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Voice Science Guides

Evidence-based guides on acoustic voice analysis for speech-language pathologists

Start here — reference guide

Voice Disorders: Classification, Assessment, and Acoustic Characterization

An overview of how voice disorders are grouped, who develops them, and how a voice evaluation is conducted — from case history and perceptual rating through to instrumental measurement. Each dimension links out to the guide that treats it in depth, so this is the place to start if you are not sure which measure answers your question.

Voice DisordersVoice EvaluationClinical GuideOverview
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October 25, 202624 min readJorge C. Lucero

Acoustic Voice Assessment End to End: The ASHA-Recommended Protocol in Practice

The instrumental voice protocol from microphone placement to a documented report. What the ASHA expert panel actually recommends—and why jitter and shimmer are not in its core set—plus the SPL calibration step most workflows skip, the analysis settings where protocols quietly fail, and the scale-dependence that makes a value interpretable only against values produced the same way.

Clinical ProtocolASHA GuidelinesRecording ProtocolSPL CalibrationTutorial
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September 3, 202614 min readJorge C. Lucero

Why One Number Isn't Enough: Dimension-Specific Voice Quality Indices

Most acoustic indices collapse voice quality into a single severity score—but a voice can be breathy without being rough, or strained without being breathy. Learn how four dimension-specific indices (severity, breathiness, roughness, strain) are computed from one sustained vowel, including the first published composite acoustic indices for roughness and strain, their derivation via QR factorization and OMP, diagnostic accuracy, and honest limitations.

Dimension IndicesCAPE-VRoughnessStrainMultiparametric
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June 14, 2026Updated September 22, 202614 min readJorge C. Lucero

The Singer's Formant: What It Is and How to See It in Your Voice

How does a trained voice carry over an orchestra without amplification? The answer is the singer's formant—a peak of acoustic energy near 3 kHz formed by the clustering of F3, F4, and F5. Learn the acoustics of vocal 'ring' and squillo, why center frequency varies by voice type, why high sopranos are different, and how to quantify it with the Singing Power Ratio (SPR).

Singer's FormantSinging VoiceSpectral AnalysisSPRAcoustic Analysis
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June 6, 202616 min readJorge C. Lucero

Glottal-to-Noise Excitation (GNE): The Breathiness Measure That Isn't HNR

GNE looks like another HNR, but it asks a different question—whether the noise in a voice comes from turbulent air escape or from irregular vibration. Learn what GNE measures, how it differs from HNR, the PVQD-derived typical range, and the sampling-rate trap that returns invalid values without warning.

GNEBreathinessAcoustic AnalysisClinical Guide
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May 10, 2026Updated September 1, 202614 min readJorge C. Lucero

Acoustic Voice Assessment via Telehealth: What Survives the Compression

Medicare telehealth for SLP services is extended through 2027—but can clinicians trust acoustic measurements collected over Zoom or Teams? Evidence shows mean f0 and expert perceptual ratings survive platform transmission, while HNR and L/H ratio are invalidated and CPPS is systematically biased downward. Learn why asynchronous recording is the defensible way to quantify voice remotely, and how to build a protocol that holds up.

TelehealthTelepracticeRecording ProtocolClinical Workflow
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May 9, 202615 min readJorge C. Lucero

MPT and DSI: A Clinical Implementation Guide

Maximum Phonation Time and the Dysphonia Severity Index are two of the most widely used objective voice measures—but small protocol differences and cross-system variability can produce misleading values. Learn the correct recording protocol, normative ranges, the Wuyts DSI formula, what each component measures, and the limitations clinicians need to know.

MPTDSIClinical ProtocolVoice Assessment
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May 8, 202616 min readJorge C. Lucero

CAPE-V and GRBAS for the Acoustic Era: Reconciling Perceptual and Acoustic Voice Assessment

No acoustic parameter "is" a CAPE-V dimension—but different parameters predict different ratings. Learn which measures track Severity, Breathiness, Roughness, and Strain, why one global index cannot replace four perceptual ratings, and how to use acoustic analysis to support (not substitute) clinical judgment.

CAPE-VGRBASPerceptual AssessmentClinical Guide
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March 27, 202618 min readJorge C. Lucero

Formant Analysis for Voice Clinicians: Beyond F0

Master vocal tract resonances for clinical practice. Learn F1/F2/F3 interpretation, gender-affirming voice therapy applications, resonant voice mechanisms, vowel space area for dysarthria, Praat settings by speaker type, and when formant analysis adds value.

FormantsGender-AffirmingResonanceDysarthriaAcoustic Analysis
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March 5, 202616 min readJorge C. Lucero

Vocal Biomarkers for Cognitive Screening: What SLPs Need to Know

The voice reveals more than voice quality—emerging research shows acoustic biomarkers can detect early cognitive impairment with up to 89% accuracy. Learn which parameters matter, current validation status, and what this means for speech pathologists as AI-driven screening approaches clinical deployment.

Vocal BiomarkersCognitive ScreeningAIEmerging Research
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February 20, 2026Updated September 7, 202618 min readJorge C. Lucero

Spectrogram Reading for SLPs: A Visual Guide to Voice Quality

The spectrogram is the most powerful visual tool in voice assessment—but many clinicians find it intimidating. Learn wideband vs narrowband analysis, the Titze/Sprecher signal typing system (Types 1-4) that decides which acoustic measures are valid, why signal type can change within a single recording, and how to read the visual patterns of breathiness, roughness, strain, and common pathologies.

SpectrogramVisual AnalysisClinical GuideVoice Signal Typing
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January 20, 202612 min readJorge C. Lucero

The Implicit Question: What AI Voice Analysis Actually Measures

Traditional acoustic measures ask explicit questions. AI models ask implicit ones—learned from data, encoded in training. As AI enters clinical voice assessment, understanding what question a model is actually asking becomes the central challenge.

AIPhilosophyMeasurementClinical AI
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January 20, 2026Updated September 1, 202618 min readJorge C. Lucero

Gender-Affirming Voice Therapy: Why Pitch Is Only Part of the Story

F0 explains only 41.6% of perceived gender—resonance, intonation, and prosody carry the rest. Evidence-based F0 reference bands, why formants and pitch must shift together, randomized trials of intonation training, hormone effects, and why client-reported outcomes (TWVQ) are the anchor.

Gender-AffirmingVoice TherapyF0 TargetsFormants
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December 20, 2025Updated September 2, 202617 min readJorge C. Lucero

Jitter and Shimmer: What They Really Tell You (And What They Don't)

Traditional perturbation measures aren't obsolete—but their validity depends on the signal, not the patient. Learn when jitter and shimmer are valid (Type 1 signals only), when they fail, why the 2018 ASHA protocol chose CPP, why Praat and MDVP values aren't interchangeable, and why vocal loudness must be controlled.

JitterShimmerPerturbation MeasuresClinical Guide
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November 15, 2025Updated September 1, 202614 min readJorge C. Lucero

Understanding Cepstral Peak Prominence (CPP): The Anchor Measure of Modern Voice Assessment

CPP is the acoustic voice-quality measure of the 2018 ASHA protocol, backed by meta-analytic evidence—and it works where jitter and shimmer fail. Learn the published cutoffs (14.45 dB vowel / 9.33 dB speech in Praat), why the same recording scores ~3 dB lower in ADSV, and why live telehealth audio must never be read against a cutoff.

CPPAcoustic AnalysisClinical Guide
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Educational Content: Articles on this pages are provided for educational purposes to support evidence-based clinical practice. Content is not intended as medical advice. Clinical decisions should be made by qualified healthcare professionals based on individual patient assessment.