The perceptual Evaluation of the Voice in Morbid Obesity

Introduction

In humans and other animals, the voice is the primary means of communication. Voices transmit a variety of information, including physical characteristics such as body size and sex, as well as cues to the vocalizing individual's identity and emotional state. Dynamic changes in the physiological vocal production system produce vocalizations.

The respiratory system, laryngeal system, articulation, and nervous system are the four cardinal body systems involved in the production of speech in humans. The first three systems control the physical aspects of speech, while the nervous system regulates these systems on both the conscious and subconscious levels.^[1]

Voice is produced in 3 steps: 

The primary sound produced by vocal fold vibration is referred to as "voiced sound." This is also known as a "buzzy" sound. The voiced sound is then amplified and modified by the vocal tract resonators (throat, mouth cavity, and nasal passages), this process known as resonance. The resonators produce the person's distinct voice.  At last, the vocal tract articulators (the tongue, soft palate, and lips) alter the voiced sound, this process known as articulation. Words are produced by the articulators^[2].

Phonation must be coordinated with respiration. Phonation is a dynamic system. A low subglottal pressure is required for vocal fold vibration. This minimal subglottal pressure is known as the phonation threshold pressure (PTP)^[3].

PTP can be affected by the configuration of the glottal aperture and the viscoelasticity of the vocal folds. The tension and elasticity of vocal folds can be adjusted because they are shelf-like elastic protuberances of muscles and mucosa. They can be thinner, thicker, shorter or longer, open wide, close together, or come together in the central portion. They can also be raised or depressed in their vertical relationship to the cavities above.^[4]

Obesity is a major public health issue because it significantly increases the risk of diseases such as type 2 diabetes, fatty liver disease, hypertension, myocardial infarction, stroke, dementia, osteoarthritis, obstructive sleep apnea, and several cancers, contributing to a decline in both quality of life and life expectancy. Obesity is also linked to unemployment, social disadvantages, and lower socioeconomic productivity, posing an increasing economic burden^[5].

Obesity can cause changes in the three levels of voice production: the respiratory system (due to adipose tissue deposition in the thoracic and abdominal region), the vibratory system (due to increased vocal fold mass), and the resonator system (by deposition of fat on the circumference of the neck, altering the dimensions of the pharyngeal resonator channel) [6].

Aim of the study: to cast more light on the effect of obesity on voice in patients of morbid obesity.

Subjects and methods

The present study was occurred in Minia University hospital and general surgery private clinic on the duration of the period between January 2022 and September 2022  and included 50 subjects were diagnosed as morbid obese (BMI>40), their age between 20-55 years old. This study was approved by the Ethics Committee for Research in the Faculty of Medicine, Minia University (Approval No.209:2022), and consents were obtained from subjects.

Data entry and analysis were all done with I.B.M compatible computer using software called SPSS (Statistical Package for social science) for windows version 13. Graphics were done by Excel.

Quantitative data were presented by mean and standard deviation, while qualitative data were presented by frequency distribution.

For each subject, the parameters were collected before and after surgery, and the appropriate statistical analysis for small-size samples (Wilcoxon nonparametric paired test) was conducted. The analysis took into consideration the design (before and after) and modality of data collection (paired data)

P value was considered statistically significant (S) if < 0.05, highly significant (HS) if <0.001 and no significant (NS) if >0.05. Post Hoc test was used to differentiate between P values.

Patients were assessed according to voice assessment protocol in the Phoniatrics Unit, Minia University Hospital, as follow

I- Elementary Diagnostic Procedures:

  1- Subject interview and history taking including personal history(name, age, sex, residence, marital status, number of children, and their ages, education, occupation), complaint, clinical symptoms of the patient, as change of voice, throat pain, throat dryness, globus sensation, frequent throat clearing, chocking attacks .

Symptoms of reflux as burning sensation in your chest (heartburn), regurgitation of

food or sour liquid, upper abdominal or chest pain ,trouble swallowing (dysphagia), sensation of a lump in your throat.

 2- Auditory perceptual assessment "APA": each voice sample was recorded for approximately 5 seconds while sustaining the vowel [a:] for three times and reading the "walk paragraph" at a comfort-table pitch and loudness. Acoustic analysis was performed on the stable central 3 seconds of a sustained vowel and the "walk paragraph." We used the "Grade" factor in the GRBAS scale to rate overall severity in this study.

1. II) Clinical Diagnostic Aids:

a- BMI > 40 [BMI= weight in kg \ (height in meters) ²].

b- Neck circumference (in cm) was measured in the midway of the neck, between mid-cervical spine and mid anterior neck, to within 1 mm, using non-stretchable plastic tape with the subjects standing upright. In men with a laryngeal prominence (Adam's apple), it was measured just below the prominence. While taking this reading, the subject was asked to look straight ahead, with shoulders down, but not hunched. Care was taken not to involve the shoulder/neck muscles (trapezius) in the measurement.

Discussion

Normal voice characteristics include adequate loudness for the environment, pitch appropriate for age and gender, pleasant quality, free of random noise,

flexibility with variations in emphasis, and significance. Dysphonia is a symptom defined as "difficulty emitting voice with its natural characteristics"^[7].

Obesity is a health issue that affects many body systems, including respiration and voice. The air exhaled from the lungs is modulated in the vocal fold and is modified in resonating cavities such as the pharynx, oral, and nasal cavities, as well as by structures such as the lips, tongue, and palate^[7].

Obesity and voice are linked because of the influence of excess body weight on abdominal breath support for voice production. Obesity can impair resonance in severe cases due to a significantly reduced pharyngeal lumen^[8].

We observed that study group had phonasthenic symptoms. In Study group, 33 (67.7%) of morbid obese patients had phonasthenia, and 17 (32.3%) of morbid obese patients didn't have phonasthenia. This may be explained by that improvement of phonasthenia after decrease BMI by bariatric surgery due to improvement of vocal fold vibration after improvement of respiration due to weight loss. As restriction of diaphragm movement by fat deposition which lead to decrease respiratory volume and impaired phonation with decrease of MPT. All of these previous factors made patient use more effort to produce sustained phonation and expressed this in form of vocal fatigue. So, after weight loss all these factors decreased and lead to improvement of phonasthenia. And this result agree with^[9] who reported that 21 women with morbid obesity were aged between 28 and 68 years with an average age of 41.33 (±11.26) years. Of these, 14 (66.6%) suffered from vocal complaints before the operation. Among the volunteers that reported vocal complaints, 10 described having vocal fatigue (71%), eight described voice failure (57.14%), seven vocal effort (50%) and six drying of the vocal tract (42.8%). After surgery none of the women reported vocal complaints.

We also observed that group study had high neck circumference (NC). In G, the mean of neck circumference (NC) was 40.5±1.9. Neck circumference is indicated as a predictor for body weight, excess fat in the upper region of body cause increase of neck circumference. This agree de ^[10] who reported that measurement of NC can be used to define obesity and that excess fat and muscle can overwhelm the respiratory system.

We observed that patients of group study had reflux symptoms. In G, 53.3% of patients had reflux symptoms. This result may be explained by the fact that in overweight and obese patients, extrinsic gastric compression from increased visceral adiposity may result in increased intragastric pressure and thus a favorable pressure gradient for reflux to occur. And  this result agree with^[11].

Discussion

Normal voice characteristics include adequate loudness for the environment, pitch appropriate for age and gender, pleasant quality, free of random noise, flexibility with variations in emphasis, and significance. Dysphonia is a symptom defined as "difficulty emitting voice with its natural characteristics"[7].

  Obesity is a health issue that affects many body systems, including respiration and voice. The air exhaled from the lungs is modulated in the vocal fold and is modified in resonating cavities such as the pharynx, oral, and nasal cavities, as well as by structures such as the lips, tongue, and palate [7].

Obesity and voice are linked because of the influence of excess body weight on abdominal breath support for voice production. Obesity can impair resonance in severe cases due to a significantly reduced pharyngeal lumen [8].

   We observed that the study group had phonasthenic symptoms. In the study group, 33 (67.7%) of morbidly obese patients had phonasthenia, and 17 (32.3%) of morbidly obese patients didn't have phonasthenia. This may be explained by the restriction of diaphragm movement by fat deposition, which leads to decreased respiratory volume and impaired phonation with a decrease in MPT. All of these previous factors made patients put in more effort to produce sustained phonation and expressed this in the form of vocal fatigue. So after weight loss, all these factors decreased and led to an improvement in phonasthenia. And this result agree with [9] who reported that 21 women with morbid obesity were aged between 28 and 68 years, with an average age of 41.33 (±11.26) years. Of these, 14 (66.6%) suffered from vocal complaints before the operation. Among the volunteers that reported vocal complaints, 10 described having vocal fatigue (71%), eight described voice failure (57.14%), seven described vocal effort (50%), and six described drying of the vocal tract (42.8%). After surgery, none of the women reported vocal complaints.

We also observed that the group studied had a high neck circumference (NC). In G, the mean neck circumference (NC) was 40.5±1.9. Neck circumference is indicated as a predictor for body weight; excess fat in the upper region of the body causes an increase in neck circumference.

This agree de [10] who reported that measurement of NC can be used to define obesity and that excess fat and muscle can overwhelm the respiratory system.

We observed that patients in the group study had reflux symptoms. In G, 53.3% of patients had reflux symptoms. This result may be explained by the fact that in overweight and obese patients, extrinsic gastric compression from increased visceral adiposity may result in increased intragastric pressure and thus a favorable pressure gradient for reflux to occur. And this result agrees with [11].