New linear predictive methods for digital speech processing

Speech processing is needed whenever speech is to be compressed, synthesised or recognised by the means of electrical equipment. Different types of phones, multimedia equipment and interfaces to various electronic devices, all require digital speech processing. As an example, a GSM phone applies speech processing in its RPE-LTP encoder/decoder (ETSI, 1997). In this coder, 20 ms of speech is first analysed in the short-term prediction (STP) part, and second in the long-term prediction (LTP) part. Finally, speech compression is achieved in the RPE encoding part, where only 1/3 of the encoded samples are selected to be transmitted. This thesis presents modifications for one of the most widely applied techniques in digital speech processing, namely linear prediction (LP). During recent decades linear prediction has played an important role in telecommunications and other areas related to speech compression and recognition. In linear prediction sample s(n) is predicted from its p previous samples by forming a linear combination of the p previous samples and by minimising the prediction error. This procedure in the time domain corresponds to modelling the spectral envelope of the speech spectrum in the frequency domain. The accuracy of the spectral envelope to the speech spectrum is strongly dependent on the order of the resulting all-pole filter. This, in turn, is usually related to the number of parameters required to define the model, and hence to be transmitted. Our study presents new predictive methods, which are modified from conventional linear prediction by taking the previous samples for linear combination differently. This algorithmic development aims at new all-pole techniques, which could present speech spectra with fewer parameters.reviewe

Effects of force magnitude on dental arches in cervical headgear therapy

acceptedVersionPeer reviewe

The impact of force magnitude on the first and second maxillary molars in cervical headgear therapy

Aim: To study the effect of force magnitude on the maxillary first and second molars in cervical headgear (CHG) therapy. Material and methods: In this controlled clinical trial, patients (n = 40) were treated with CHG with a light (L, 300 g, n = 22) or a heavy force (H, 500 g, n = 18) magnitude. The subjects were asked to wear CHG for 10 hours a day for 10 months. The outer bow of the CHG facebow was lifted up for 10-20 degrees and the inner bow was expanded 3-4 mm. Adherence to instructions and force magnitude were monitored using an electronic module (Smartgear, Swissorthodontics, Switzerland). Panoramic and lateral radiographs before (T1) and after treatment (T2) were analysed using a Romexis Cephalometric module (Planmeca, Finland) focussing on the angular, sagittal, and vertical positions of the permanent first and second molars. Results: According to the cephalometric analysis of the maxillary first and second molars, distal tipping occurred during T1-T2 in the H group (P = 0.010 and 0.000, respectively), and the change was greater in the H group compared to the L group (P = 0.045 and 0.019, respectively). Based on the panoramic analysis, tipping occurred in the distal direction during therapy in the H group in the second molars compared to the midline or condylar line (P = 0.001 and 0.001; P = 0.008 and 0.003 on the right and left, respectively). Conclusion: With heavy force magnitude, the maxillary first and second molars can tilt more easily in the distal direction even if the CHG was used less. Distal tipping of the molar can be considered to be a side effect of CHG therapy.acceptedVersionPeer reviewe

Effects of force magnitude on dental arches in cervical headgear therapy

Abstract Aim: To study the influence of different force magnitudes on dental arches in cervical headgear (CHG) treatment. Material and methods: In this controlled clinical trial, patients (n = 40) were treated with CHG with light (L, 300 g, n = 22) or heavy force (H, 500 g, n = 18) magnitude. Subjects were asked to use CHG for 10 hours a day for 10 months. The outer bow of the CHG facebow was raised 10–20 degrees and the inner bow expanded 3–4 mm. Adherence to instructions and force magnitude were monitored with an electronic module (Smartgear, Swissorthodontics, Switzerland). Impressions for study models were taken before (T1) and after (T2) treatment and the study models were scanned into digital form (3Shape, R700 Scanner, Denmark). Measurements were made using the digital models (Planmeca Romexis, Model analyser, Finland). Results: During the treatment (T1–T2) the upper inter-canine distance increased by 2.83 mm (P = 0.000) and 2.60 mm (P = 0.000) in the L and H force magnitude groups, respectively. Upper inter-molar width increased by 3.16 mm (P = 0.000) and 2.50 mm (P = 0.000) in the L and H groups, respectively. Maxillary total arch perimeter increased by 6.39 mm (P = 0.001) and 6.68 mm (P = 0.001) in the L and H groups, respectively. In the amount of change over time, T1–T2, in the upper arch measurements, no significant difference was found between the groups. Lower inter-canine width increased by 0.94 mm (P = 0.005) and 1.16 mm (P = 0.000) in the L and H groups, respectively; no difference between the groups. Lower inter-molar distance increased by 2.17 mm (P = 0.000) and 1.11 mm (P = 0.008) in the L and H groups, respectively. At the end of the study, upper and lower inter-molar width was larger in the L group than in the H group (P = 0.039 and P = 0.022, respectively). Conclusions: CHG therapy is an effective method for expanding and releasing moderate crowding of the upper dental arch. The lower arch spontaneously follows the upper arch in widening effects, and minor expansion can also be seen on the lower arch. In the L group, larger inter-molar width was achieved on the upper and lower arch; probably due to better adherence to instructions. Light force is recommended for use in CHG therapy

The impact of force magnitude on the first and second maxillary molars in cervical headgear therapy

Abstract Aim: To study the effect of force magnitude on the maxillary first and second molars in cervical headgear (CHG) therapy. Material and methods: In this controlled clinical trial, patients (n = 40) were treated with CHG with a light (L, 300 g, n = 22) or a heavy force (H, 500 g, n = 18) magnitude. The subjects were asked to wear CHG for 10 hours a day for 10 months. The outer bow of the CHG facebow was lifted up for 10–20 degrees and the inner bow was expanded 3–4 mm. Adherence to instructions and force magnitude were monitored using an electronic module (Smartgear, Swissorthodontics, Switzerland). Panoramic and lateral radiographs before (T1) and after treatment (T2) were analysed using a Romexis Cephalometric module (Planmeca, Finland) focussing on the angular, sagittal, and vertical positions of the permanent first and second molars. Results: According to the cephalometric analysis of the maxillary first and second molars, distal tipping occurred during T1–T2 in the H group (P = 0.010 and 0.000, respectively), and the change was greater in the H group compared to the L group (P = 0.045 and 0.019, respectively). Based on the panoramic analysis, tipping occurred in the distal direction during therapy in the H group in the second molars compared to the midline or condylar line (P = 0.001 and 0.001; P = 0.008 and 0.003 on the right and left, respectively). Conclusions: With heavy force magnitude, the maxillary first and second molars can tilt more easily in the distal direction even if the CHG was used less. Distal tipping of the molar can be considered to be a side effect of CHG therapy