COVID-19: Acoustic Measures of Voice in Individuals Wearing Different Facemasks.
Ashwini Joshi, Teresa Procter, Paulina A Kulesz
PMID 34261582WHAT IT FOUND
Compared with no mask, the masks did not significantly change voice volume, pitch, or first formant in nineteen adults with normal voice.
Some mask combinations differed from each other.
Key findings
01Compared with no mask, the masks did not have a significant impact on intensity, fundamental frequency, or first formant frequency.
02For sustained /a/ at 1 ft, the KN95 plus surgical plus face shield condition had higher intensity than the KN95 condition (81.97 dB SPL vs 78.54 dB SPL).
03For sustained /a/, the KN95 plus surgical plus face shield condition had lower smoothed cepstral peak prominence than the KN95 plus surgical condition (12.17 dB vs 13.02 dB).
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Nineteen adults with normal voice participated, so the results do not show how masks affect people with voice disorders or other communication problems. One female participant's KN95 recording was unavailable, so one participant's data were missing for one mask condition. Testing used sustained vowels in a quiet room, not connected speech or background noise, so it does not answer how masks affect everyday conversation. Participants were told to produce /a/ the same way with each mask, but they may have changed effort to keep output constant, which cannot be separated from the mask effect. Age differences were not examined. Results may not apply to other mask brands or materials, especially cloth masks.
The easy way to misread this
Do not conclude that masks have no effect on voice. The study found no significant difference compared with no mask for intensity, fundamental frequency, and first formant, but the KN95 plus surgical plus face shield condition differed from KN95 alone and from KN95 plus surgical. The sample was nineteen adults with normal voice, and the contribution of each added layer cannot be separated.