GRBAS (voice) assessment instrument

Abstract

The GRBAS scale is a widely utilized, perceptual assessment tool designed for the rapid evaluation and classification of voice quality in clinical settings. It serves as a crucial component of the standard voice examination performed by a Speech-language pathologist or an ENT physician. The GRBAS scale evaluates five distinct parameters of the voice, collectively addressing the severity and nature of vocal deviation. Each parameter is rated subjectively on a four-point ordinal scale, ranging from 0 (normal) to 3 (severe deviation), allowing for a standardized yet quick quantification of dysphonia.

Keywords

GRBAS, voice assessment, dysphonia, voice quality, perceptual scaling, laryngology, speech pathology, Hirano M

Authors

Hirano M (1981)

Purpose

The primary purpose of the GRBAS scale is to provide a standardized, quick, and reliable method for perceptually evaluating the severity and characteristics of a patient’s voice disorder. This instrument allows clinical professionals, such as the Speech-language pathologist and ENT physician, to document the baseline vocal status, monitor changes over time (e.g., following therapy or surgery), and facilitate communication regarding the patient’s vocal condition across multidisciplinary teams.

Its design emphasizes speed and clinical utility, making it exceptionally valuable in busy outpatient clinics where comprehensive acoustic or aerodynamic measurements may not be immediately feasible. By focusing on five core perceptual parameters, the scale ensures that critical aspects of voice quality are consistently addressed during initial screening and ongoing monitoring.

Construct

The GRBAS scale measures the perceptual construct of dysphonia severity through five distinct sub-constructs, each representing a primary dimension of vocal deviation. These dimensions are based on the auditory perception of the voice, reflecting how the underlying vocal fold physiology manifests in sound. The construct assumes that any vocal pathology can be effectively categorized and quantified using these five parameters.

The five components—Grade, Roughness, Breathiness, Asthenia, and Strain—are designed to capture the overall severity (Grade) while isolating specific acoustic features related to vocal fold vibration (Roughness), glottal insufficiency (Breathiness), lack of vocal power (Asthenia), and excessive laryngeal tension (Strain). The cumulative score and the profile across the dimensions provide a nuanced picture of the patient’s voice quality impairment.

Validity

While the source content does not provide specific statistical data on validity measures (e.g., construct, criterion, or concurrent validity), the GRBAS scale has achieved widespread clinical acceptance due to its face validity and ecological utility. Its parameters directly correspond to common clinical descriptions of dysphonia. Numerous independent studies have sought to correlate the perceptual ratings of GRBAS parameters with objective acoustic and aerodynamic measures, often finding moderate correlations, particularly for the ‘Grade’ and ‘Roughness’ dimensions.

The primary concern regarding validity often centers on listener bias and training effects, as the scale relies entirely on subjective human perception. However, when raters are adequately trained and calibrated, the scale is generally accepted as a valid clinical indicator of vocal status, particularly in the assessment of organic and functional voice disorders. Its enduring use across global clinical and research settings serves as practical evidence of its perceived clinical validity.

Reliability

Reliability of the GRBAS scale is primarily assessed through inter-rater and intra-rater agreement, as is typical for perceptual rating scales. The original source does not specify reliability coefficients, but subsequent research indicates that achieving high reliability is heavily dependent on the training and experience of the raters. Inter-rater reliability (consistency between different clinicians) is often reported as moderate to good, especially when clinicians adhere to strict operational definitions for each of the five parameters.

Intra-rater reliability (consistency of a single clinician over time) is generally reported to be higher than inter-rater reliability. Efforts to improve the reliability of the GRBAS scale often involve rigorous calibration sessions, where clinicians listen to and rate standardized voice samples. The four-point ordinal structure (0-3) is thought to contribute to reliability by limiting the potential range of subjective scoring compared to visual analogue scales.

Factor Analysis

Specific factor analysis results for the GRBAS scale were not included in the original source documentation. However, academic research frequently investigates the factor structure of the scale. Theoretically, the five parameters (G, R, B, A, S) are intended to measure distinct aspects of voice quality. Factor analysis studies often confirm that the ‘Grade’ (G) factor loads heavily as a general severity measure, while Roughness (R) and Breathiness (B) often emerge as distinct, primary factors reflecting different underlying physiological mechanisms.

Conversely, Asthenia (A) and Strain (S) sometimes show less consistent factor separation or may load onto other factors, depending on the population studied. Despite mixed findings in detailed factor analysis regarding the independence of all five sub-parameters, the clinical utility of maintaining all five dimensions remains high for detailed descriptive purposes in the assessment of dysphonia.

Instrument

Test Type: Observation / Perceptual Rating Scale

Format: The scale uses a four-point ordinal rating system (0 to 3) applied across five distinct parameters of voice quality.

Language Available: Originally developed in Japanese, the scale is widely adopted and used internationally, typically applied through the universal phonetic terms (G, R, B, A, S), making it language-independent for rating purposes. The source documentation is available in Dutch (Nederlands).

Population Group: Clinical population presenting with voice disorders (Dysphonia).

Age Group: Adults (Volwassenen).

Population Details: Applicable to patients presenting to a Speech-language pathologist or ENT physician with any form of vocal pathology, including functional, organic, or neurological voice disorders.

Test Methodology: The clinician listens to the patient’s sustained vowel phonation and/or connected speech and subjectively rates the perceived severity of each of the five parameters on the 0-3 scale (0 = normal, 1 = slight deviation, 2 = moderate deviation, 3 = severe deviation).

Keywords

laryngeal pathology, vocal folds, perceptual assessment, voice severity index, clinical phonetics, Hirano scale

Authors

Author ORCID Identifier: Not specified in source data.

Affiliation Email addresses: Not specified in source data.

Correspondence Address: Not specified in source data.

Permissions & Fee and Test Year

The GRBAS scale was first introduced in 1981 by Hirano M. Due to its status as a widely accepted clinical standard and methodology rather than a proprietary psychological test, the scale itself is generally used without specific licensing fees for clinical or academic purposes. Users must ensure appropriate training protocols are followed for reliable implementation. The original PDF documentation for the Explanation Form and the Measurement Instrument are available via the links provided in the references below.

Reference’s

Hirano, M. (1981). Clinical examination of voice. Vienna: Springer-Verlag.

The original PDF for the Explanation Form (Toelichtingsformulier) can be downloaded here: https://scales.arabpsychology.com/wp-content/uploads/instrumenten/137_1_N.pdf

The original PDF for the Measurement Instrument (Meetinstrument) can be downloaded here: https://scales.arabpsychology.com/wp-content/uploads/instrumenten/137_3_N.pdf

Items of the GRBAS (stem)beoordelingsinstrument

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

• ernst van de afwijking (G, grade)
• ruwheid (R, roughness)
• heesheid (B, breathiness)
• stemzwakte (A, asthenic)
• de gespannenheid van de stemgeving (S, strain)