# Using a Lossy Electrical Transmission Line Model for Optimizing Straw Phonation Configurations
## 4 Discussion
Third and finally, water resistance therapy is similar in intent to straw phonation by providing extra resistance to the patient, along with introducing nonlinear feedback to massage the vocal folds [28; 29; 30]. Along with the extension of the vocal tract with the aid of a straw, the end of the straw is submerged in water, requiring the phonation to push air through the water to produce bubbles. This submerged portion would have an altered inductance due to the mass of the water being moved, but also capacitance due to the incompressibility of the water. More research into electrical analogs for these effects could be very valuable for improving patient outcomes. Besides the vocal tract, the larger scheme of sound production and reception could be incorporated into the transmission line model. The human ear transmits auditory information from the tympan membrane to the cochlea where the signal is converted to electrical nerve impulses [31], so the ear can also be modeled as a transmission line [32; 33]. By matching the impedance of the source and the load, the entire phonation process could be optimized to ensure that the vocal quality produced from speaking can be correctly received. Previous research by [PERSON] [34; 35] has shown that phonation threshold pressure (PTP) is proportional to F0. Thus, a valuable mechanism for straw phonation to ease phonation is to reduce the fundamental frequency meaning that phonemes which already have a high impedance F0 present possibly the best opportunity for straw phonation. If straws can reduce F0 for these sounds, then PTP could be significantly lowered while still maintaining a high impedance level useful for other theories of straw phonation. Alternatively, an explanation for the benefits of straw phonation is the ability for patients to more easily achieve phonation and thus gain the sensory information of resonance with less exertion. Phonation involves complex neuro-muscular interactions which reinforce each other based on the sensory experience of producing sound. Since relatively little research has been done on the lasting effect of straw phonation after the patient stops using the straw [36], an advantageous configuration for straw phonation could maximize impedance while keeping the fundamental frequency of resonance as close to that without the straw as possible. In this way, the acoustic-mechanical interaction of the vocal tract and glottis has maximum potential to reduce PTP while the patient is able to experience the sensory information of phonating at that specific frequency, as would be required without a straw. Given that this theory contradicts the work by [PERSON] about the relationship between F0 and PTP, more research is needed to explain the underlying mechanism of straw phonation. Moreover, future research in multi-step straw phonation, where the straw is slowly reduced in size until the straw is entirely removed, may be worthwhile in order to train the participant to phonate effectively without the straw. This is in line with the ultimate goal of straw phonation which is the increase vocal quality and reduce phonation effort of speech after the therapy. Conceptualization, J.R. and N.H.; methodology, J.R.; software, J.R.; validation, J.R.; formal analysis, J.R.; investigation, J.R.; resources, J.R.; data curation, J.R.; writing--original draft preparation, J.R.; writing--review and editing, J.R., N.H., M.S., A.S. and J.J.; visualization, J.R.; supervision, M.S., A.S. and J.J.; project administration, J.J.; funding acquisition, J.J. All authors have read and agreed to the published version of the manuscript. This research and APC were funded by National Institutes of Health grant number 5R01 DC015906 from the National Institute on Dearness and other Communicative Disorders. Not applicable. The authors declare no conflicts of interest.