Acoustical effects of face masks on Speech Perception

The recent pandemic gave rise to the use of face masks, however, most people found it difficult to wear a mask. As per recent research in 2020 and 2021:

However, the global rise in cases proved that masks helped to reduce the cases and prevent fatalities. It also gave mental satisfaction to professionals returning to the office.

Many news articles & research papers have published the effects of masks on communication, including the University of Sydney & McGill University which looked into how face masks impair nonverbal communication between individuals. Therefore, looking at how we can make spaces comfortable to communicate with masks on is what needs to be defined.

Therefore, the objectives of this study were identified based on 3 key points.

  1. Understanding different types of facemasks
  2. Carrying out the relevant literature review
  3. Identify the study objectives

These are clearly shown in the image below.

Differences in face masks

 

Study Methodology

A bespoke framework was developed to analyze speech perception in an open-plan office.

 

1. Understanding the office condition

To carry out a clear understanding of the current office conditions the following steps were taken.

  • Measuring the sound pressure levels and reverberation time in the meeting rooms (a voice clip was recorded in the meeting room) & open-plan spaces
  • Surveying colleagues to gauge whether communication has been hindered due to masks

The measurements taken are highlighted in the table below:

2. Data collection

Once the office conditions were understood, data was collected by recording the audio using the three degrees of coverage on the speakers. The sentence recorded was “The hungry purple dinosaur ate the kind, zingy fox, the jabbering crab, and the mad whale and started vending and quacking.”  This audio file was then played with the 3 different setups.

  1. No mask
  2. Surgical mask
  3. N95 mask + face shield*

*was used to depict conditions in the UAE where governmental offices were asked to wear face shields, and many wore the face shield with N95 masks.

Each measurement was repeated twice, and an average was taken.

3. Analyse data

Quantitative Analysis:

Through the study, we understood that face masks degrade high-frequency speech sounds.

All masks tested attenuated high-frequency sounds above 1 kHz, with the worst attenuation above 4 kHz. These high-frequency signals are important for hearing sounds like “s,” “f,” and “th”.

Qualitative Analysis:

To further comprehend the quantitative data, a qualitative analysis was carried out among 15 participants– a mix of males and females. The participants were asked to hear the audio clip at a volume level of 5 (5 scrolls up on the volume bar of the phone). Out of the 15 participants, 67% were males and 40% were native English speakers. There were asked some general questions about speech perception and their understanding of the speech when the three audios were played. The two figures below show a detailed analysis of the same.

4. Conclusion

In terms of the overall perception of the results, 33% of the participants could understand all 3 audios clearly. The best masks overall were the surgical mask, which is made of nonwoven polypropylene fiber. The N95 respirator, which is made of thick nonwoven material and fits tightly on the face, blocked more sound than the surgical mask, and the face shield added further attenuation.

The materiality of masks & native/non-native English speakers has a direct impact on speech perception.

Recommendations & Opportunities

  • The pilot study was conducted during the restrictions on face-to-face data collection during the Covid-19 pandemic. These results should be confirmed under more controlled laboratory conditions.
  • Future studies can examine speech perception through masks in adults with aging-related hearing loss and other populations with communication impairments.
  • There is a huge opportunity to delve into the healthcare sector where masks are constantly worn in ERs.
  • Professionals in settings such as schools & hospitals should consider the trade-off between clear communication and health risks when selecting which masks to use in different contexts.

Contact details

Pooja Ganatra pooja.ganatra@burohappold.com  Pooja Ganatra | LinkedIn

(99)

Healthcare 133

Related Blog Posts