Headphone Audio and Augmented Reality

The concept of augmented reality audio (ARA) characterizes techniques where physically real sound and voice environment is extended with various virtual environments and communication scenarios. In this project, the focus is in developing new techniques, applications, and interfaces for future personal appliances which are wearable and support full-duplex high-quality audio and voice transmission.

Selected Publications

Publication Short Description

J. Rämö and V. Välimäki, "Digital Augmented Reality Headset," Journal of Electrical and Computer Engineering, Vol. 2012, Article ID 457374, 13 pages, 2012. doi:10.1155/2012/457374.

 This paper proposes digital IIR filters to realize the required equalization and evaluates a real-time prototype of a digital ARA system.
S. Oksanen, M. Hiipakka. and V. Sivonen, "Estimating Individual Sound Pressure Levels at the Eardrum in Music Playback over Insert Headphones," in AES 47th International Conference, Chicago, USA, June 2012. In this paper, insert headphones with in-built miniature microphones and acoustic modeling to estimate individual eardrum sound pressure from the microphone signals were used in assessing music playback levels.
J. Rämö and V. Välimäki, "Signal Processing Framework for Virtual Headphone Listening Tests in a Noisy Environment," in AES 132nd Convention, Budapest, Hungary, April 2012.

This article introduces a signal processing framework, which enables parallel evaluation of headphones in a virtual listening test. Furthermore, the framework allows a noise signal to be fed through a filter simulating the ambient sound isolation at the same time when the sound quality of the headphones is evaluated.

J. Rämö, V. Välimäki, M. Alanko, and M. Tikander, "Perceptual Frequency Response Simulator for Music in Noisy Environments," in AES 45th International Conference, Espoo, Finland, March 2012.

 The perceptual simulator utilizes auditory masking models and the isolation capabilities of different headphones to simulate the auditory masking phenomenon in headphone listening.

G. Lorho, "Perceived Quality Evaluation: An Application to Sound Reproduction over Headphones," Ph.D. Thesis, Aalto University, School of Science and Technology, Department of Signal Processing and Acoustics, Espoo Finland, June 2010.

 This thesis focuses in the topic referred to as 'sensory analysis' and explores more specifically two different types of sensory techniques. Sound reproduction over headphones is the application considered in this investigation on sensory analysis.

M. Hiipakka, M. Tikander, and M. Karjalainen, "Modeling the External Ear Acoustics for Insert Headphone Usage," Journal of the audio engineering society, 2010. Vol. 58, No 4, pp. 269-281.

 The results of this article are relevant for designing insert earphones that are to be used in binaural and auralization situations.
M. Tikander, "Development and Evaluation of Augmented Reality Audio Systems," Ph.D. Thesis, Helsinki University of Technology, Department of Signal Processing and Acoustics, Espoo, Finland November 2009. This work focuses on the concept of using an insert-type of headset with integrated microphones as a platform for ARA applications and environments.  Subjective and objective measurements were performed to yield optimum equalization for the headset design. The sound quality and usability of the system is further evaluated in laboratory and real-life situations.
J. Rämö, "Evaluation of an Augmented Reality Audio Headset and Mixer," Master’s Thesis, Helsinki University of Technology, Faculty of Electronics, Communications and Automation, Department of Signal Processing and Acoustics, Espoo, Finland, May 2009.

This thesis performes full-scale laboratory measurements and an usability evaluation of the ARA hardware. The objective was to collect technical data about the hardware
and to gather knowledge concerning how users perceive the usability of the ARA headset in everyday-life situations. 
M. Tikander, "Usability Issues in Listening to Natural Sounds with an Augmented Reality Audio Headset," Journal of the audio engineering society, 2009. Vol. 57, No. 6, pp. 430-441. Study on usability issues when a person is using the augmented reality headset in their everyday life.

M. Tikander, M. Karjalainen, and V. Riikonen, "An augmented reality audio headset," in Proceedings of the DAFx-08, pp. 181-184, Espoo, Finland, September 1-4. 2008.

 This paper introduces an ARA headset, equalization of its response, and particularly the results of a usability study. 

V. Riikonen, M. Tikander, and M. Karjalainen, "An Augmented Reality Audio Mixer and Equalizer," The 124th AES Convention, Amsterdam, Netherlands, May 17-20, 2008.

 This paper presents a novel augmented reality audio mixer with real-time analog equalization to correct the coloration caused by the leakage through the headset and changed resonances in the closed ear canal. 
V. Riikonen, "User-related Acoustics in a Two-way Augmented Reality Audio System," Master’s Thesis, Helsinki University of Technology, Faculty of Electronics, Communications and Automation, Department of Signal Processing and Acoustics, Espoo, Finland, April 2008.

The main issues discussed in this thesis are the sound quality of the pseudoacoustic representation, the rendering of the virtual sound images in a controlled manner, and augmented reality audio platform development.
M. Tikander, "Modeling the attenuation of a loosely-fit insert headphone for augmented reality audio", In Proceedings of the 30th AES Conference, Saariselkä, Finland, 15-17 March 2007.

The paper studies how a traditional (walkman-type) earphone attenuates surrounding sounds. An electric equivalent circuit is introduced to model sound leaking through the headphone and around the headphone into the ear canal. This model can be used when designing acoustically transparent ARA-headphones.  
M. Tikander, "Sound quality of an augmented reality audio headset", In Proceedings of The 8th International Conference on Digital Audio Effects, DAFx'05, Madrid, Spain, 20-22 September 2005.

An introduction to aspects having effect on ARA-headset sound quality. Article also shows the results of a listening test that was conducted to see how well non-individualized equalization works to improve the sound quality of a headset.  
A. Härmä, J. Jakka, M. Tikander, M. Karjalainen, T. Lokki, J. Hiipakka, and G. Lorho, "Augmented reality audio for mobile and wearable appliances", Journal of the Audio Engineering Society (JAES), Vol. 52, No. 6, pp. 618-639, June 2004. An overview of Augmented Reality Audio -related technologies.  

M. Tikander, A. Härmä, and M. Karjalainen, "Acoustic positioning and head tracking based on binaural signals", 116th AES Convention, preprint 264, Berlin, Germany, 8 - 11 May 2004.

 Summarizes different binaural positioning scenarios, and also different techniques to estimate the user's position and orientation. Different kinds of anchor signals and signal processing is also studied.
T. Lokki, H. Nironen, S. Vesa, L. Savioja, A. Härmä, and M. Karjalainen, "Application scenarios of wearable and mobile augmented reality audio,"  In the AES 116th International Convention, Berlin, Germany, May 8-11, 2004, preprint nr. 6026. An overview of different ARA-related applications.
M. Karjalainen, M. Tikander, and A. Härmä, "Head-tracking and subject positioning using binaural headset microphones and common modulation anchor sources", in Proceedings of the ICASSP'2004, Montreal, Canada, 17-21 May, 2004. The head-tracking and positioning introduces in the previous paper is further improved. The known signals that are played from the anchors, and are use for positioning, are modulated up to higher frequency bands. This way multiple anchors can be used and detected simultaniously. Using higher frequencies (>15 Hz) has some other benefits as well.
M. Tikander, A. Härmä, M. Karjalainen, "Binaural positioning system for wearable augmented reality audio", in Proceedings of the IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA'03), New Paltz, New York, USA, October 2003.

A binaural positioning method is introduced where there are some known sound sources (anchors) in the environment. By cross-correlating the binaural microphone signals with the known anchors the distance to each anchor can be estimated. 
A. Härmä, J. Jakka, M. Tikander, M. Karjalainen, T. Lokki, H. Nironen, and S. Vesa, "Techniques and applications of wearable augmented reality audio",the 114th Convention of Audio Eng. Soc., Amsterdam, Netherlands, March 22-25, 2003. An introduction to wearable augmented reality audio (WARA) technology. Various technical and usability aspects are discussed and many kinds of application scenarios are tested.
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