Phonation threshold pressure (PTP), frequently used for characterizing vocal fold properties, is often difficult to measure. This investigation analyses the lowest pressure initiating vocal fold collision (CTP). Microphone, electroglottograph (EGG), and oral pressure signals were recorded, before and after vocal warm-up, in 15 amateur singers, repeating the syllable /pa:/ at several fundamental frequencies with gradually decreasing vocal loudness. Subglottal pressure was estimated from oral pressure during the p-occlusion, using the audio and the EGG amplitudes as criteria for PTP and CTP. The coefficient of variation was mostly lower for CTP than for PTP. Both CTP and PTP tended to be higher before than after the warm-up. The results support the conclusion that CTP is a promising parameter in investigations of vocal fold characteristics.

Purpose: Resonance tube phonation in water (RTPW) or in air is a voice therapy method successfully used for treatment of several voice pathologies. Its effect on the voice has not been thoroughly studied. This investigation analyzes the effects of RTPW on collision and phonation threshold pressures (CTP and PTP), the lowest subglottal pressure needed for vocal fold collision and phonation, respectively.

Method: Twelve mezzo-sopranos phonated into a glass tube, the end of which was placed under the water surface in a jar. Subglottal pressure, electroglottography and audio signals were recorded before and after exercise. Also, the perceptual effects were assessed in a listening test with an expert panel which also rated the subjects’ singing experience.

Results: Resonance tube phonation significantly increased CTP, and also tended to improve perceived voice quality. The latter effect was mostly greater in singers who did not practice singing daily. In addition, a more pronounced perceptual effect was found in singers rated as being less experienced.

Conclusion: Resonance tube phonation significantly raised CTP and tended to improve perceptual ratings of voice quality. The effect on PTP failed to reach significance.

The phonation threshold pressure (PTP) is defined as the lowest subglottal pressure needed for obtaining and sustaining vocal fold oscillation. It has been found to increase during vocal fatigue. In the present study, PTP is measured together with the threshold pressure needed for vocal fold collision; henceforth, the collision threshold pressure (CTP). PTP and CTP are compared before and after loud, prolonged vocalization in singer and nonsinger voices. Ten subjects repeated the vowel sequence /a, e, i, o, u/ at a Sound Pressure Level of at least 80 dB at 0.3 m for 20 minutes. Audio and electroglottography signals were recorded before and after this exercise. At the same time, oral pressure was registered while the subjects produced a diminuendo repeating the syllable /pa:/, thus acquiring an approximate of the subglottal pressure. CTP and PTP increased significantly after the vocal loading in the nonsinger subjects. On the other hand, singers reported no substantial effect of the exercise, and most singers had a mean after-to-before ratio close to 1 for both CTP and PTP.

Collision threshold pressure (CTP), i.e., the lowest subglottal pressure producing vocal fold contact during phonation, is a parameter likely to reflect relevant vocal fold properties. The amplitude of an electroglottographic (EGG) signal or the amplitude of its first derivative (dEGG) has been used as the criterion of such contact. Manual measurement of CTP is time-consuming, making the development of a simpler, alternative method desirable. In this investigation we compare CTP values automatically derived from the dEGG signal to values measured manually, and to values derived from a set of alternative parameters, some obtained from audio and some from EGG signals. One of the parameters was the novel EGG wavegram, which visualizes sequences of EGG or dEGG cycles, normalized with respect to period and amplitude. Raters with and without previous acquaintance with EGG analysis marked the disappearance of vocal fold contact in dEGG and in wavegram displays of /pa:/-sequences produced with continuously decreasing vocal loudness by seven singer subjects. Vocal fold contact was equally accurately identified in displays of dEGG amplitude as of wavegram. Automatically derived CTP values showed high correlation with those measured manually, and with those derived from the ratings of the visual displays. Seven other parameters were tested as criteria of such contact. Mainly due to noise in the EGG signal, most of them yielded CTP values differing considerably from those derived from the manual and the automatic methods, while the EGG spectrum slope showed a high correlation. The possibility of measuring CTP automatically seems promising for future investigations.