Characterization of Source-Filter Interactions in Vocal Vibrato Using a Neck-Surface Vibration Sensor: A Pilot Study.
Rosemary A Lester-Smith, Elaina Derrick, Charles R Larson
PMID 34649740WHAT IT FOUND
In nine singers, a neck vibration sensor captured pitch vibrato just as well as a microphone, but missed the faster intensity wobble seen in audio.
This confirms the microphone picks up vocal tract filtering effects that the neck sensor does not.
Key findings
01The rate of intensity modulation was significantly higher in the microphone signal than in the neck-surface vibration sensor signal.
02The rate and extent of fundamental frequency modulation were equivalent between the neck-surface vibration sensor and the microphone.
03The difference in intensity modulation rate was larger for vowels where the first and second formant frequencies are closer together.
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 nine healthy singers, so findings may not apply to patients with voice disorders. The microphone was positioned close to the mouth, which can affect sound pressure level estimates, particularly at lower frequencies. Vocal health was assessed only by self-report, not by clinical examination. The study used a specific piezoelectric sensor; results may differ with other accelerometer types. Exclusion of the first modulation cycle in some trials due to signal artifacts may have influenced average extent calculations.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not assume neck-surface vibration sensors are interchangeable with microphones for assessing vocal intensity variability. The sensor missed the faster rate of intensity modulation seen in the microphone signal, meaning it does not capture the full acoustic picture of vibrato or potentially vocal tremor.