Kai Xiao , pp. 54. TEK/avd. för signalbehandling, 2008.
Human echolocation is the way in which people use information in echoes to
detect objects and locate themselves. Previous research were done in order to
investigate this complex processing. One on-going research is based on empirical
results of both blind and sighted people, and tries to set up the relations between
behavioral data and physical analysis.
Repetition pitch and loudness are two of the mechanisms which human echolocation
is based on. People’s perception of repetition pitch and loudness has been found to be
strongly related to autocorrelation and the root mean square value of the sound signal
respectively. This thesis project was conducted in order to analyze the relevant
information in previously made sound recordings. By comparing theoretical results,
some important sound properties were identified. Colorations in the original sound
recordings were found to be able to influence participants’ judgments on echoes.
An acoustic model was set up in order to synthesize sound recordings with
pre-defined properties. Physical results of autocorrelation and root mean square value
of the synthesized sound signals were validated to follow the theoretical expectations.
Discussions and proposals were made in order to further improve the sound syntheses’
correspondence to physical recordings.
The main achievements in this thesis project were to provide analysis from signal
processing’s point of view in order to identify sound properties, to investigate
relations between physical results and empirical results of human echolocation and to
propose an acoustic model to synthesis sound.