Influence of face surgical and N95 face masks on speech perception and listening effort in noise

Abstract

Daily life conversation relies on speech perception in quiet and noise. Due to the COVID-19 pandemic, the usage of face masks has become mandatory in many situations. Acoustic attenuation of sound pressure by the mask tissue reduces speech perception ability especially in noisy situations. Mask also impede the process of speech information from sight of the moving mouth (lip reading). In a prospective exploratory experimental study including 17 normal hearing participants, speech perception in noise and listening effort were measured with and without a surgical mask or an N95 mask between the speech signal and the listener. Additionally, the influence of the masks on the acoustic frequency spectrum was measured. Averaged over all noise signals, speech perception threshold in noise was significantly reduced by 1.6 dB (95% CI[1.0, 2.1]) by a surgical mask and by 2.7 dB (95% CI[2.2, 3.2]) using an N95 mask. The 50%-listening effort signal-to-noise ratio was not significantly increased by 0.58 dB (95% CI[0.4, 1.5]) by a surgical mask but significantly increased by 2.2 dB (95% CI[1.2, 3.1]) using an N95 mask. In acoustic measures the amplitudes were reduced by the mask tissue by up to 8 dB at frequencies above 1 kHz while no reduction was observed below 1 kHz. We conclude that face masks reduce speech perception and increase listening effort in different noise signals. Together with an additional interference by missing lip reading the compound effect of face masks would have a relevant impact on daily life communication already in normal hearing subjects.

Occlusion of lip movements impairs reconstruction of acoustic speech features and higher-level segmentational features in the presence of a distractor speaker

“…Face masks have been shown to impair acoustic details of the speech signal in several studies, with N95/FFP2 masks showing quite a strong attenuation in mid to high frequencies, while surgical face masks show only moderate influence on the acoustic speech signal (Caniato et al, 2021;Corey et al, 2020). Confirming this impact behaviourally, Rahne et al (2021) found impaired speech perception in noise when wearing a surgical face mask compared to no mask, while participants performed even worse when using an N95 mask. As well as reducing acoustic details, information transmitted via visual input is completely missing or severely reduced.…”

“…The adverse effect of face masks on speech comprehension has been investigated in various studies on a behavioural level (Brown et al, 2021;Giovanelli et al, 2021;Rahne et al, 2021;Toscano & Toscano, 2021;Yi et al, 2021). Despite the overall agreement of the adverse effects of face masks on speech comprehension, it has been unclear which features of speech processing are specifically affected.…”

“…In the ongoing Covid-19 pandemic, face masks have become a prevalent and effective measure around the globe to counteract the transmission of SARS-CoV 2 (Rahne et al, 2021). However, face masks pose issues in everyday listening situations.…”

Decreasing hearing ability does not lead to improved visual speech extraction as revealed in a neural speech tracking paradigm

“…There is some indication that the effect is stronger AV compared to A conditions (Figure 3), but not significantly. Previous studies showed acoustic degradations of speech features for speakers wearing a face mask (Corey et al, 2020; Rahne et al, 2021). Despite these mostly being restricted to higher frequencies, this might have an impact on listeners who have trouble hearing and need every information available to aid their speech processing (Motlagh Zadeh et al, 2019).…”

Sound Feedback for Social Distance: The Case for Public Interventions During a Pandemic

“…Hadley and Ward point close attention to the physical gestures used as a substitute for verbal exchange where background noises impair vocal comprehension [75]. The normalisation of face masks worn during conversation has been shown to degrade the acoustic quality of the voice as a result of suppressing higher frequency ranges, commonly depended upon to recognise articulations of consonant sounds [76][77][78]. This poses a further disadvantage to those hard of hearing [79] as well as non-native speakers, often more dependent on reading the face [80,81].…”