The collision threshold pressure (CTP), i.e. the smallest amount of subglottal pressure needed for vocal fold collision, has been explored as a possible complement or alternative to the now commonly used phonation threshold pressure (PTP), i.e. the smallest amount of subglottal pressure needed to initiate and sustain vocal fold oscillation. In addition, the effects of vocal warm-up (Paper 1) and vocal loading (Paper 2) on the CTP and the PTP have been investigated. Results confirm previous findings that PTP increases with an increase in fundamental frequency (F0) of phonation and this is true also for CTP, which on average is about 4 cm H₂O higher than the PTP. Statistically significant increases of the CTP and PTP after vocal loading were confirmed and after the vocal warm-up, the threshold pressures were generally lowered although these results were significant only for the females. The vocal loading effect was minor for the two singer subjects who participated in the experiment of Paper 2.

In Paper 3, the now commonly used audio spectral tilt (AST) is measured on the vowels of a large database (5277 sentences) containing speech of one male Swedish actor. Moreover, the new measure electroglottographic spectral tilt (EST) is calculated from the derivatives of the electroglottographic signals (DEGG) of the same database. Both AST and EST were checked for vowel dependency and the results show that while AST is vowel dependent, EST is not.

Paper 4 reports the findings from a perception experiment on Swedish accents performed on 47 Swedish native speakers from the three main parts of Sweden. Speech consisting of one sentence chosen for its prosodically interesting properties and spoken by 72 speakers was played in headphones. The subjects would then try to locate the origin of every speaker on a map of Sweden. Results showed for example that the accents of the capital of Sweden (Stockholm), Gotland and southern Sweden were the ones placed correctly to the highest degree.