# Auditory Perception of Impulsiveness and Tonality in Vocal Fry
###### Abstract  
Vocal Fry is a voice quality that occurs in a healthy voice, but it can also be a sign of a voice disorder. In this study, we investigated the relationship between the parameters of voice production, a dedicated psychoacoustic feature, and the perceptual aspects of vocal Fry. Two perceptual experiments were carried out to determine whether the fundamental frequency, the open quotient, and the glottal area pulse skewness affect the perception of vocal Fry in synthetic vowels. Thirteen listeners participated in the perceptual experiments to assess the following attributes: binary Fry (yes/no) and impulsiveness, tonality, and naturalness (7-point Likert scales). The results suggest that the perception of vocal Fry is mainly triggered by a low fundamental frequency, but the open quotient also plays a role, with narrower glottal area pulses slightly increasing the probability of perceived fry. Perceived tonality is inversely related to perceived impulsiveness. Internal reference standards of listeners appear to have fixed elements but may also be affected by anchoring and the short-term (i.e., within-vowel) context of the stimuli. In addition, the prominence of the peaks observed in the loudness curve over time appears to be related to graduations of Fry. v 202  
all instances of vocal fry. Both creak and fry are also characterized in the literature by a constricted glottis [12; 13]. In addition, vocal fry may be considered to be contrasted with falsetto, which has a high fundamental frequency Fo and a large open quotient Qo [14; 15]. * [PERSON] et al. use the term creak to refer to several distinct voice types, one of which they term fry [16]. They characterize so-called prototypical creak by low vibration frequency, strong jitter, and a constricted glottis. The latter is characterized by a small peak glottal opening, a long closed phase, and a low flow rate. According to [PERSON] et al., fry shares all of its properties with prototypical creak, except for jitter, which is substantially smaller in fry. [PERSON] et al. listed double and triple pulsing as another type of creak, as well as pressed voice (i.e., non-low pitched creak). * [PERSON] and [PERSON] observed that the literature used the term vocal fry for voices with low vibration frequencies involving large variations, or double pulsing irrespective of pitch [17]. * [PERSON] and [PERSON] distinguished between creak and fry based on the within-vowel position. They stated that creak is a type of fry and is observed in of the end of a vowel [18]. With regard to auditory perception, vocal fry is reminiscent of a stick being run along a railing or the popping of corn, with temporal auditory segregation of individual acoustic pulses occurring [13; 19; 20]. A stick that is run along a railing results in quasi-periodic pulses, while the pulses associated with popping corn are random. Pauses between glottal pulses, i.e., sufficiently long time intervals of glottal inactivity, were observed to be necessary to enable auditory segregation. In particular, a decay of 42-44 dB SPL between pulses was reported as the threshold above which temporal auditory segregation of individual pulses occurs [21]. The current study defines vocal fry and the related parameters of voice production as follows. On the level of voice production, we focus on the definition of fry by [PERSON] et al., that is, low vibration frequencies, low jitter, and constricted glottis. The voice production parameters that we consider are the vibration frequency Fo, the open quotient Qo, and the pulse skewness Qs. The most relevant parameter is the vibration frequency of the vocal folds. The average vibration frequencies that have been reported for vocal fry range from 20 Hz to 70 Hz with a mean of 50 Hz [12]. The open quotient relates the duration of the open glottal phase to the duration of the cycle.