[dipl] Perustieteiden korkeakoulu / SCI

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Browsing [dipl] Perustieteiden korkeakoulu / SCI by Degree programme/Major subject "Akustiikka ja äänenkäsittelytekniikka"

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  • Analysis of human voice production using inverse filtering, high-speed imaging, and electroglottography
    (2005) Pulakka, Hannu
     Master's thesis
    Human voice production was studied using three methods: inverse filtering, digital high-speed imaging of the vocal folds, and electroglottography. The primary goal was to evaluate an inverse filtering method by comparing inverse filtered glottal flow estimates with information obtained by the other methods. More detailed examination of the human voice source behavior was also included in the work. Material from two experiments was analyzed in this study. The data of the first experiment consisted of simultaneous recordings of acoustic speech signal, electroglottogram, and high-speed imaging acquired during sustained vowel phonations. Inverse filtered glottal flow estimates were compared with glottal area waveforms derived from the image material by calculating pulse shape parameters from the signals. The material of the second experiment included recordings of acoustic speech signal and electroglottogram during phonations of sustained vowels. This material was utilized for the analysis of the opening phase and the closing phase of vocal fold vibration. The evaluated inverse filtering method was found to produce mostly reasonable estimates of glottal flow. However, the parameters of the system have to be set appropriately, which requires experience on inverse filtering and speech production. The flow estimates often showed a two-stage opening phase with two instants of rapid increase in the flow derivative. The instant of glottal opening detected in the electroglottogram was often found to coincide with an increase in the flow derivative. The instant of minimum flow derivative was found to occur mostly during the last quarter of the closing phase and it was shown to precede the closing peak of the differentiated electroglottogram.
  • Structural analysis of recorded music
    (2020-01-20) Saikkonen, Lauri
     Perustieteiden korkeakoulu | Master's thesis
    Structural analysis of music is one sub field of music information retrieval. The objective of structural analysis of music is to segment the audio into musically meaningful temporal segments. Finding relations between those different segments is also of interest when analysing structure. Using these relations - especially similarities - between different segments can be utilised to try to improve other music information retrieval algorithms. The objective of this thesis is to take a look into some of the state of the art methods for music structure analysis and find out if automatic chord transcription can be improved using these methods. In total, three different methods are examined and different strategies for chord transcription improvement are introduced. The results of this thesis indicate that the structure of music can be automatically analysed to an extent but not at the level of a human expert. The results also show that it is very difficult to improve current state of the art automatic chord transcription using information from a structural analysis algorithm. A more robust and granular structural analysis algorithm could in theory provide improvements to automatic chord transcription.
  • Studies on parametric reverberation of a concert hall
    (2010) Beckmann, Bjarne
     School of Science | Master's thesis
    This work investigates complex decays, which are created virtually with reverberation algorithms. For this purpose, the appropriateness of these acoustical environments is studied in connection with different types of classical music. Several types of artificial reverberation are created and added to anechoic recordings. Through a listening test and analysis of objective measurements and their parameters, the qualities of ambience are evaluated. There exist clearly audible differences between settings with similar objective measures. Dual-decay styled reverberation is not only used in the recording industry, but has gained popularity also in the field of concert hall acoustics. Dual-decay systems do not only exist when enhancing electronically the acoustics of an existing hall, but do also occur in concert halls with coupled spaces, when incorporating reverberation chambers or directed early reflections. The results of the listening test were signal dependent. Romantic music with a big orchestra, such as Bruckner, works best in a reverberant spacious hall, which features long reverberation at a high level. A medium level of reverberation with strong reflections at 100 - 140 ms, coming from the frontal and lateral sides is suitable for Mozart. The objective measures of ISO 3382 do not explain the differences between the samples.