RU2525511C1 - Method for ergonomic qualimetry of ear protectors - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: objective characteristics are obtained from tone audiometry results and subjective characteristics are obtained by polling respondents, followed by calculation of the ergonomic factor of the ear protectors. The objective characteristics used are: effectiveness of protection from noise at octave frequency of 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, 8000 Hz. The percentage professionals for whom the use of the ear protectors did not lower the hearing threshold at said octave frequencies after replacement, is determined. The subjective characteristics used are: ringing effect - noise in the ears, pressure and strain in the ears, headache, noise and strain in the head, low working capacity, sleep disturbance, unpleasant feeding in area around ears, flushed skin in the area around ears, interference with professional activities in the ear protectors. The percentage of respondents without said subjective characteristics is determined. Also, the subjective characteristics used are: weight and size characteristics, effectiveness of the fastening system, easy usage, easy storage in unused state, quality of the head strap, safety of usage, compatibility of the ear protectors with equipment. The percentage of respondents evaluating said characteristics as "normal" and "satisfactory" is determined. The sufficiency of reducing noise is evaluated and the percentage of respondents evaluating the degree of reducing noise by the ear protectors as "sufficient" is determined. The obtained estimates are summed up and the ergonomic factor of the ear protectors is calculated. The ergonomic level of the ear protectors is evaluated as low, satisfactory, good or excellent based on the value of said factor.

EFFECT: method enables ergonomic qualimetry of any ear protectors in order to choose ear protectors by determining objective and subjective estimates of information characteristics.

3 tbl, 2 ex

Description

The present invention relates to the field of human life safety, and more specifically to ensuring the protection of a person from noise, and can be used when choosing anti-noise headphones and substantiating proposals for their improvement.

Of great importance for the choice of personal protective equipment (PPE) for a person in general and anti-noise headphones (PSN), in particular, is their ergonomics, which in general means adaptability for intended use, the presence of conditions, opportunities for a pleasant, easy use of the product or satisfaction of any any needs, needs. Since any PPE to one degree or another limits the mobility of a person (fetters movement, puts pressure on certain parts of the body, etc.), the ergonomics of PPE is a very important characteristic that directly affects the performance and reliability of the professional activity of a specialist using PPE. Experience convincingly indicates that an effective PPE, which has ergonomic disadvantages, is either not used by specialists at all or is used incorrectly, which significantly reduces its protective characteristics. An assessment of the ergonomics of PSN is obtained as a result of ergonomic qualimetry, however, the method of its implementation is not regulated by regulatory documents.

The closest the claimed invention is a test procedure for personal protective equipment for hearing organs from noise by threshold audiometry (see GOST R 12.4.211-99 "Occupational safety standards system. Personal protective equipment for hearing organs. Antinoise. Subjective method for measuring noise absorption.” Introduced action from 01.01.2002. - M .: IPK Publishing house of standards, 2000. - 10 p.).

The implementation of this method involves:

1) the selection of a group of 16 testers having an auditory threshold level when listening with headphones in each ear is not more than 15 dB for frequencies of 2000 Hz and not more than 20 dB for frequencies above 2000 Hz;

2) preparation of at least two models of anti-noise headphones;

3) the fitting of anti-noise headphones and instructing testers;

4) a change in the force of pressing the headphones to the head;

5) measurement of noise absorption with the implementation of a diffuse sound field and the use of acoustic signals filtered through a one-third octave band with geometric mean frequencies of 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 4000 Hz and 8000 Hz;

6) plotting the noise absorption by antinoise headphones and generating a test report.

However, this method has several disadvantages, the most significant of which are:

- ergonomic characteristics of PSN are not taken into account, directly affecting the working capacity and reliability of the professional activity of specialists using them;

- the study of noise absorption in a diffuse field provides an overestimation of the effectiveness of protection against noise;

- when conducting research, the peculiarities of the acoustic situation at the workplaces of specialists are not taken into account;

- for research, at least two models of anti-noise headphones are required;

- no calculation of the integral quantitative characteristics of the quality of PSHN is performed, which does not allow objectively comparing various samples of PSHN.

The technical task of the invention is the provision of ergonomic qualimetry of any samples of PSHN, which is essential to ensure high performance and reliability of the professional activity of specialists using them.

The technical result consists in providing the possibility of objective ergonomic qualimetry of anti-noise headphones based on the definition of objective and subjective assessments of informative characteristics.

The technical result is achieved by the fact that as objective characteristics use:

- the effectiveness of protection against noise of an octave frequency of 125 Hz (x ₁ is the percentage of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 125 Hz after a change),

- the effectiveness of protection against noise of an octave frequency of 250 Hz (x ₂ is the percentage of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 250 Hz after a change),

- the effectiveness of protection against noise of an octave frequency of 500 Hz (x ₃ is the percentage of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 500 Hz after a change),

- the effectiveness of protection against noise of an octave frequency of 1000 Hz (x ₄ is the percentage of specialists whose use of anti-noise headphones did not reduce hearing thresholds at an octave frequency of 1000 Hz after a change),

- the effectiveness of protection against noise of an octave frequency of 2000 Hz (x ₅ is the percentage of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 2000 Hz after a change),

- the effectiveness of protection against noise of an octave frequency of 4000 Hz (x ₆ is the percentage of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 4000 Hz after a change),

- the effectiveness of protection against noise of an octave frequency of 8000 Hz (x ₇ is the percentage of specialists whose use of anti-noise headphones did not reduce hearing thresholds at an octave frequency of 8000 Hz after a change),

and as subjective characteristics use:

- ringing (noise) in the ears (x ₈ - percentage of respondents who noted the absence of ringing (noise) in the ears),

- pressure and heaviness in the ears (x ₉ - percentage of respondents who noted a lack of pressure and heaviness in the ears),

- headache (x ₁₀ - percentage of respondents who noted the absence of a headache),

- noise and heaviness in the head (x ₁₁ - percentage of respondents who noted the absence of noise and heaviness in the head),

- decrease in working capacity (x ₁₂ - percentage of respondents who noted the absence of a decrease in working capacity),

- sleep disturbance (x ₁₃ - percentage of respondents who reported no sleep disturbance),

- weight and size characteristics (x ₁₄ - the proportion of respondents who rated weight and size characteristics as “normal”),

- the effectiveness of the fastening system (x ₁₅ - the proportion of respondents who rated the effectiveness of the fastening system as “satisfactory”),

- usability (comfort) (x ₁₆ - percentage of respondents who rated usability (comfort) as “satisfactory”),

- convenience of storage in an unused state (x ₁₇ - percentage of respondents who rated the convenience of storage in an unused state as “satisfactory”),

- headband quality (x ₁₈ - percentage of respondents who rated the quality of the headband as “satisfactory”),

- interference with professional activities in anti-noise headphones (x ₁₉ - percentage of respondents who noted the absence of interference with professional activity in anti-noise headphones),

- safety of use (x ₂₀ - percentage of respondents who rated safety of use as “satisfactory”),

- compatibility of anti-noise headphones with equipment samples (x ₂₁ - percentage of respondents who rated the compatibility of anti-noise headphones with equipment samples as “satisfactory”),

- discomfort in the parotid region (x ₂₂ - percentage of respondents who noted the absence of discomfort in the parotid region),

- redness of the skin in the parotid region (x ₂₃ - percentage of respondents who noted the absence of redness of the skin in the parotid region),

- sufficiency of noise reduction (x ₂₄ - percentage of respondents who rated the degree of noise reduction by anti-noise headphones as sufficient),

and on the basis of the estimates obtained, the ergonomics coefficient of the anti-noise headphones k = 7x ₁ + 7x ₂ + 7x ₃ + 7x ₄ + 7x ₅ + 5x ₆ + 5x ₇ + 4x ₈ + 5x ₉ + 3x ₁₀ + 4x ₁₁ + 2x ₁₂ + 2x _{13 is} calculated + 3x ₁₄ + 4x ₁₅ + 4x ₁₆ + 2x ₁₇ + 2x ₁₈ + 2x ₁₉ + 3x ₂₀ + 2x ₂₁ + 5x ₂₂ + 5x ₂₃ + 3x ₂₄ , the magnitude of which estimates the ergonomic level of noise reduction headphones as low (k <40), satisfactory (40≤k <70), good (70≤k <90) or excellent (k≥90).

In the aggregate of essential features of the claimed method significantly differs from analogues, as it provides:

- an integral quantitative characteristic of the most important ergonomic characteristics of PSHN (ease of dressing / removal, compatibility with other elements of equipment, lack of interference with professional activities, the effectiveness of the fastening system, etc.) when choosing one of the PSHN options for a particular socio-professional group of specialists,

- the use of lowering human hearing thresholds at different geometric mean octave frequencies compared with the study of noise absorption in a diffuse field (with the inclusion of studies at the geometric mean octave frequency of 2000 Hz) provides more realistic estimates of the effectiveness of antinoise headphones,

- the possibility of substantiating directions for improving the ergonomics of PSHN, which is essential to ensure high performance and reliability of the professional activities of specialists using them,

- Calculation of the assessment of ergonomics (ergonomic level) of any samples of PSN.

The essence of the proposed method is as follows.

1) Before the start of the work shift, specialists who are involved in the ergonomic qualimetry of PSN arrive at the medical center, where for 5 minutes each of them undergoes tonal audiometry in order to determine hearing thresholds at octave frequencies of 125 Hz, 250 Hz, 500 Hz, 1000 Hz , 2000 Hz, 4000 Hz and 8000 Hz.

2) The PSN sample, the ergonomics of which are evaluated, is given to the specialists for whom they are intended before the start of the work shift. Before that, if necessary, they carry out the adjustment of the PSHN and instruct them on the features of their donning / removal and operation. During the work shift, the correct operation of the PSHN is monitored by specialists.

3) Immediately after the end of the work shift, immediately after removing the PSN, specialists who are involved in ergonomic qualimetry arrive at the medical center where each of them has tonal audiometry, after which each specialist receives a questionnaire (table 1 - Questionnaire form) and fills out her, indicating any symbol opposite the score given to each characteristic of PSN. As a rule, the respondent is asked to sign a questionnaire in order to question him in more detail about the motives for issuing one or another assessment in the interest of improving PSN.

4) A study of the ergonomics of the PSN sample is carried out for one or several days (until the necessary information is received): before and after the completion of each work shift, items 1 and 3 are performed.

5) Upon completion of the study, summarize the results and calculate the ergonomics coefficient of PSN, for which, according to the results of tonal audiometry and questionnaire, the proportions are determined (for objective indicators: the ratio of the number of examined with a characteristic sign to the total number of examined, for subjective indicators, the ratio of the number of respondents who gave the interesting answer to the question of the questionnaire to the total number of respondents who answered this question of the questionnaire):

5.1) according to the results of tonal audiometry (objective indicators):

- the proportion of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 125 Hz (x ₁ ),

- the proportion of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 250 Hz (x ₂ ),

- the proportion of specialists for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 500 Hz (x ₃ ),

- the proportion of specialists whose use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 1000 Hz (x ₄ ),

- the proportion of specialists for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 2000 Hz (x ₅ ),

- the proportion of specialists for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 4000 Hz (x ₆ ),

- the proportion of specialists for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 8000 Hz (x ₇ ),

5.2) according to the results of processing the questionnaires (Table 1, subjective indicators):

- the proportion of respondents who noted the absence of ringing (noise) in the ears (x ₈ ),

- the proportion of respondents who noted the absence of pressure and heaviness in the ears (x ₉ ),

- percentage of respondents who reported no headache (x ₁₀ ),

- the proportion of respondents who noted the absence of noise and heaviness in the head (x ₁₁ ),

- the proportion of respondents who noted the absence of a decrease in working capacity (x ₁₂ ),

- the proportion of respondents who noted the absence of sleep disturbance (x ₁₃ ),

- the proportion of respondents who rated the overall dimensions as “normal” (x ₁₄ ),

- the proportion of respondents who rated the effectiveness of the fastening system as “satisfactory” (x ₁₅ ),

- the proportion of respondents who rated usability (comfort) as “satisfactory” (x ₁₆ ),

- the proportion of respondents who rated the convenience of storage in an unused state as “satisfactory” (x ₁₇ ),

- the proportion of respondents who rated the quality of the headband as “satisfactory” (x ₁₈ ),

- the proportion of respondents who noted the absence of interference with professional activities in noise-free headphones (x ₁₉ ),

- the proportion of respondents who rated the safety of use as “satisfactory” (x ₂₀ ),

- the proportion of respondents who rated the compatibility of anti-noise headphones with equipment samples as “satisfactory” (x ₂₁ ),

- the proportion of respondents who noted the absence of discomfort in the parotid region (x ₂₂ ),

- the proportion of respondents who noted the absence of redness of the skin in the parotid region (x ₂₃ ),

- the proportion of respondents who rated the degree of noise reduction by anti-noise headphones as sufficient (x ₂₄ ),

5.3) on the basis of the obtained estimates, the PPE ergonomics coefficient k = 7x ₁ + 7x ₂ + 7x ₃ + 7x ₄ + 7x ₅ + 5x ₆ + 5x ₇ + 4x ₈ + 5x ₉ + 3x ₁₀ + 4x ₁₁ + 2x ₁₂ + 2x _{13 is} calculated + 3x ₁₄ + 4x ₁₅ + 4x ₁₆ + 2x ₁₇ + 2x ₁₈ + 2x ₁₉ + 3x ₂₀ + 2x ₂₁ + 5x ₂₂ + 5x ₂₃ + 3x ₂₄ ,

5.4) according to the calculated value of the PPE ergonomics coefficient, its ergonomic level of PPE is estimated as low (k <40), satisfactory (40≤k <70), good (70≤k <90) or excellent (k≥90).

The developed method can be used to determine any samples of anti-noise headphones intended for any socio-professional groups of the population whose vital activity is carried out under the influence of noise.

Method implementation examples

Example 1. It is necessary to carry out the ergonomic qualimetry of three variants of antinoise headphones (PSN), which have the same acoustic efficiency and have the same cost, to select the headphones for use by aviation technicians providing the race of aircraft engines.

1) A group of 15 aeronautical technicians was identified who will be involved in the ergonomic qualimetry of PSN (five samples of each PSN variant are presented).

2) The samples of PSN, the ergonomic qualimetry of which must be carried out, were issued to aviation technicians before the start of the work shift. Before this, training was given on the features of putting them on / off and on operation. Studies were conducted over five shifts.

3) Before the shift, specialists involved in ergonomic qualimetry were sent to a medical center where they performed tonal audiometry. During the work shift, the correct operation of the sample by specialists was monitored by representatives of the PSN producer organization.

4) Immediately after the end of the work shift, specialists participating in ergonomic qualimetry were sent to a medical center where they performed tonal audiometry, after which they filled out a questionnaire (Table 1).

5) Upon completion of the study, the results obtained are summarized and processed (Table 2 - Ergonomic qualimetry results of anti-noise headphones). Cases when the respondent did not give an answer to some question of the questionnaire, as well as cases where the respondent indicated two mutually exclusive answers to the question of the questionnaire, were ignored.

6) The ergonomics of the first PSH sample should be assessed as excellent (90≤k, Table 2), and the ergonomics of the second and third PSH samples should be assessed as good (70≤k <90, Table 2); therefore, the first variant of PSH should be preferred.

Example 2. It is necessary to characterize the ergonomics of antinoise headphones (PSN) used by specialists of the test site working at technical inspection posts.

1) A group of 10 specialists has been identified who will be involved in the ergonomic qualimetry of 10 available samples of PSN.

2) The samples of PSN, the ergonomic qualimetry of which must be carried out, were issued to aviation technicians before the start of the work shift. Before this, training was given on the features of putting them on / off and on operation. Research was conducted over four shifts.

3) Before the shift, specialists involved in ergonomic qualimetry were sent to a medical center where they performed tonal audiometry. During the work shift, the correct operation of the sample by specialists was monitored by representatives of the PSN producer organization.

4) Immediately after the end of the work shift, specialists participating in ergonomic qualimetry were sent to a medical center where they performed tonal audiometry, after which they filled out a questionnaire (Table 1).

5) Upon completion of the study, the results obtained are summarized and processed (Table 3 - Ergonomic qualimetry results of anti-noise headphones). Cases when the respondent did not give an answer to some question of the questionnaire, as well as cases where the respondent indicated two mutually exclusive answers to the question of the questionnaire, were excluded from consideration.

6) The ergonomics of PSN should be assessed as satisfactory, since k = 63.28 (Table 3). Based on the results of ergonomic qualimetry (Table 3), it can be concluded that the specialists have the most complaints: the quality of the headband, the reliability of the mount on the head, compatibility with other types of equipment, and overall dimensions. These indicators are very important for the reliability and safety of professional activities of specialists, therefore, the manufacturer of noise-protective helmets should interview specialists about the reasons for the decrease in ratings and, based on the results of the survey, decide on the possibility of further development of helmets. In addition, studies aimed at improving the efficiency of noise protection (x ₁ ... x ₇ ) should be continued, since for about 30% of specialists at a number of octave frequencies it is not sufficient (Table 3).

The described method for the ergonomic qualimetry of anti-noise headphones was verified during experimental studies of PPE of the engineering staff of the Air Force from aircraft noise and found application in practice.

Table 1 Characteristic Possible assessment Mark the desired one (one of the ratings for each characteristic) Ringing (noise) in the ears due to the use of headphones is present absent A feeling of pressure and heaviness in the ears due to the use of headphones is present absent Headache due to the use of headphones is present absent Noise and heaviness in the head due to the use of headphones are present are absent Decreased performance due to the use of headphones is present absent Sleep disorders due to the use of headphones are present are absent Oversized headphone performance satisfactorily unsatisfactory Headphone Mounting System Efficiency satisfactorily unsatisfactory Convenience (comfort) of using headphones satisfactorily unsatisfactory Ease of storing headphones when not in use satisfactorily unsatisfactory Headband quality satisfactory unsatisfactory No interference with professional activities with headphones satisfactorily unsatisfactory Headphone Safety satisfactorily unsatisfactory Headphone compatibility with other items of equipment satisfactorily unsatisfactory Unpleasant sensations in the parotid region due to the use of headphones are available are absent Redness of the skin in the parotid region due to the use of headphones is available absent Headphone noise reduction sufficiency satisfactorily unsatisfactory

table 2 Indicator Value for the first version of headphones for the second version of headphones for the third option
headphone x ₁ 0.920 0.720 0.813 x ₂ 0.907 0.680 0.853 x ₃ 0.907 0.733 0.840 x ₄ 0.813 0.613 0.773 x ₅ 0.907 0.747 0,800 x ₆ 0.947 0.720 0.853 x ₇ 0.920 0.693 0.840 x ₁₆ 0.947 0.933 0.947 x ₁₇ 0.920 0.893 0.907 x ₁₉ 0.973 0.920 0.973 x ₂₀ 1,000 0.947 0.960 x ₂₂ 0.947 0.907 0.933 x ₂₄ 0.933 0.947 0.933 x ₂₆ 0.867 0.947 0.920 x ₂₇ 0.947 0.933 0.973 x ₂₈ 0.853 0.907 0.853 x ₂₉ 0.933 0.920 0.960 x ₃₀ 0.920 0.933 0.920 x ₃₁ 0.907 0.907 0.907 x ₃₂ 0.960 0.960 0.960 x ₃₃ 0.960 0.920 0.960 x ₃₄ 0.933 0.933 0.933 x ₃₅ 0.947 0.893 0.947 x ₃₇ 0.853 0.813 0.747 k 91.66 81,979 87,911

Table 3 Indicator Value x ₁ 0.70 x ₂ 0.66 x ₃ 0.64 x ₄ 0.74 x ₅ 0.62 x ₆ 0.64 x ₇ 0.66 x ₁₆ 0.80 x ₁₇ 0.54 x ₁₉ 0.82 x ₂₀ 0.78 x ₂₂ 0.96 x ₂₄ 0.98 x ₂₆ 0.30 x ₂₇ 0.28 x ₂₈ 0.24 x ₂₉ 0.52 x ₃₀ 0.24 x ₃₁ 0.54 x ₃₂ 0.54 x ₃₃ 0.38 x ₃₄ 0.66 x ₃₅ 0.86 x ₃₇ 0.78 k 63.28

Claims (1)

A method for the ergonomic qualimetry of anti-noise headphones, including determining objective values from the tonal audiometry results and obtaining subjective characteristics by questioning respondents, followed by calculation of the ergonomics coefficient of anti-noise headphones, characterized in that the following are used as objective characteristics:
- the effectiveness of protection against noise of an octave frequency of 125 Hz: x ₁ - the proportion of respondents for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 125 Hz after a change,
- the effectiveness of protection against noise of an octave frequency of 250 Hz: x ₂ - the proportion of respondents for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 250 Hz after a change,
- the effectiveness of the protection against noise of an octave frequency of 500 Hz: x ₃ - the percentage of respondents who have used anti-noise headphones did not reduce hearing thresholds at an octave frequency of 500 Hz after a change,
- the effectiveness of protection against noise of an octave frequency of 1000 Hz: x ₄ - the proportion of respondents for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 1000 Hz after a change,
- the effectiveness of protection against noise of an octave frequency of 2000 Hz: x ₅ - the proportion of respondents for whom the use of anti-noise headphones did not lead to a decrease in hearing thresholds at an octave frequency of 2000 Hz after a change,
- the effectiveness of protection against noise of an octave frequency of 4000 Hz: x ₆ - the proportion of respondents for whom the use of anti-noise headphones did not reduce hearing thresholds at an octave frequency of 4000 Hz after a change,
- the effectiveness of protection against noise of an octave frequency of 8000 Hz: x ₇ - the proportion of respondents who have used anti-noise headphones did not reduce hearing thresholds at an octave frequency of 8000 Hz after a change,
and as subjective characteristics use:
- ringing - tinnitus: x ₈ - percentage of respondents who noted the absence of ringing - tinnitus,
- pressure and heaviness in the ears: x ₉ - percentage of respondents who noted a lack of pressure and heaviness in the ears,
- headache: x ₁₀ - percentage of respondents who reported no headache,
- noise and heaviness in the head: x ₁₁ - percentage of respondents who noted the absence of noise and heaviness in the head,
- decrease in working capacity: x ₁₂ - percentage of respondents who noted the absence of a decrease in working capacity,
- sleep disturbance: x ₁₃ - percentage of respondents who noted the absence of sleep disturbance,
- overall dimensions: x ₁₄ - percentage of respondents who rated the overall dimensions as “normal”,
- the effectiveness of the fastening system: x ₁₅ - the proportion of respondents who rated the effectiveness of the fastening system as “satisfactory”,
- usability - comfort: x ₁₆ - percentage of respondents who rate usability - comfort as “satisfactory”,
- convenience of storage in an unused state: x ₁₇ - percentage of respondents who rated the convenience of storage in an unused state as “satisfactory”,
- headband quality: x ₁₈ - percentage of respondents who rated the quality of the headband as “satisfactory”,
- interference with professional activities in anti-noise headphones: x ₁₉ - percentage of respondents who noted the absence of interference with professional activity in anti-noise headphones,
- safety of use: x ₂₀ - percentage of respondents who rated safety of use as “satisfactory”,
- compatibility of anti-noise headphones with equipment samples: x ₂₁ - percentage of respondents who rated the compatibility of anti-noise headphones with equipment samples as “satisfactory”,
- discomfort in the parotid region: x ₂₂ - percentage of respondents who noted the absence of discomfort in the parotid region,
- redness of the skin in the parotid region: x ₂₃ - percentage of respondents who noted the absence of redness of the skin in the parotid region,
- sufficiency of noise reduction: x ₂₄ - percentage of respondents who rated the degree of noise reduction by anti-noise headphones as sufficient,
and on the basis of the estimates obtained, the ergonomic coefficient of the anti-noise headphones k = 7x ₁ + 7x ₂ + 7x ₃ + 7x ₄ + 7x ₅ + 5x ₆ + 5x ₇ + 4x ₈ + 5x ₉ + 3x ₁₀ + 4x ₁₁ + 2x ₁₂ + 2x _{13 is} calculated + 3x ₁₄ + 4x ₁₅ + 4x ₁₆ + 2x ₁₇ + 2x ₁₈ + 2x ₁₉ + 3x ₂₀ + 2x ₂₁ + 5x ₂₂ + 5x ₂₃ + 3x ₂₄ , the magnitude of which estimates the ergonomic level of anti-noise headphones as low k <40; satisfactory 40≤k <70, good 70≤k <90 or excellent k≥90.