Erdem Ünal

A Hierarchical Approach to Makam Classification of Turkish Makam Music, Using Symbolic Data

Abstract A method for hierarchical classification of makams from symbolic data is presented. A makam generally implies a miscellany of rules for melodic composition using a given scale. Therefore, makam detection is to some level similar to the key detection problem. The proposed algorithm classifies makams by applying music theoretical knowledge and statistical evidence in a hierarchical manner. The makams using similar scales are first grouped together, and then identified in detail later. The first level of the hierarchical decision is based on statistical information provided by the n-gram likelihood of the symbolic sequences. A cross-entropy based metric, perplexity, is used to calculate similarity between makam models and the input music piece. Later, using statistical features related to the content of the piece, such as the tonic note, the average pitch level for local excerpts and the overall pitch progression, a more detailed identification of the makam is achieved. Different length n-grams and representation paradigms are used, including the Arel theory, the 12 tone equal tempered representation, and interval contour. Results show that the hierarchical approach is better, compared to a straightforward n-gram classification, for the makams which have similar pitch space, such as Hüseyni–Muhayyerand Rast–Mahur. Using the proposed methodology, the system’s recall rate increases from 88.7% to 90.9% where there exists still some confusion between the makams Uşşak and Beyati.

An acoustic based sniper detection system prototype

In this work, an acoustic-based sniper detection system prototype geometry and its operational principals are presented from the signal processing perspective. The prototype consists of a microphone network positioned in a specific geometric structure in the three dimensional space. The system depends on estimating the delay of arrival of sound waves reaching the microphones and using the delay information in order to calculate the direction of the sound source. The time difference of arrival problem is solved by using the generalized cross correlation approach. The estimated delay is then transformed into angles using the far field approximation. The found angle is the angle between the sound source and the microphone pair axis. Using the angles calculated for different microphone pairs, the direction is reported with azimuth and elevation. The study reports the simulation results and laboratory experiments.

Tracking music from media using reduced pitch class profile features

In this paper, a system that robustly searches and matches a music input signal to a music collection database using a hash table that is constructed from n-grams of reduced tonal profile. Since the problem that is being studied requires high performance, efficiency and scalability, not only the retrieval accuracy should be high, but also the systems workload on the processing unit and the memory should be in acceptable ranges. With respect to other conventional features, the tonal profile features extracted in this work requires much less space. From the tonal features n-gram blocks are constructed and used in a look up table. Whenever the input signal satisfies some constraints, matching and retrieval are performed The results show that the computation performance and the retrieval accuracy is at promising levels.

An acoustic surveillance system for critical event detection

In this paper, a novel acoustic surveillance system, that can be used in critical facilities and infrastructures, border security and public premises is introduced. As an application, an acoustic surveillance system that detects gunshots from recorded acoustic signals, and identifies the originating weapon type is selected. Mel Frequency Cepstral Coefficients, zero crossing rate, spectral percentile, spectral centroid, spectral spread and spectral flatness are used as features in different classifiers, namely, the Gaussian Mixture Models, k-Nearest Neighbor and Support Vector Machines, and their classification performances are compared. The feature space that is composed of features from four different classes is visually analyzed by using the Principle Component Analysis. For gun type identification, the best classification performance of 80% was achieved using the k-NN classifier.

Distance calculation using omnidirectional microphones in shot estimation systems

In this document, our latest work on distance estimation algorithm of acoustic based shot estimation system will be discussed. Information about our 4 point sensor array and the omni-directional microphones will be provided. Using Gaussian Mixture Models, a voice activity detection front end is designed. When a shot is detected, critical raw data is processed for directional measurement using generalized cross correlation based time difference of arrival. Applying directional calculation for both the muzzle blast and the shockwave, shot distance is estimated. Under the assumption that the bullet has speed and ideal environmental conditions, according to MATLAB simulations, depending on the miss distance, on average 5,6% distance calculation error is detected for distances up to 1000 meters. For limited amount of real audio data, the usability of this approach is discussed for 300m shot distance and a 10m miss distance.

Automatic melodic segmentation of Turkish makam music scores

Automatic melodic segmentation is one of the important steps in computational analysis of melodic content from symbolic data. This widely studied research problem has been very rarely considered for Turkish makam music. In this paper we first present test results for state-of-the-art techniques from literature on Turkish makam music data. Then, we present a statistical classification-based segmentation system that exploits the link between makam melodies and usual and makam scale hierarchies together with the well-known features in literature. We show through tests on a large dataset that the proposed system has a higher accuracy.

TÜBİTAK-BİLGEM Shot Estimation System (SES)

In this work, design and experimental studies related to TUBITAK-BILGEM Shot Estimation System (AKS in Turkish) will be discussed. AKS is composed of three parts which are, a microphone array that has a specific structural design, an electronic unit that enables synchronous recording of the microphone signals and a graphical user interface that prompts the output of the system. Basic goal is to detect the position of a pre-defined sound source in terms of cartesian coordinates with respect to the original position of the system. First, the position of the sound source is detected in the cartesian coordinates by using only the time difference of arrival information. The time difference of arrival problem is solved using the generalized cross correlation function. In order to compensate for the false alarms that is very common in these systems, an energy based and a Mel Frequency Cepstrum Coefficients based two stage classifier is used. System is tested with shots from four different hand held rifles, from two different distances for each 10 degree angles spreading over 180 degrees. The average directional error for 100m shots is 2,69 degrees while the error declines to 1,51 degrees for 200m shots. The precision of the system is %84,6 while the recall is %96,2.

Musıc tracking system for royalty rıghts management: Geometrıcal representation of musıc

Representation of music with the purpose of matching queries is one of the popular sub fields of information retrieval. In this paper, studies for to the project named ‘Music Tracking System for Royalty Rights Management’ funded by the TÜBıTAK ARDEB 3501 grant program is presented. Related to technical representation of music for music matching, the tonal music space theory and its background is explained. The short time spectral analysis features are mapped on to the three dimensional musical space for meaningful representation. The symbolic representation is then integrated into a look-up table with N-gram blocks. This process is held for each database entry. The look up table becomes an N-gram block representation of the entire database. When a match query is available, the symbolic sequence of the query is searched in the look-up table and a match result is presented to the user. In a database of ten thousand music samples, full clip and partial clip query matching results and technical details about the performance of the system is shown.