Voice disorders

In short

A voice disorder exists when the quality, pitch, loudness or endurance of the voice differs from what is expected for a speaker's age, sex, culture and vocal demands, or when the speaker experiences discomfort and limitation in using the voice. It arises from structural, neurological or behavioural changes in the larynx, the breath supply or the resonating tract, and it is assessed multidimensionally - perceptually, visually, acoustically, aerodynamically and by patient self-report. This is core content in BASLP clinical papers on "Voice and its disorders", in AIISH/university viva and clinical practicals, and in RCI-linked licensing and CRE work. Speech-language pathologists apply it daily in ENT and voice clinics, head-and-neck cancer rehabilitation, and with occupational voice users - teachers, call-centre agents, singers, lawyers and playback artists.

Explained

The normal voice and how phonation works

• Three subsystems: respiration (power supply), phonation (vocal folds as the sound source), resonance (pharynx, oral and nasal cavities as the filter) - the source-filter theory.
• Myoelastic-aerodynamic theory (van den Berg): subglottal pressure blows the adducted folds apart; the Bernoulli effect plus tissue elasticity pulls them back together, producing self-sustained oscillation.
• Body-cover model (Hirano): epithelium and superficial lamina propria (Reinke's space) form the pliable cover; vocal ligament and thyroarytenoid muscle form the body. Mucosal wave depends on a healthy cover - its loss signals scar, sulcus or malignancy.
• Intrinsic muscles: thyroarytenoid and lateral cricoarytenoid (adduct), interarytenoid (closes posterior glottis), posterior cricoarytenoid (the only abductor), cricothyroid (lengthens and tenses the folds - raises pitch).
• Innervation: recurrent laryngeal nerve (all intrinsic muscles except cricothyroid) and external branch of the superior laryngeal nerve (cricothyroid), both from the vagus (CN X).
• Normal values (approximate; vary with language and study): habitual F0 about 110-130 Hz in adult Indian males, 200-220 Hz in females, 250-300 Hz in young children; conversational intensity 60-70 dB SPL at 30 cm.

Classification of voice disorders

1. Organic - structural (mass or tissue change):
   • Vocal nodules: bilateral, symmetrical, at the midpoint of the membranous fold (junction of anterior one-third and posterior two-thirds) - from phonotrauma; commonest in children and teachers.
   • Polyp: usually unilateral, pedunculated or sessile; often after a single traumatic episode or with smoking.
   • Cyst (mucous retention or epidermoid) in the superficial lamina propria - poor response to therapy, usually surgical.
   • Reinke's oedema (polypoid degeneration): diffuse oedema of the superficial lamina propria, strongly linked to smoking; abnormally low pitch in women.
   • Contact ulcer / vocal process granuloma: posterior third, from hard glottal attack, reflux or intubation.
   • Recurrent respiratory papillomatosis: HPV 6/11; the commonest neoplasm of the paediatric larynx; needs repeated debulking.
   • Laryngeal carcinoma: persistent hoarseness beyond 2-3 weeks in an adult smoker is a red flag for urgent ENT referral.
   • Sulcus vocalis, vocal fold scar, laryngeal web, laryngomalacia; presbyphonia (age-related atrophy and bowing).
2. Organic - neurogenic:
   • Unilateral vocal fold paralysis (RLN): breathy, weak voice, diplophonia, short MPT; fold in paramedian position. Common after thyroidectomy, cardiac or oesophageal surgery, or from a mediastinal lesion.
   • Bilateral paralysis: voice may be adequate but airway compromised - stridor; tracheostomy may be needed.
   • Superior laryngeal nerve palsy: loss of pitch range and vocal fatigue, flaccid fold with lower pitch.
   • Spasmodic dysphonia: a focal laryngeal dystonia - adductor type gives a strained-strangled voice with breaks on vowels (commonest); abductor type gives breathy breaks on voiceless consonants; mixed type combines both.
   • Essential vocal tremor (4-7 Hz rhythmic modulation); vocal fold paresis; hypokinetic voice of Parkinson's disease (reduced loudness, monopitch, breathiness).
3. Functional / behavioural:
   • Muscle tension dysphonia (MTD): primary (no lesion) or secondary (compensating for a lesion); supraglottic constriction, high larynx, anteroposterior squeeze; hallmark is pain on palpation of the thyrohyoid space.
   • Vocal fatigue, vocal abuse/misuse, ventricular (plica ventricularis) phonation, diplophonia.
   • Puberphonia (mutational falsetto): persistence of a high-pitched pre-pubertal voice in a post-pubertal male with a normal larynx - frequently seen in Indian clinics and highly responsive to therapy.
   • Psychogenic / conversion aphonia or dysphonia: whisper or aphonia with a normal cough and normal vegetative phonation.
4. Laryngopharyngeal reflux (LPR) as a contributor: morning hoarseness, globus, throat clearing, posterior laryngitis - managed medically plus behavioural change.
5. Resonance disorders overlap voice: hypernasality, hyponasality, cul-de-sac resonance (detailed under cleft palate/resonance teaching).
6. Alaryngeal voice: after total laryngectomy.

Assessment - the multidimensional protocol

• Case history: onset and course, vocal load (hours of speaking, classroom or phone use), hydration, smoking, tobacco/gutka, alcohol, spices and reflux symptoms, allergies, singing training, surgery, intubation, occupation and medication (inhaled steroids, antihistaminics, diuretics).
• Perceptual rating - GRBAS (Hirano): Grade, Roughness, Breathiness, Asthenia, Strain; each 0 (normal) to 3 (severe). Extended GRBASI adds instability.
• CAPE-V (ASHA): 100 mm visual analogue lines for overall severity, roughness, breathiness, strain, pitch and loudness, using sustained vowels, six standard sentences and running speech.
• Self-report: VHI (30 items, functional/physical/emotional, 0-4 each, total 0-120), VHI-10 (0-40), V-RQOL, Voice Symptom Scale, Singing VHI; Indian-language translated and validated versions exist for Hindi, Kannada, Tamil, Telugu, Malayalam and Marathi (check validation before clinical use).
• Visual examination (by/with ENT): indirect laryngoscopy, flexible nasolaryngoscopy (best for connected speech), rigid 70°/90° telescopy (best image), videostroboscopy for mucosal wave, amplitude, glottal closure, symmetry, periodicity; high-speed videoendoscopy and electroglottography (EGG) for contact quotient in research and advanced clinics.
• Acoustic analysis (Praat is free and widely used; MDVP, Dr Speech, VAGHMI also used in India): F0 and its SD, jitter, shimmer, HNR/NHR, CPPS (cepstral peak prominence smoothed) and AVQI for severity in connected speech, voice onset/offset, Voice Range Profile (phonetogram) mapping F0 against intensity.
• Aerodynamic measures: MPT, s/z ratio, mean airflow rate, phonation quotient, subglottal pressure (intra-oral pressure during /pa/ repetition), laryngeal airway resistance, phonation threshold pressure - measured with a Phonatory Aerodynamic System, pneumotachograph or a simple water manometer.
• Deciding the diagnosis requires all strands: therapy must never start on an unseen larynx - visualisation is mandatory before behavioural voice therapy.

Management - behavioural, medical and surgical

• Indirect therapy / vocal hygiene: hydration (systemic water and steam inhalation), reduce throat clearing and shouting, no whispering, voice rest that is relative not total, avoid tobacco and smoke, control reflux (meal timing, head-end elevation), amplification for teachers, manage vocal load with scheduled voice breaks.
• Direct facilitating techniques: yawn-sigh, chant talk, chewing (Froeschels), confidential/easy voice, glottal fry, pitch and loudness alteration, digital manipulation, respiration training, relaxation, biofeedback, auditory masking (Lombard), inhalation phonation.
• Physiological / holistic programmes:
  • Vocal Function Exercises (Stemple): warm-up, stretch (glide up), contract (glide down), power (sustained /ol/ on musical notes) - twice daily, two repetitions.
  • Resonant Voice Therapy (Lessac-Madsen): forward oral vibratory sensations on nasals, barely abducted-to-barely adducted posture.
  • Semi-occluded vocal tract (SOVT) exercises: straw phonation, lip/tongue trills, humming, water-resistance therapy - raise supraglottic pressure, lower phonation threshold pressure and impact stress.
  • Accent Method: abdominal breathing with rhythmic accented phonation.
  • Manual circumlaryngeal therapy (Aronson) and laryngeal massage for MTD; Casper-Stone confidential voice for acute phonotrauma.
  • LSVT LOUD for hypokinetic dysarthrophonia in Parkinson's disease - intensive, 16 sessions in 4 weeks, "think loud, think shout", high effort and calibration.
• Puberphonia: Gutzmann's digital pressure on the thyroid prominence, cough-to-phonation, hard glottal attack, masking, laryngeal lowering - usually normalised in a few sessions; relapse prevention and counselling matter.
• Conversion aphonia: elicit true phonation from cough, throat clear or hum, shape it into speech in one or two sessions, with counselling and psychiatric referral where indicated.
• Medical: anti-reflux measures, allergy and sinus treatment, voice-sparing drug review, botulinum toxin A injection into the thyroarytenoid (adductor spasmodic dysphonia; effect lasts about 3-4 months).
• Phonosurgery: microlaryngoscopic excision of polyp/cyst/papilloma with mucosa-sparing technique; injection laryngoplasty (hyaluronic acid, fat, calcium hydroxylapatite) and type I medialisation thyroplasty / arytenoid adduction for unilateral paralysis; nerve reinnervation; type III thyroplasty to lower pitch and cricothyroid approximation / type IV to raise it (also used in gender-affirming voice care); cordotomy or arytenoidectomy for bilateral paralysis.
• Sequencing rule: behavioural therapy first for nodules, MTD and functional disorders; surgery first for cysts, large polyps, papilloma and malignancy, always followed by post-operative voice therapy.

Alaryngeal voice rehabilitation after total laryngectomy

• Pre-operative counselling on loss of voice, permanent tracheostoma, altered smell, taste and lifting, plus options for communication.
• Oesophageal speech: air is injected (glossopharyngeal press) or inhaled into the oesophagus and released to vibrate the pharyngo-oesophageal segment; typical F0 about 60-80 Hz (much lower than a laryngeal voice), 3-8 words per air charge; no device cost but needs long training.
• Tracheo-oesophageal puncture (TEP) with a voice prosthesis (Provox, Blom-Singer and Indian-made low-cost prostheses): pulmonary air drives the PE segment - the most fluent and loudest option; needs stoma occlusion or a hands-free valve, prosthesis care and periodic replacement.
• Electrolarynx: neck- or intra-oral type; immediate and reliable, mechanical quality; useful when TEP and oesophageal speech fail or are delayed.
• Adjuncts: heat-and-moisture exchanger for the stoma, stoma hygiene, pharyngo-oesophageal spasm management (myotomy or Botox), counselling and support groups.

Indian practice, law and service context

• Rehabilitation Council of India Act, 1992: only an RCI-registered professional (CRR number) may practise speech-language pathology; registration needs periodic renewal through Continuing Rehabilitation Education (CRE) credits - check current RCI norms as they are revised.
• Rights of Persons with Disabilities Act, 2016 lists "speech and language disability" among the specified disabilities, with 40% as benchmark disability; certification follows the Gazette guidelines for assessment of speech and language disability, which use voice/speech and language parameters. Certification is done by notified medical boards, usually with ENT and SLP inputs.
• Institutes and services: AIISH Mysuru, AYJNISHD (D) Mumbai, NIEPMD Chennai, NISH Thiruvananthapuram, AIIMS, PGIMER, CMC Vellore, JIPMER and large private hospital voice clinics; DEIC and district rehabilitation centres under the National Health Mission; CGHS/ESIC and PMJAY packages may cover laryngectomy and voice prosthesis - verify the current package list.
• Cost reality: a voice prosthesis typically costs a few thousand to about ₹20,000-40,000 depending on type and brand, and is a recurring expense; an electrolarynx and Praat-based acoustic analysis are the economical options in resource-limited settings. Teletherapy for voice is now routine, subject to the telemedicine practice guidelines.

Key points

• Dysphonia - any disorder of voice quality, pitch, loudness or endurance; aphonia - complete loss of voice.
• Phonotrauma - the preferred term for abuse/misuse-induced lesions such as nodules and polyps.
• Nodules - bilateral, mid-membranous, usually respond to voice therapy; cyst - unilateral, submucosal, usually surgical.
• Reinke's oedema - smoking-related, pathologically low pitch; contact granuloma - posterior glottis, reflux and intubation.
• Only abductor of the vocal folds is the posterior cricoarytenoid; the cricothyroid controls pitch via the superior laryngeal nerve.
• Unilateral RLN palsy - breathy voice, incomplete glottal closure, short MPT, high phonation quotient.
• Adductor spasmodic dysphonia - strained voice breaks on voiced segments; treated with botulinum toxin, not voice rest.
• MTD - normal folds with supraglottic constriction and laryngeal tenderness; treated with circumlaryngeal massage and SOVT.
• Puberphonia - high-pitched male voice with a normal larynx; digital pressure and cough-phonation usually resolve it quickly.
• GRBAS - 0-3 perceptual scale on five parameters; CAPE-V - 100 mm visual analogue scale.
• VHI - 30 items, maximum 120; VHI-10 maximum 40 - a disability/handicap measure, not an impairment measure.
• MPT - about 25-35 s (adult men), 15-25 s (women), ~10 s in children; shortened in glottal incompetence.
• s/z ratio above about 1.4 suggests laryngeal pathology with intact respiration.
• Jitter - cycle-to-cycle frequency perturbation (hoarseness/roughness); shimmer - amplitude perturbation; HNR - harmonic energy relative to noise energy, so it falls with added noise (breathiness); NHR is the inverse.
• Videostroboscopy - the clinical standard for mucosal wave and glottal closure; absent mucosal wave suggests scar, sulcus or invasion.
• CPPS and AVQI - cepstral/multiparametric measures valid for connected speech and severe dysphonia, where jitter and shimmer become unreliable.
• TEP with voice prosthesis - most fluent post-laryngectomy voice; oesophageal speech has no device cost; electrolarynx is the fastest to start.
• Hoarseness beyond 2-3 weeks in an adult, especially a tobacco user, requires laryngeal visualisation before any therapy.

Formulas and examples

Example 1 - s/z ratio and its interpretation. A 32-year-old teacher sustains /s/ for 15.0 s and /z/ for 9.0 s.

• s/z = 15.0 ÷ 9.0 = 1.67.
• Above 1.4, with normal /s/ duration, so respiratory support is adequate but voicing is not sustained → suspect a mass lesion or glottal incompetence; refer for laryngoscopy.

Example 2 - phonation quotient after thyroidectomy. Vital capacity 4,000 mL; MPT on /a/ = 8 s.

• PQ = 4,000 ÷ 8 = 500 mL/s, far above the 120-190 mL/s range.
• Air is escaping through an incompletely closing glottis - consistent with unilateral vocal fold paralysis; management options are injection laryngoplasty or medialisation plus voice therapy.

Example 3 - computing jitter from measured periods. Five successive periods: 5.00, 5.10, 4.95, 5.05, 5.00 ms.

• Mean period = (5.00+5.10+4.95+5.05+5.00)/5 = 25.10/5 = 5.02 ms → F0 = 1/0.00502 s ≈ 199 Hz.
• Absolute differences: 0.10, 0.15, 0.10, 0.05 ms; sum = 0.40; mean = 0.40/4 = 0.10 ms (= jitter absolute 100 µs).
• Jitter % = (0.10 ÷ 5.02) × 100 = 1.99% - about twice the 1.04% norm, consistent with perceptual roughness.

Example 4 - DSI calculation. A patient with vocal nodules: MPT = 15 s, highest F0 = 600 Hz, softest intensity = 55 dB, jitter = 0.30%.

• 0.13 × 15 = 1.95; 0.0053 × 600 = 3.18; −0.26 × 55 = −14.30; −1.18 × 0.30 = −0.354; constant +12.4.
• DSI = 1.95 + 3.18 − 14.30 − 0.354 + 12.4 = +2.88 - mild dysphonia (normal ≈ +5). After eight weeks of therapy MPT 22 s, F0-high 750 Hz, I-low 48 dB, jitter 0.18% → 2.86 + 3.975 − 12.48 − 0.212 + 12.4 = +6.54, i.e. a clear improvement.

Example 5 - laryngeal resistance and pitch range. Ps measured from /pa/ repetitions = 8 cm H₂O; mean flow = 0.15 L/s. Lowest F0 = 100 Hz, highest = 400 Hz.

• R = 8 ÷ 0.15 = 53.3 cm H₂O/L/s - at the upper end/slightly raised, as expected in muscle tension dysphonia.
• Range = 39.86 × log₁₀(400/100) = 39.86 × 0.6021 = 24.0 semitones = 2 octaves.

Where it is used

• Hospital voice clinics and ENT departments (AIIMS, PGIMER, CMC Vellore, JIPMER, Apollo, Fortis, Manipal): joint SLP-laryngologist clinics running stroboscopy, acoustic and aerodynamic assessment and therapy.
• Head-and-neck oncology and laryngectomy rehabilitation: Tata Memorial Centre and regional cancer centres - pre-operative counselling, TEP prosthesis fitting and care, oesophageal speech training, electrolarynx trials.
• Occupational and professional voice: teachers under school health programmes, call-centre and BPO agents, singers, playback artists, theatre performers, trainers, politicians and priests - screening, amplification advice and vocal load management.
• Paediatric and school services: DEICs, special schools and district rehabilitation centres - childhood nodules, papillomatosis follow-up, voice in hearing impairment.
• Job roles: clinical SLP/audiologist (RCI-registered), voice therapist in private voice studios, lecturer in BASLP colleges, clinical researcher, product and application specialist for stroboscopy, PAS and acoustic analysis systems, teleconsultation SLP.
• Instrumentation and software: Praat (free), MDVP/CSL, Dr Speech, VAGHMI, Phonatory Aerodynamic System, EGG, flexible and rigid endoscopes with stroboscopes - used in both clinical and research settings.

Interview questions

• Q: State the myoelastic-aerodynamic theory of phonation in one line. A: Subglottal air pressure separates the adducted vocal folds, and tissue elasticity plus the Bernoulli effect brings them back together, producing sustained oscillation without any neural firing per cycle.
• Q: How do you distinguish primary muscle tension dysphonia from a mass lesion? A: MTD shows normal fold structure with supraglottic constriction, a raised and tender larynx, and symptoms fluctuating with vocal load, whereas a lesion shows a visible mass with a localised disturbance of the mucosal wave on stroboscopy.
• Q: Why is whispering discouraged in voice rest? A: True whisper often involves anterior-posterior supraglottic constriction and high laryngeal effort with poor vocal fold vibration, so it can aggravate strain; confidential easy voice is advised instead.
• Q: What does an s/z ratio of 2.0 tell you? A: Respiratory support is adequate but voicing cannot be maintained, suggesting a laryngeal problem - a mass lesion or incomplete glottal closure - needing visualisation.
• Q: Which single muscle abducts the vocal folds, and what happens if both are paralysed? A: The posterior cricoarytenoid; bilateral paralysis leaves the folds near midline, so voice may be fair but the airway is critically narrowed, causing stridor.
• Q: Why are jitter and shimmer unreliable in severe dysphonia? A: They require accurate cycle-by-cycle period extraction, which fails in aperiodic or aphonic signals; cepstral measures such as CPPS or multiparametric indices like AVQI are used instead.
• Q: Give the DSI formula and interpret a value of −2. A: DSI = 0.13 MPT + 0.0053 F0-high − 0.26 I-low − 1.18 jitter% + 12.4; −2 indicates moderate dysphonia, since +5 is a normal voice and −5 severe.
• Q: A 17-year-old boy has a childlike high-pitched voice and a normal larynx. Diagnosis and management? A: Puberphonia (mutational falsetto); Gutzmann's digital pressure on the thyroid prominence, cough-to-phonation, masking and laryngeal lowering, with carryover practice and counselling - usually resolved in a few sessions.
• Q: Which voice disorder is treated primarily with botulinum toxin and why? A: Adductor spasmodic dysphonia - a focal laryngeal dystonia; small doses into the thyroarytenoid reduce spasms for about three to four months, with therapy to optimise the resulting voice.
• Q: Compare TEP voice with oesophageal speech. A: TEP voice uses pulmonary air through a prosthesis and gives longer phrases, higher intensity and faster learning, but needs a surgical puncture, prosthesis maintenance and recurring cost; oesophageal speech is device-free and free of cost but is slower, quieter and harder to learn.
• Q: Name the key behavioural programmes in physiological voice therapy. A: Vocal Function Exercises, Resonant Voice Therapy, Accent Method, SOVT/straw phonation, confidential voice and LSVT LOUD for hypokinetic dysphonia.
• Q: Which law governs your right to practise voice therapy in India, and what does the RPwD Act add? A: The Rehabilitation Council of India Act, 1992 requires registration (CRR) with CRE-based renewal; the RPwD Act, 2016 lists speech and language disability as a specified disability with a 40% benchmark, assessed and certified by notified boards.

Common mistakes

• Starting voice therapy without laryngeal visualisation, or dismissing persistent hoarseness in a tobacco user instead of referring for urgent ENT review.
• Confusing nodules with polyps and cysts - bilateral and mid-membranous versus usually unilateral, and which are surgical first.
• Treating VHI as a measure of impairment; it quantifies the patient's perceived handicap and can be low in severe pathology or high in mild dysphonia.
• Prescribing total voice rest for weeks, or whispering, rather than relative rest with a confidential easy voice.
• Reporting jitter and shimmer on a severely aperiodic or aphonic sample, or comparing values across different software and norms.
• Mixing units in aerodynamic work - mL/s with L/s for flow, or cm H₂O with kPa for pressure - which distorts resistance values by orders of magnitude.
• Omitting carryover, relapse prevention and vocal-load counselling for occupational voice users, so the lesion returns after discharge.

Related topics

• Laryngeal anatomy and physiology of phonation · Adult neurogenic communication disorders: aphasia, dysarthria and apraxia · Head and neck cancer and laryngectomy rehabilitation · Resonance disorders and cleft palate speech · Acoustic and aerodynamic analysis of speech · Professional voice care and vocal hygiene.