SLPOtherJournal of voice : official journal of the Voice Foundation2026

Performance of Nonlinear Energy Difference Ratio and Voice Type Component Profile Across Phoneme, Relative Sound Pressure Level, and Environment.

Ashvath Madhushankar, Jakob R Holm, Kelly Y Shih and 3 others

PMID 41775605

WHAT IT FOUND

NEDR stayed mostly stable for vowels and voiced fricatives, but changed with /s/, very soft speech, and noise.

VTCP moved more with loudness, sound type, and recording environment. Use the same sound and quiet room when interpreting them.

Key findings

01When /s/ was included, NEDR changed with sound type and relative loudness, but not with their combination.

02For /a/ across recording environments, NEDR changed with environment but not with relative loudness, and there was no environment-loudness interaction.

03The differences seen in pairwise comparisons across voice types were primarily driven by /s/.

STILL TO COME

How it was doneWhat they foundWhat it means for SLPs

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What it does not show

The study included only adults with normal voices, so it does not show how NEDR or VTCP perform in people with voice disorders. Loudness levels were relative to each participant's baseline and not calibrated to absolute sound pressure levels, so the paper cannot define clinical thresholds. Of 31 recruited participants, 27 were analyzed because some audio files could not be used due to the online decibel meter. Only sustained vowels and two alveolar fricatives were tested, and the environment comparison used only /a/, so connected speech and other sounds are not covered. Background noise may mask periodic energy differently across people, and this was not measured.

Declared interests

The authors declared no competing financial interests or personal relationships that could have influenced the work.

The easy way to misread this

Do not read a changed NEDR or VTCP score from /s/, very soft speech, or background noise as proof of voice pathology. In adults with normal voices, those task and recording conditions changed the scores, so the difference may reflect the measurement setup rather than the patient's voice.

Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →