### Concept of Voice Onset Time  
An assessment of voice onset is an integral part of perceptual evaluation in a variety of diagnostic concepts, and is commonly described as vocal attack (rated as soft, breathy, or harsh) [17; 18]. The quality of the voicing onset potentially adds information about vocal control and the vibratory behavior of the vocal folds. An objective feasible way to measure vocal onset could improve clinical voice assessment [19].  
Voice Onset Time (VOT) is an acoustic measure of the temporal domain. Its calculation relies on the onset of voicing to phonologically distinguish between voiceless [p, t, k] and voiced [b, d, g] stop consonant productions [20; 21]. Studies in Brazilian Portuguese (BP) have pointed out that VOT objectively discriminates voicing features (voiced versus voiceless) and place of articulation (bilabial, alveolar, and velar) [22; 23], in consonance with other languages, for example, English [23; 24; 25; 26]. VOT has been shown to be influenced by a variety of factors, including language-specific rules, phonetic environment, and prosody [20; 27]. Moreover, BP language, the vowel environment, syllable stress, and syllable position may affect VOT [22; 23; 25]. Thus, these aspects should be considered when interpreting VOT data. Data from BP voiceless bilabial stop [p] productions have shown a VOT duration with a large natural range from 6.90 ms to 28.30 ms [22].  
In addition, physiological factors can influence VOT measurements. General voice onset differences related to the place of articulation and voicing depend on numerous factors, such as aerodynamic forces, articulatory movements, and differences in the mass of articulators [20]. Therefore, disturbed phonation involving an imbalance of muscular tension and altered aerodynamic functions, vocal fold mass and stiffness, and articulatory movements or position all have the potential to impact VOT.  
Studies carried out on healthy voices have shown that VOT duration in voiceless stop production decreases with increasing pitch [10; 27]. The physiological hypothesis is that increased tension in the intrinsic laryngeal musculature related to higher _f_o leads to a decrease in glottal abduction amplitude, reducing VOT duration. In a recent study, [PERSON] et al. [10] explored the relation between _f_o, self-reported vocal strain, and vocal effort in a group of sixteen vocally healthy speakers of both genders. The results confirmed that an increase in _f_o leads to a decrease in VOT duration in voiceless stop production embedded in a carrier phrase. However, these results were not confirmed for the characteristics of strain and vocal effort. In addition, despite SPL rising in both conditions (vocal effort and strain), there was no significant effect on VOT. The authors concluded that vocal effort and strain in typical speakers may be associated with individually different voice techniques and that a temporary increase in vocal effort may be associated with different underlying muscular adjustments as in patients with chronic vocal hyperfunction (VH). This reinforcesthe hypothesis that VH is related to complex adjustments of intrinsic and extrinsic laryngeal muscles exhibiting recurrent patterns during a certain period of time [5].