Intelligibility testing of the MedicCom device

Communication is vital for teamwork, with breakdown in communication having adverse outcomes such as delay in procedures and administration of the wrong treatment.¹ During the COVID pandemic, wearing Personal Protective Equipment (PPE) such as respirators, made voices less intelligible, leading to frustration among the clinical staff, patients and relatives and an overall poor patient experience. We designed and built a medical voice amplifier (the MedicCom device) and undertook a laboratory evaluation of effect on intelligibility of speech in two different noise environments. We assessed intelligibility using a modified Matching Rhyme Test (participants heard 50 words and for each picked the word from six matched rhyming words). One group sat 2m from a person wearing a respirator (Force 8 half-mask) who spoke the test words, with the second group seated in another room linked by a long electrical cable. This enabled both groups to simultaneously listen to the same person (Fig 1). We used recorded ED background noise played at 50 dB and 60 dB. To detect a clinically significant difference of 10 in the test scores the minimum sample was 4. Testing was performed with six volunteers from Emergency Department staff. At 50 dB background noise (Figure 2), participants were able to hear the words significantly (t(10)=5.7; p<0.01) better in the respirator mask group (mean 36.3, SD 3.1) than the MedicCom group (mean 27.0, SD 3.3). However, when the background noise was increased to 60 dB, there was no significant difference (t(5) = -0.7; p= 0.52) between the mask group (mean 25.0, SD 5.5) and MedicCom group (mean 26.5, SD 3.9). With mask alone, increased background noise from 50 dB to 60 dB gave a significant reduction in intelligibility (t(7)=4.6; p<0.01), however this reduction in intelligibility with increased background noise did not occur in the MedicCom group (t(9)=0.26; p=0.80 This study showed that intelligibility of speech through the MediCom device was worse than with PPE at the lower background noise but did not change with increased background noise. In contrast, increasing background noise significantly reduced intelligibility of speech through a PPE mask.The impaired intelligibility using MediCom at low background noise is likely due to distortion from the throat microphone. With more background noise, the higher volume of the voice amplifier becomes an advantage, but it is not sufficient to be clinically useful. Future research should focus on improving the interface microphone used with the MediCom device (such as an in-mask microphone).