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Aki Härmä

Philips Research Laboratories, Eindhoven, The Netherlands.
with my name at philips.com
I am from Finland. I finished my PhD work in the laboratory of Acoustics and Audio Signal Processing at Helsinki University of Technology (HUT) in 2001. In 2000-2001 I worked as a post-doc at Lucent Bell Laboratories and later Agere Systems (Murray Hill, NJ, USA). After an extended post-doc period at HUT I joined the Digital Signal Processing group at Philips Research, Eindhoven, The Netherlands, in 2004.

Journal articles

2011
Eleftheria Georganti, Tobias May, Steven van de Par, Aki Härmä, John Mourjopoulos (2011)  Speaker Distance Detection using a Single Microphone   IEEE Trans. Audio, Speech and Language Processing  
Abstract: A method to detect the distance of a speaker from a single microphone in a room environment is proposed. Several features, related to statistical parameters of speech source excitation signals, are introduced and are shown to depend on the distance between source and receiver. Those features are used to train a pattern recognizer for distance detection. The method is tested using a database of speech recordings in four rooms with different acoustical properties. Performance is shown to be independent of the signal gain and level, but depends on the reverberation time and the characteristics of the room. Overall, the system performs well especially for close distances and for rooms with low reverberation time and it appears to be robust to small distance mismatches. Finally, a listening test is conducted in order to compare the results of the proposed method to the performance of human listeners.
Notes: Accepted for publication
2006
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Book chapters

2009
1998
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1996

Conference papers

2013
2012
2011
Aki Härmä (2011)  Estimation of the Energy Ratio Between Primary and Ambience Components in Stereo Audio Data   In: Proc. 19th European Signal Processing Conf. (EUSIPCO 2011) Barcelona, Spain:  
Abstract: Stereo audio signal is often modeled as a mixture of instantaneously mixed primary components and uncorrelated ambience components. This paper focuses on the estimation of the primary-to-ambience energy ratio, PAR. This measure is useful for signal decomposition in stereo and multichannel audio coding, format conversion, and spatial audio enhancement. The conventional approaches for the estimation of the ratio are based on the ratio of eigenvalues which requires equal energies of the ambience signals. This often leads to an inaccurate estimate of PAR. An alternative measure is proposed which reduces those estimation errors but requires a priori information about the primary component signal. The performance of the method is demonstrated with synthetic signals and a large collection of stereo audio data.
Notes:
Georgina Tryfou, Aki Härmä, Athanasios Mouchtaris (2011)  TEMPO ESTIMATION BASED ON LINEAR PREDICTION AND PERCEPTUAL MODELLING   In: 12th International Society for Music Information Retrieval Conference (ISMIR 2011) Miami, FL, USA:  
Abstract: Many applications demand the automatic induction of the tempo of a musical excerpt. The tempo estimation systems follow a general scheme that consists of two main steps: the creation of a feature list and the detection of periodicities on this list. In this study, we propose a new method for the implementation of the ï¬rst step, along with the addition of a ï¬nal step that will enhance the tempo estimation procedure. The proposed method for the extraction of the feature list is based on Gammatone subspace analysis and Linear Prediction Error Filters (LPEFs). As a ï¬nal step on the system, the application of a model that approximates the tempo perception by human listeners is proposed. The results of the evaluation indicate the proposed method compares favourably with other, state-of-the-art tempo estimation methods, using only one frame of the musical experts when most of the literature methods demand the processing of the whole piece
Notes:
2010
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Masters theses

1998
1997

PhD theses

2001
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