10.14639/0392-100X-N1002
Objective. Among the different procedures used by the ENT, acoustic analysis of voice has become widely used for correct diagnosis of dysphonia. The instrumental measurements of acoustic parameters were limited during the COVID-19 pandemic by the common belief that a face mask affects the results of the analysis. The purpose of our study was to investigate the impact of surgical masks on F0, jitter, shimmer and harmonics-to-noise ratio (HNR) in adults. Methods. The study was carried out on a selected group of 50 healthy subjects. Voice samples were recorded directly in Praat. All subjects were trained to voice a vocal sample of a sustained /a/, at a conversational voice intensity, with no intensity or frequency variation, for the Maximum Phonation Time (MPT), wearing the surgical mask and then without wearing the surgical mask. Results. None of the variations in acoustic voice analysis detected wearing a surgical mask and not wearing a surgical mask were statistically significant. Conclusions. Our study demonstrates that the acoustic voice analysis procedure can continue to be performed with the use of a surgical mask for the patient, even during the COVID- 19 pandemic.
application/xml
1827-675X
1002
en
Maria Luisa Fiorella
https://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
surgical mask
Acoustic voice analysis in the COVID-19 era
Text.Serial.Journal
https://www.actaitalica.it/
41
COVID-19
2020-11-24
2020-07-19
2021-03-19
2021-03-24
1-5
1
Maria Luisa Fiorella
2021
10.14639/0392-100X-N1002
1
Otolaryngology Unit, Department of Biomedical Sciences, Neuroscience and Sensory Organs, University of Bari “Aldo Moro”, Italy
1827-675X
surgical mask
5
Acoustic voice analysis in the COVID-19 era
https://www.actaitalica.it/article/download/1002/458
41
ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:1-5; doi: 10.14639/0392-100X-N1002




COVID-19


Acoustic voice analysis in the COVID-19 era
L’analisi acustica della voce in era COVID-19
Giada Cavallaro, Vincenzo Di Nicola, Nicola Quaranta, Maria Luisa Fiorella
Otolaryngology Unit, Department of Biomedical Sciences, Neuroscience and Sensory Organs, University of Bari “Aldo Moro”, Italy


SUMMARY
Objective. Among the different procedures used by the ENT, acoustic analysis of voice
has become widely used for correct diagnosis of dysphonia. The instrumental measure-
ments of acoustic parameters were limited during the COVID-19 pandemic by the common
belief that a face mask affects the results of the analysis. The purpose of our study was to
investigate the impact of surgical masks on F0, jitter, shimmer and harmonics-to-noise ratio
(HNR) in adults.
Methods. The study was carried out on a selected group of 50 healthy subjects. Voice
samples were recorded directly in Praat. All subjects were trained to voice a vocal sample
of a sustained /a/, at a conversational voice intensity, with no intensity or frequency varia-
tion, for the Maximum Phonation Time (MPT), wearing the surgical mask and then without
wearing the surgical mask.
Results. None of the variations in acoustic voice analysis detected wearing a surgical mask
and not wearing a surgical mask were statistically significant.
Conclusions. Our study demonstrates that the acoustic voice analysis procedure can con-
tinue to be performed with the use of a surgical mask for the patient, even during the COV-      Received: July 19, 2020
ID-19 pandemic.                                                                                  Accepted: August 12, 2020
                                                                                                 Published online: November 24, 2020
KEY WORDS: COVID-19, acoustic voice analysis, Praat, dysphonia, surgical mask
                                                                                                 Correspondence
RIASSUNTO                                                                                        Giada Cavallaro
Obiettivo. Tra le diverse procedure diagnostiche di competenza otorinolaringoiatrica, l’a-       Otolaryngology Unit, Department of Biomedical
                                                                                                 Sciences, Neuroscience and Sensory Organs, Uni-
nalisi acustica della voce si rivela utile alla valutazione quantitativa della disfonia ma la
                                                                                                 versity of Bari “Aldo Moro”, Italy
misurazione strumentale dei parametri acustici è stata limitata durante la pandemia da           E-mail: giadacavallaro@live.it
COVID-19 essendo la mascherina chirurgica considerata comunemente come da ostacolo
nella registrazione della voce. Lo scopo del nostro studio è stato quello di analizzare l’im-
                                                                                                 Funding
patto della mascherina chirurgica su parametri vocali quali F0, jitter, shimmer e harmonic-      The authors received the “Research Projects
to-noise ratio (HNR).                                                                            of National Relevance 2017 n. 2017JNKCYZ”
Metodi. È stato studiato un campione di 50 soggetti eufonici utilizzando il programma            funding for this work.
Praat. I soggetti sono stati istruiti a fonare la vocale /a/ tenuta ad intensità di voce di
conversazione, senza variazioni di intensità o frequenza, per il Tempo Massimo Fonatorio         Conflict of interest
(TMF), con e senza mascherina chirurgica.                                                        The Authors declare no conflict of interest.
Risultati. L’analisi acustica eseguita con le due diverse modalità non ha rivelato differenze
statisticamente significative nei parametri vocali considerati.
                                                                                                   How to cite this article: Cavallaro G, Di
Conclusioni. Il nostro studio dimostra come la procedura diagnostica di analisi acustica
                                                                                                   Nicola V, Quaranta N, et al. Acoustic voice
della voce può essere eseguita sul paziente che indossa la mascherina chirurgica.                  analysis in the COVID-19 era. Acta Otorhi-
PAROLE CHIAVE: COVID-19, analisi acustica della voce, Praat, disfonia                              nolaryngol Ital 2021;41:1-5. https://doi.
                                                                                                   org/10.14639/0392-100X-N1002

Introduction                                                                                     © Società Italiana di Otorinolaringoiatria
                                                                                                 e Chirurgia Cervico-Facciale
During the ongoing COVID-19 pandemic caused by SARS-CoV-2, the World
Health Organization and other public health organisations agree that face                                       OPEN ACCESS

masks can limit the spread of respiratory viral diseases 1,2. Whether masks are                  This is an open access article distributed in accordance with
                                                                                                 the CC-BY-NC-ND (Creative Commons Attribution-Non-
useful depends on the mechanisms for transmission for SARS-CoV-2, which                          Commercial-NoDerivatives 4.0 International) license. The
are likely an association of contact, droplet and aerosol modes. Surgical face                   article can be used by giving appropriate credit and mentio-
                                                                                                 ning the license, but only for non-commercial purposes and
masks have been in use since the early 1900s to help prevent infection of                        only in the original version. For further information: https://
surgical wounds from staff-generated oral and nasal bacteria 3. Today, appli-                    creativecommons.org/licenses/by-nc-nd/4.0/deed.en




                                                                                                                                                             1
G. Cavallaro et al.




cations have evolved from prevention of patient infection           mer (apq3), shimmer (apq5), shimmer (apq11), shimmer
to prevention of employee exposure. However, there is on-           (dda) and mean harmonics-to-noise ratio (HNR).
going debate about the use of surgical masks as respira-
tory protection devices 4. For ENT specialists, dysphonia           Results
examination by laryngoscopy requires unavoidable contact
with the upper airway, and any reflex coughing or sneez-            The results are recorded as average and standard deviation
ing during procedures will cause direct contamination to            (SD). Results were then submitted to statistical analysis by
medical staffs and office workers 5,6. Among the different          comparing mean values of each parameter. All parameters
procedures used by the ENT, acoustic analysis of voice has          were analysed in the same patients during phonation with
become widely used for correct diagnosis of dysphonia,              surgical mask (SM) and without surgical mask (NSM). We
but the instrumental measurements of acoustic perturbation          used Student’s test with p = 0.05 significance level after
was limited during the COVID-19 pandemic by the com-                evaluating the t value in each parameter.
mon belief that a face mask affects the results of the analy-       As illustrated in Table I, the acoustic analysis showed that
sis. The purpose of our study was to investigate the impact         there was not a significant difference (at the 0.05 level) in
of surgical mask on F0, jitter, shimmer and harmonics-to-           median pitch values (Mean SM = 187.36; SD SM = 52.36;
noise ratio (HNR) in adults.                                        Mean NSM = 189.38; SD NSM = 55.52; p = 0.8523) and in
                                                                    the mean pitch values (Mean SM = 183.52; SD SM = 51.13;
                                                                    Mean NSM = 185.52; SD NSM = 55.12; p = 0.8513) in the
Materials and methods
                                                                    two different situations ( wearing surgical mask – not wear-
The study was carried out on a selected group of 50 healthy         ing surgical mask) (Tab. I).
subjects (20 men and 30 women, mean age 47 years, range             As can be seen in Table II, differences in HNR values
26-69) recruited among hospital staff of the ENT Depart-            were not significant (Mean SM = 20.91; SD SM = 3.44;
ment of the Polyclinic Hospital in Bari (South Italy).              Mean NSM = 20.92; SD NSM = 3.47; p = 0.9885). At
Participants were approached and informed about the study           the same time, significant differences were not noticed in
objectives and significance. All participants who agreed to         jitter or shimmer values (jitter local Mean SM = 0.327;
participate in the study signed an informed consent form,           SD SM = 0.134; Mean NSM = 0.298; SD NSM = 0.124;
previously approved by the local hospital Ethics Commit-            p = 0.2641; shimmer local Mean SM = 3.34; SD SM = 1.420;
tee.                                                                Mean NSM = 3.165; SD NSM = 1.572; p = 0.5605) (Tabs.
Inclusion criterion was ability to phonate and sustain a            III, IV). In conclusion, none of the variations in acoustic
vowel for at least 10 seconds. The participants were exclud-        voice analysis detected in the same patients with surgical
ed if they met any of the following criteria: reporting recent      mask and without surgical mask were statistically signifi-
voice problems or a voice disorder history, a condition that        cant.
might affect the normal voice function, any previous for-
mal voice training or voice therapy, any laryngeal, mouth,
                                                                    Discussion
or throat abnormality, or any respiratory infection for the
last 2 weeks before recording. The subjects who met selec-          Acoustic voice analysis is considered to be a very useful
tion criteria were recruited. The participants were asked to        technique for detection of voice disorders that can be de-
stand in front of a microphone (Samson Meteor Mic - USB             tected by analysing several acoustic parameters7. Subjec-
Studio Condenser Microphone) at a distance of 20 cm from            tive assessment methods, such as auditory perceptual anal-
the lips, in a quiet room (< 30 dB background noise). Voice         ysis, largely depend on the experience of professionals, and
samples were recorded directly in Praat. All subjects were          may lead to different results. This requirement encourages
trained to voice a vocal sample of a sustained /a/, at a con-       the use of objective measurement of voice. Processing of
versational voice intensity, always within 55 dB and 65 dB,         a speech signal is used to yield a set of voice parameters.
on average (not including recordings the average intensity          It allows detection of vocal fold pathologies, or other re-
of which was out of range), as constant as possible, with no        lated pathologies, by comparing patients’ data with that
intensity or frequency variation, for the Maximum Phona-            of other individuals having normal healthy voices 7. Voice
tion Time (MPT), wearing a surgical mask and then without           disorders require often voice therapy and other treatments
a surgical mask. The vocal parameters analysed with Praat           that are based on an initial assessment to quantify devia-
were median pitch, mean pitch, minimum pitch, maximum               tion from normal measures and an ongoing evaluation to
pitch, number of pulses, number of periods, jitter (local),         record the progress. Measuring treatment outcomes is the
jitter (rap), jitter (ppq5), jitter (ddp), shimmer (local), shim-   basic component of evidence-based practice. The objective



2
                                                                                           Performing acoustic analysis of voice despite COVID-19 safety measures




Table I. Acoustic analysis of median pitch, mean pitch, minimum pitch and maximum pitch values wearing surgical mask (SM) and not wearing surgical mask
(NSM). With significance level at 0.05, values obtained by Student t test (calculated) in the same patients with surgical mask and without surgical mask are not
statistically significant.
                     Median       Median pitch       Mean pitch         Mean pitch        Minimum pitch        Minimum          Maximum           Maximum
                      pitch           (Hz)               (Hz)               (Hz)                (Hz)             pitch            pitch              pitch
                       (Hz)           NSM                SM                 NSM                 SM                (Hz)             (Hz)              (Hz)
                       SM                                                                                        NSM               SM                NSM
 Mean            187.36               189.38              183.52             185.52               173.37          181.87           194.52               195.94

 Standard         52.36               55.52               51.13               55.12               54.15            59.05            54.63               56.47
 Deviation
 T-test        p = 0.8523         p = 0.8513            p = 0.4549          p = 0.8986



Table II. Acoustic analysis of the number of pulses, number of periods and of the HN (harmonics-to-noise ratio) values wearing surgical mask (SM) and not
wearing surgical mask (NSM). With significance level at 0.05, values obtained by Student t test (calculated) in the same patients with surgical mask and without
surgical mask are not statistically significant.
              Number of pulses            Number of pulses     Numbers of periods Numbers of periods                  Mean HNR                  Mean HNR
                      SM                         NSM                   SM                       NSM                      (dB)                     (dB)
                                                                                                                          SM                      NSM
 Mean               574.18                     575.00                      573.14                   574.00                 20.91                   20.92
 Standard           157.88                     168.76                      157.85                   168.76                 3.44                    3.47
 Deviation
 T-test                       p = 0.9800                                             p = 0.9791                                    p = 0.9885



Table III. Acoustic analysis of jitter values wearing surgical mask (SM) and not wearing surgical mask (NSM).With significance level at 0.05, values obtained by
Student t test (calculated) in the same patients with surgical mask and without surgical mask are not statistically significant.
                   Jitter              Jitter         Jitter rap      Jitter rap      Jitter ppq5          Jitter ppq5           Jitter ddp       Jitter ddp
                 local SM           local NSM             SM             NSM               SM                  NSM                   SM              NSM
                    (%)                 (%)               (%)             (%)             (%)                   (%)                  (%)              (%)
 Mean            0.327                0.298              0.184             0.159            0.182                0.165             0.535                0.533
 Standard        0.134                0.124              0.084             0.068            0.071                0.062             0.240                0.411
 Deviation
 T-test                  p = 0.2641                          p = 0.1051                             p = 0.2052                             p = 0.9764



Table IV. Acoustic analysis of shimmer values wearing surgical mask (SM) and not wearing surgical mask (NSM).With significance level at 0.05, values obtained
by Student t test (calculated) in the same patients with surgical mask and without surgical mask are not statistically significant.
                  Shimmer         Shimmer       Shimmer        Shimmer      Shimmer        Shimmer       Shimmer          Shimmer   Shimmer      Shimmer
                   local SM      local NSM      apq3 SM apq3 NSM apq5 SM apq5 NSM apq11 SM                                  apq11    dda SM      dda NSM
                      (%)            (%)           (%)            (%)          (%)            (%)            (%)           NSM (%)     (%)          (%)
 Mean              3.34          3.165           1.726             1.589           2.008        1.836        2.705         2.689           5.070         4.766
 Standard          1.420         1.572           0.840             0.974           1.061        0.897        1.087         1.194           2.531         2.922
 Deviation
 T-test                p = 0.5605                       p = 0.4531                    p = 0.3835                  p = 0.9443                  p = 0.5794


assessment of voice, especially acoustic analysis, has re-                             has investigated the effects of the use of a surgical mask
ceived our attention because of its comparatively low cost,                            on acoustic parameters. According to previous studies,
ease of application and quantitative output. Previous stud-                            one of the most investigated voice acoustic parameters has
ies 8,9 have found that fundamental frequency (F0) can be                              been voice perturbation 10,11. Subsequently, we investigated
affected by different factors, i.e., age, vocal fold length and                        parameters such as F0, jitter, shimmer and harmonics-to-
language or ethnological background. Until now, no study                               noise ratio (HNR) during phonation wearing surgical mask



                                                                                                                                                                 3
G. Cavallaro et al.




and then not wearing surgical mask. The fundamental fre-        and single-use gloves. Insofar as an asymptomatic patient
quency or mean pitch (F0) of a speech signal refers to the      may be infectious, the same precautions must be employed
approximate frequency of the (quasi-)periodic structure         whether the patient is ill with, suspected of having, or with-
of voiced speech signals. Jitter (%) is defined as cycle-to-    out any clinical evidence of COVID-19 infection 20. After
cycle and short-term perturbation in the fundamental fre-       the examination, the professional must carefully disrobe in
quency of the voice. The shimmer (%) is a cycle-to- cycle,      compliance with hygiene rules, with the immediate elimi-
short-term perturbation in the amplitude of voice. Another      nation of gloves, hair cap, mask and gown. The room where
acoustic parameter (HNR) is influenced by both the shim-        the examination is carried out must undergo air renewal as
mer and jitter and referred to as the mean ratio of harmon-     per legislation 20. Most of these best practice recommen-
ics to non-harmonics 12.                                        dations are not based on scientific data established for the
In accordance with such a high risk of infection, only emer-    COVID-19 infection, but come from what is known about
gency consultations and procedures should be performed          other viral respiratory infections.
by ENT specialists during the COVID-19 pandemic in areas        For ENT specialists, voice acoustic analysis is a very valu-
with confirmed SARS-CoV-2 cases 13. In China, Cheng et          able technique for voice disorders diagnosis and therapy
al. noted that the rate of work-related SARS-CoV-2 infec-       monitoring 21. Speech signal processing allows the extrac-
tion was higher among ENT specialists that in other medi-       tion of a set of voice parameters that may be used to diag-
cal specialties 14. During the lockdown of the population in    nose many pathologies of the vocal cords in individuals by
Italy, ENT activities were reduced to emergency treatments      comparison with healthy voice. The parameters obtained
and those that could not be deferred without constituting       by the acoustic analysis have the advantage of describing
a real loss of chance for the patient’s recovery or survival.   the voice objectively rather than subjective perceptual anal-
ENT specialists are exposed to SARS-CoV-2 infection             ysis, and they represent a useful method to objectify the
because of the necessity to examine the upper respiratory       dysphonia, even in the pandemic period. The use of the sur-
tract. At the same time, they perform procedures that gen-      gical mask provides the patient and operator with the right
erate aerosolised secretions and often bleeding 15. In the      protection necessary to perform this procedure, and at the
study by Krajewska et al. 16 ENT units are important for        same time it does not involve important alterations of the
preoperative testing for SARS-CoV-2: this should be per-        vocal parameters to be analysed. Several types of software
formed in all individuals undergoing high-risk procedures.      have been developed for acoustic analysis, namely, Praat 22,
The authors also assert that chest CT should be performed       LingWAVES 23, Multidimensional Voice Program 24 etc.
in patients before ENT interventions, because it could be of    The current study used Praat (version 6.1.16) for voice
great value in individuals with negative RT-PCR.                analyses, which is a computer software package for speech,
According to Tysome et al., high-risk procedures must           phonetic and voice analysis. It was first designed in 1992
be performed using enhanced personal protective equip-          by Paul Boersma and David Weenick from the Institute of
ment 17. As highlighted by Lescanne et al. 18, during ENT       Phonetic Sciences, University of Amsterdam. Praat can be
examinations or procedures that not need exposure to pro-       used on various operating systems and uses the finest algo-
jection/aerosolisation of organic material of human origin,     rithms including the most accurate algorithm of pitch anal-
the ENT medical team should wear clean outfits as well as       ysis, articulatory synthesis and gradual learning algorithm
single-use gloves in case of contact with a mucosa. If worn     for free variation. We used the inbuilt option of voice report
properly, a face mask is a disposable device that is used       in Praat pulses menu, which includes pitch and perturba-
to help block large-particle droplets, sprays, splashes, or     tion analyses. In particular, the voice samples collected for
splatters that may contain viruses and bacteria. It is used     perturbation measures were analysed by selecting the mid-
to create a physical barrier between the potential contam-      dle 3 seconds from the sound wave. Each acoustic signal
inants in the immediate environment and the mouth and           was perceptually examined for instability and visually dis-
nose of the wearer and it is also useful to block saliva and    played using Praat with an oscillogram and “Show inten-
respiratory secretions from the wearer to another 19. In our    sity” and “Show pulses” settings. We acoustically analysed
study, the surgical masks used were three-ply. This three-      the voice samples recorded by each participant wearing
ply material is made up of a melt-blown polymer, most           and not wearing the surgical mask in order to find objective
commonly polypropylene, placed between non-woven                voice measurements including the F0, jitter, shimmer, and
fabric. For examinations and procedures with exposure           HNR. The statistical comparison carried out between the
to projection/aerosolisation of organic material of human       parameters extracted with and without surgical mask did
origin, protection must be supplemented by wearing a sur-       not reveal any significant differences that would lead to an
gical mask, protective goggles, a single-use plastic apron      avoidance of the procedure for health safety reasons.



4
                                                                                     Performing acoustic analysis of voice despite COVID-19 safety measures




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