Halachic Talking Part I

A. Background

Production of sound by biological species requires phonation, the production of primary vocal tones by the vocal folds. Arytenoids, pyramidal shaped cartilages on the upper border of the cricoid cartilage, serve as the attachment sites for some of the intrinsic muscles of the larynx which allows for the complex movement and fine adjustments of the vocal folds. The vocal folds are split into the true and false vocal folds. The false vocal folds are above the true vocal folds and are separated from them by the laryngeal ventricle that contains mucus producing glands that provide lubrication for the true vocal folds. The true vocal fold is involved in phonation. The intrinsic muscles of the vocal fold are responsible for movement of the vocal folds and subtle tension adjustments. Phonation is the result of the interaction of the aerodynamic forces of exhaled air from the lungs with the viscoelastic properties of the true vocal fold mucosa which causes vibratory oscillating waves. The frequency of those vibrations—pitch—is determined by vocal fold length and tension and is regulated by the cricothyroid muscle. The vocal tones are then modified by resonation in the pharynx and nose which add harmonics and timbre followed by articulation by the fine motor control of the tongue, palate and lips. Pathology affecting the cartilage, muscles, lubrication or the nerves can all affect the ability or quality of the sound[1].

In a simple sentence, the biological mechanism of producing sound involves using air to create sound waves through vibration and resonation. Microphones function differently as they convert sound waves into electrical current that can then be transmitted to a speaker producing sound waves[2]. Similarly, hearing aids are composed of a microphone that receives sound and converts it into a digital signal, an amplifier that increases the strength of the signal and a speaker in the ear to produce the sound[3]. People suffering from hearing loss due to damage of the hair cells in the ear experience improved hearing with the greater amplification of the sound waves in their ears.  Analog hearing aid convert sound waves into electrical signals and then amplify them. Digital hearing aids analyze the sound wave’s pitch and loudness in order to adjust to the listening environment. Both devices function in a similar fashion to yelling in the ear of someone who is hard of hearing. Increasing the sound waves allow them to compensate for loss of hair cells. Importantly, even patients that suffer only from unilateral hearing loss benefit from bilateral hearing aids so the sound heard by both ears is similar[4]. There are newer devices that transmit sound waves into vibrations, in effect replacing the function of the hair cells, that will be discussed in the next chapter along with cochlear implants.

            The above describe the biological and digital creation of sound, however, the definition of human sound in halacha needs to be precisely defined to understand the application of microphones, hearing aids and telephones in halacha. As demonstrated, these devices all function similarly and therefore sources regarding one can be applied to all. From the many available sources emerges two schools of thoughts, one that considers sound strictly biologically and the other that considers it more broadly.

[1] Bruch J.M. and Kamani D.V., Hoarseness in Adults, https://www.uptodate.com/contents/hoarseness-in-adults?search=vocal%20fold%20paralysis&source=search_result&selectedTitle=1~85&usage_type=default&display_rank=1, 2021.

[2] http://artsites.ucsc.edu/EMS/Music/tech_background/TE-20/teces_20.html

[3] https://www.nidcd.nih.gov/health/hearing-aids

[4] Weber P.C., Hearing Amplification in Adults. https://www.uptodate.com/contents/hearing-amplification-in-adults?search=hearing%20aids&source=search_result&selectedTitle=1~71&usage_type=default&display_rank=1#H3029744140 ,2021