In order to carry out robust assessments of the human voice that are useful for diagnosing potential voice disorders, providing baseline data against which therapeutic progress can be assessed, the collection of data for research purposes, and similar, it is advisable to follow an assessment protocol. A protocol is a detailed, often standardized, procedure with clear guidelines regarding the exact method(s) of how to conduct a particular assessment. It sets out what data should be collected, under what conditions, exactly how they should be collected and by whom. Protocols attempt to reach agreement and uniformity concerning methods of voice assessment.

There are four main procedures for assessing the human voice for potential voice disorders:

1. case history
2. perceptual assessment
3. instrumental measurement
4. laryngoscopic examination

The case history

The information routinely collected in a case history will vary from institution to institution. However, a typical data collection is as follows.

OTOLARYGOLOGY (Ear, Nose and Throat) FINDINGS

e.g.  vocal fold palsy, granuloma, glottic chink, hearing

MEDICAL HISTORY (including current medications)

e.g. upper respiratory tract infections, allergies, nasal drip

PSYCHOLOGICAL HISTORY

e.g. depression, anxiety, panic attacks

SUBJECTIVE/PATIENT REPORTING

• Symptoms, e.g. soreness, vocal fatigue, dryness
• Variability, e.g. consistent, worse in morning, worse after being at work
• Vocal Hygiene, e.g. alcohol intake, caffeine intake
• Vocal Abuse, e.g. throat clearing, yelling
• Environmental Issues, e.g. noise, smoke, chemicals
• Effects on Lifestyle: e.g. social interaction, employment, confidence

Data in this category may also be gathered using self-completed questionnaires. These typically investigate the client’s own perceptions (or primary caregiver’s perceptions in the case of a young child) of the extent to which their presenting voice difficulty is interfering with their daily living routine; how it affects their quality of life; their perceptions of the type and severity of symptoms, and similar. Example questionnaires include: Voice Symptoms Scale [VoiSS] (Deary et al, 2003), Voice Handicap Index [VHI] (Jacobson et al, 1997), and the Pediatric Voice Handicap Index [pVHI] (Zur et al).

Perceptual assessment

The perceptual assessment of voice involves describing a person’s voice only by listening to it.

There are several published protocols to assist perceptual assessment. One such protocol is the GRBAS Scale (Hirano, 1981) which targets only voice quality: describing it in terms of Roughness, Breathiness, Asthenia (voice weakness), Strain and the overall Grade of the quality. A more encompassing protocol is the Vocal Profile Analysis protocol (Laver et al., 1981), which examines such things as vocal tract muscle tension, mandibular features as well as phonation type. Despite these protocols having been published several decades ago, they are still in use today in many clinics around the world. That said, as perceptual assessment relies heavily on the clinician’s own training in listening skills, clinicians often devise their own protocols, frequently adopting an eclectic approach that draws on areas of assessment cited in several published assessments. However, this must not be interpreted as being an unprincipled approach: all clinicians will adopt methods that systematically assess/measure relevant vocal parameters.

Instrumental measurement

The instrumental measurement of voice seeks to make quantifiable and objective measurements of vocal characteristics.

Several means of obtaining data may be used, e.g. vocal tract imaging, electromyography, electroglottography, acoustic analysis (such as Boersma’s (2020) Praat program). Acoustic analysis frequently assesses Maximum Phonation Time (MPT) and the S/Z Ratio.

Laryngoscopic examination

There are four main methods of laryngoscopic examination for investigating the larynx and vocal tract:

1. mirror laryngoscopy
2. rigid endoscopy
3. flexible nasendoscopy
4. direct laryngoscopy

References

Boersma, Paul & Weenink, David (2020). Praat: doing phonetics by computer [Computer program]. Version 6.1.09, retrieved 13 February 2020 from http://www.praat.org/.

Deary, I. J., Wilson, J.A., Carding, P.N. and MacKenzie K. (2003) ‘VoiSS: a patient-derived Voice Symptom Scale.’ J Psychosom Res 54(5): 483-489.

Hirano, M. (1981) Clinical Examination of Voice New York: Springer-Verlag.

Jacobson, B.H., Johnson A., Grywalski C., Silbergleit A., Jacobson G. and Benninger M.S. (1997) ‘The Voice Handicap Index (VHI): Development and Validation’ American Journal of Speech-Language Pathology, Vol 6(3), 66-70.

Laver, J., Wirz, S., Mackenzie, J. and Hillier, S. M. (1981) A Perceptual Protocol for the Analysis of Vocal Profiles Edinburgh University Department of Linguistics Work in Progress, 14: 139–155.

Zur K.B., Cotton S., Kelchner L., Baker S., Weinrich B. and Lee L. (2007) ‘Pediatric Voice Handicap Index (pVHI): a new tool for evaluating pediatric dysphonia’ Int J Pediatr Otorhinolaryngol, 71(1), 77‑82.