Reading, after a certain age, diverts the mind too much from its creative pursuits. Any man who reads too much and uses his own brain too little falls into lazy habits of thinking.
Albert Einstein
In january 2002 I started graduating at the TU Delft. I obtained my degree in August 2003. My study was Applied Physics, my group works on Acoustics.

Mostly all research carried out within the group deals with array technology. Main research topics are spatial sound reproduction, based on the concept of Wave Field Synthesis (WFS) and microphone array technology for the directional recording and analysis of audio and noise.

Transform coding of audio impulse responses

The goal of this research is to develop a coding structure which allows thecompression of impulse responses to a ratio much higher than current audiocoders or the algorithm by Sonke. The compression type is lossy, which meansthat the coded version of the impulse response will not contain all informationof the original. The amount of reduction that can be reached depends on two principles. The first is based on the characteristics of the human hearingsystem. A time-frequency analysis is done to compare the impulse response topsychoacoustic masking properties of the human ear, just as in audio coders.

Coded impulse responses

Secondly the characteristics of impulse responses are used to reach a meaningfulreduction of data, by discriminating between the various parts of a impulseresponse such as the direct sound, early reflections and the reverberation. Thisis done by carefully constructing a filter bank. In our model there will befree parameters, such as the number of frequency bands, the size of the windows and the quantization of the parameters which effect the quality of the compression. The difference between the compressed and the original impulse responses will be perceptually evaluated with listening tests.

The proposed model must be able to apply to a wide range of impulse responses(measured and artificially constructed) and must be practical in use. Thusencoding speed on mode computers must be of the order of magnitude ofreal-time and decoding must be even faster than real-time.

You can download my final report. I also held a presentation about this topic. My sheets (in PDF) can be downloaded in color or black/white here.If you want to do something related to my work, feel free to contact me.

Posted by jochem on 2003-08-03, last update on 2003-08-03