level audio features which are widely used in Music Information Retrieval (MIR) research. As second step, we test several recently proposed mid-level features for modeling rhythmic or harmonic content of audio data. We systematically evaluate different modifications and combinations of these features. By testing decision trees as classifiers, the obtained decision rules provide an opportunity for a musicological interpretation of the classification process. Beyond that, we also investigate which features were selected for the different tasks by an automatic feature selection algorithm. The results of this interdisciplinary study have potential implications for jazz research as well as for content-based audio analysis tasks such as music similarity search and music recommendation in general

In-Ear Headphone System with Piezoelectric MEMs Driver

This article presents a prototype in-ear headphone system based on a previously disclosed piezoelectric MEMS driver technology (piezoMEMS). The centerpiece of the earphone is a 4 mm x 4 mm piezoMEMS chip loudspeaker that on its own achieves broadband sound pressure levels of up to 110 dB in an IEC 60318-4 ear simulator. A specifically designed enclosure allows for easy installation of the piezoMEMS driver and takes first steps in optimizing the acoustic performance. Furthermore, the system comprises a specially tailored amplifier as well as a dedicated signal processing concept. The article describes the ideas behind the system, discusses the particular challenges in designing the piezoMEMS earphone, shows measurement results, and, finally, discusses the vast opportunities for future research

Design and Electroacoustic Analysis of a Piezoelectric MEMS In-Ear Headphone

This article takes an in-depth look at an in-ear headphone demonstrator with a piezoelectric MEMS driver. The MEMS transducer and the demonstrator system including earphone enclosure, signal processing, and application-specific amplifier are described. The main focus of this study lies on an exhaustive electroacoustic analysis of a MEMS earphone, comprising an electrical impedance measurement, various acoustical measurements, and an investigation of the thermal behavior of piezoelectric MEMS drivers. The results show the high potential of this technology for in-ear applications and promise even greater acoustic performance with future improvements

Zwei-Wege-Lautsprecher basierend auf MEMS-Technologie

Dieser Beitrag stellt einen neuartigen Zwei-Wege-Miniaturlautsprecher vor, der für die breitbandige Klangwiedergabe insbesondere in Ohrnähe geeignet ist. Der Lautsprecher nutzt einen 10 mm x 10 mm großen Woofer und einen 6 mm x 6 mm großen Tweeter, die beide in MEMS-Technologie gefertigt und gemeinsam auf einer Leiterplatte montiert werden. Die zwei MEMS-Schallwandler bestehen jeweils aus vier unabhängigen dreieckigen Biegeaktoren, die gleichzeitig die aktive Strahlerfläche – sprich Membran – bilden. Die vier Aktoren sind durch kleinstmögliche Spalte voneinander strukturell entkoppelt. Mit der gewählten Spaltbreite bilden sie eine akustisch geschlossene Membranfläche, sodass im relevanten Frequenzbereich keine Ausgleichsströmungen zwischen Vorder- und Rückseite durch die Spalte stattfinden. Ein auf der Leiterplatte angebrachtes flaches Gehäuse mit kleinem Volumen verhindert den klassischen akustischen Kurzschluss. Darüber hinaus wird der Zwei-Wege-Miniaturlautsprecher mit einer digitalen Signalverarbeitung für die aktive Frequenzweiche und zur Entzerrung des Frequenzgangs kombiniert. Das Gesamtsystem wurde unter Freifeldbedingungen in einem reflexionsarmen Raum einer umfassenden akustischen Charakterisierung unterzogen. Die erzielten akustischen Eigenschaften zeigen, dass die MEMS-Technologie eine attraktive Basis für den Lautsprecher der Zukunft darstellt. Systeme wie der hier vorgestellte MEMS-Lautsprecher können unter anderem in Mobilgeräten wie Smartphones und Tablets Anwendung finden