Research

At the department we work in several fields of acoustics but focus mainly on issues related to human sound perception and electroacoustics.
Every second year the university publish a Research Report, one for each institute.
Below you'll find some of our current and past research activities (short version of the Research Report mentioned).
Please note that this list of activities is not entirely up to date. However, if you go to our list of publications you will find that this page is completely up to date.



Apart from the activities mentioned below, we also have a few large-scale projects/programmes which are primarily externally funded.

Sound Quality Research Unit



To projekter med projektbeskrivelser på dansk (two projects described in Danish):
Undersøgelse af støj fra vindmøller og kraftvarmeværker
Investigation of noise from wind turbines and local heating/electricity power plants
Projekt om genevirkninger af lavfrekvent støj
Project on annoyance from low frequency noise


Distance perception  How does human hearing judge distance to the sound source? In this project a large body of experiments were conducted in order to investigate how well human hearing judge distance. The main result was, that reflections from the surroundings play a dominant role in distance perception. 

Sound transmission to and within the ear canal 
A theoretical and experimental analysis of how sound is transmitted to and within the human ear canal. A sound transmission model is made and verified by measurements. This model is used for improving binaural recording techniques. 

A loudspeaker with controlled directivity 
A loudspeaker box usually contains several loudspeakers because a large diaphragm area is preferable at low frequencies, while a small area is best at high frequencies. At low frequencies a lot of air has to be moved, which calls for a large diaphragm area, but large diaphragms tend to break up at high frequencies. The aim of this project was to construct a loudspeaker with controlled breakup and directivity by experimenting with different membrane geometries. 

Artificial head techniques for noise evaluation 
Traditional noise measurements determine sound pressure level or sound intensity using ordinary microphones. These measurements fail to take the directional dependent amplifications of the human head into account, and may thus be very inaccurate as measures of noise exposure. In this project artificial head techniques are investigated and meaningful assessment methods for comparison of noise sources using artificial heads are developed. 

Designing an optimal artificial head 
The quality of the existing artificial (dummy) heads are evaluated objectively and subjectively; errors and imperfections are identified and an alternative approach is developed. The goal is to design a scientifically optimal dummy head for use in binaural recording and noise evaluation. 

Binaural auralization: Generating correct impressions of sound sources in rooms 
Knowledge of sound transmission to and within the ear canal is used for artificial generation of binaural signals through digital signal processing. The purpose is to make it possible to listen to e.g. a concert hall before it is built, or to loudspeaker systems during the development process. 

SCATIS: Spatially Coordinated Auditory/Tactile Interactive Scenario 
Existing Virtual Reality (VR) systems usually focus on the visual sense, and more or less neglect the other senses. In this project the auditory and tactile senses received full attention. A laboratory system for research of the interaction between touch and hearing was developed. 

Methods for designing and measuring headphones 
How does the perfect headphone sound? This is not a trivial question. In this project different design goals for headphones are developed, as well as reliable measurement methods. 

Multiprocessor DSP system for digital audio 
Many signal processing algorithms for digital audio can with advantage be implemented in a parallel structure. A multiprocessor DSP system with standard audio interfaces is developed, together with a debugger/monitor system allowing to debug on all processors simultaneously. 

Veridical sound for virtual reality systems 
The sound in existing virtual reality systems is not very convincing. The possibilities for improvement using binaural auralization is investigated. Virtual reality sound have several applications besides VR systems, e.g. cockpit communication systems, teleconferencing and man machine interfaces for process control and robot control. 

Methods for testing human hearing 
Methods for determination of hearing thresholds - monaural as well as binaural - are investigated, and hearing threshold data are gathered. The new methods are compared to existing calibration methods for headphones for clinical hearing threshold measurements and are evaluated by a clinical example - "Does use of walkmen damage hearing?" 

Low frequency loudness level contours 
Knowledge of the human loudness level contours are essential in many areas of noise and audiology. Existing standards are currently being revised in ISO/TC43/WG1, and a substantial body of new data is thus being collected and compared with existing loudness level measurements.

Last modified March 27th 2000