Objective: Because exhalation causes the vocal cords to passively vibrate, there appears to be some correlation between aerodynamic parameters and various parameters. The present study investigated the relationship between vocal cord vibration parameters and aerodynamic parameters.

Method: Testing was performed on 13 patients with various voice disorders. Observations of the vocal cord vibration were conducted using a high-speed video system (Kay). Subjects were instructed to vocalize the vowel sound /a/ at a comfortable pitch and intensity. The predetermined area was analyzed for 20 cycles. Images taken at a speed of 2000 frames/s were analyzed using Kay Image Processing Software (KIPS). Using the airway interruption method, the phonatory function analyzer PS77E was used to measure sound pressure level (SPL), mean flow rate, expiratory lung pressure, and airway resistance. The present study was approved by the ethics review board and informed consent was obtained. Interrelations among the parameters were investigated by Fisher r-to-Z transformation with the level of significance set at p<0.05.

Results: A correlation existed between SPL and posterior glottal vibration as assessed by kymograph edge analysis (KEA) (left: p=0.0199 and right: p=0.0372) and central glottal vibration (left: p=0.022 and right: p=0.0438). A negative correlation was seen between airway resistance and glottal area waveform (GAW) minimum opening (p=0.0256). A correlation existed between airway resistance and KEA glottal closure (posterior glottis: p=0.003; central glottis: p=0.0377; anterior glottis: p=0.0311).

In most cases vocal changes after operations on the thyroid gland are connected with the trauma of the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN). The preservation of the larynx functions can be improved with the use of the intraoperative neuromonitoring.

The vocal function have been assessed among 82 patients after surgical operation on the thyroid gland. 105 RLNs and EBSLNs have been at risk of surgical trauma. During the operation we have been using Neurosine 100 and surgical microscope for RLN and EBSLN identification.  The survey of laryngeal nerve function has been carried out before and after operation. Electromyography (EMG), videolaryngostroboscopy, perceptual analysis of dysphonia and spectrographic voice analysis have been also carried out.

Results: 104 RLNs and 86 EBSLNs have been successfully identified. The vocal changes are typical of 23% of patients   after thyreoidectomy and 12% of patients after hemithyroidectomy.  Unilateral larynx paresis was typical of the 3 patients, 1 patient had the permanent one. These damages have been diagnosed with the use of the standard indirect laryngoscopy.

The 18 patients have had the postoperative changes after the use of EMG of cricothyroid muscle; the 4 patients had the bilateral ones. The postoperative changes of 6 patients have been found out more than 6 months after surgery.

 After videolaryngostroboscopy the damages of the glottis closure at the phonation have been revealed among 7 patients, in 6 months they remained in 5 cases.

The changes connected with the middle voice pitch reduction more then 5% of preoperative size have been found out among 20 patients, after 6 months they have been found out among   7 patients.   

Conclusion: The significant correlation has been found between spectrographic voice analysis and EMG. To our mind, it seems reasonable to assume that the degree of glottis insufficiency caused by the laryngeal nerve damages is associated with the aspirate dysphonia, a low harmonic- noise coefficient, and reduced middle voice pitch.

The tendency to increase in different diseases of the vocal device of the professionals of the voice is connected both with non-observance of  the voice hygiene and with  the increase in the vocal loading among the  certain professional categories.

In this connection the purpose of our research was to estimate the efficiency of the application of the pulsatile electrostatic field for the prevention of  the voice disturbances in the condition of the raised vocal loading

Materials and methods: we have examined 9 TV journalists and sports commentators of the different television channels. Specificity of their work consists of   an extremely high voice loading, a high emotionality during the commentaries of the  sports matches or  when they spend too much time in the professional business trips. The last  thing  defines  the complexity of the prophylactic medical examination and impossibility of getting the timely treatment in case of onset of the vocal problem. All examined patients  complained about the hoarseness and fatigability of the voice after high voice loading during the day for a period of  3-7 days or 2,5 weeks during   the Olympic Games. During the Olympic Games in Beijing and television competition «the Eurovision 2008» the  prophylactic therapy was carried out with the application of the device Hivamat 200" (which  is comfortable for  using  in a trip because of its small size).

The work  of the device  is based on the action of  the pulsatile bi-phase electrostatic field which is created between the manual gauge and the patient. In the area of the local influence on the larynx  the depolarization of  electrically neutral molecules occurs. As a result of it   there is an intensive resonant vibration of the  tissues with the  frequency from 5 to 200 Hz.

This effect leads to  antiedematic,  anaesthetic, , regenerative   influence. During the examination the patients  filled in the questionnaire to estimate their  sensations, they estimated in marks the  dynamics of the voice condition. We  have written the individual program on a smart card for each patient. These procedures have been carried out  daily, at  the end of the working day, or in addition, in case of hoarseness and fatigability of the voice at  the end of translation.

As a result of  the prevention all patients have noticed the significant  increase in the tolerance of the vocal device, and the decrease in frequency of  hoarseness occurrence.

Conclusion: the obtained data  have shown the  effectiveness of using the method of the  pulsatile electrostatic field for recovery of the normal condition and  the maintenance of the tonus of the muscles of the vocal device among the  professionals of the voice in the condition of the raised vocal loading.

This study investigated the acoustic and perceptual characteristics of a good shouting voice. A total of 35 males shouted a short monolog (an excerpt of Shakespeare‘s King Lear) in a studio. Their lowest possible tone (produced in soft voice, vocal fry excluded) was also measured. The recorded shouting samples were analyzed for mean fundamental frequency (F0), equivalent sound level (Leq), difference between the average Leq of the 1-5kHz region and the average Leq of the 50Hz-1kHz region (‘alpha ratio'), loudness (in sones) and difference between the average level of the F1 region and the average level of the F0 region (L1-L0). Long-term-average spectra (LTAS) were made. The relative F0 (difference between the lowest possible F0 and the mean F0 in shouting, measured in semitones) was also calculated. Nine listeners, trained in vocology, evaluated the samples for voice quality, timbre, perceived pitch, perceived loudness, firmness of phonation (along the axis from breathy to pressed), degree of turbulence noise, and roughness. Reliability between the listeners' evaluations was good (Cronbach's alpha 0,80-0,94). Lack of hypertension, perceived noise and roughness correlated with voice quality. Alpha ratio, firmness, Leq and F0 seemed to be related to perceived loudness. The main characteristics in good shouting voice, thus, seemed to be lack of perceived noise, lack of roughness, great alpha ratio, great Leq and appropriate firmness.

Key words: shouting, loudness, voice quality, perceptual evaluation, long-term average spectrum