The program for calculating the sound pressure of the alert system. Calculation of the speech alert system: formulas, theoretical calculations, an example of calculation

The designed building should be equipped with devices of people alerts about the fire of 2 type.

To notify people about the fire will be used by the Lighthouse-12-3m (Electrical Engineering and Automation LLC, Russia, Omsk) and light alarms "TS-2 SVT1048.11.110" (Tablo "Exit") connected to the device C2000-4 (CJSC NVP "BOLID").

For a network alert for fire, fire-resistant KPSEng cable (A) -FRLS-1x2x0.5 is used.

For email The supply of equipment for the voltage U \u003d 12 V is used by the source of the reserved email. Nutrition "Rip-12" isp. 01 with rechargeable EMK battery. 7 A h. Rechargeable batteries of the source of email. Nutrition provide equipment for at least 24 hours in standby mode and 1 hour in fire mode when disconnecting the main source of emitalization.

Basic requirements K. Sowe Followed in the NPB 104-03 "Systems of alert and managing the evacuation of people in the fires in buildings and facilities":

Based on the geometric size of the premises, all rooms are divided only to three types:

• "Corridor" - length exceeds width of 2 or more times;
• "Hall" - an area of \u200b\u200bmore than 40 sq.m. (This calculation does not apply).

In the room "Room" place one infidel.

In the air, the sound waves fade due to viscosity of air and molecular attenuation. The sound pressure is weakening in proportion to the slope of the distance (R) from the alarm: F (R) \u003d 20 Lg (1 / R). Figure 1 shows a graph of impact of sound pressure depending on the distance to the sound source F (R) \u003d 20 Lg (1 / R).

Fig. 1 - a graph of impact of sound pressure depending on the distance to the sound source F (R) \u003d 20 LG (1 / R)

To simplify the calculations, the table below shows the table of real values \u200b\u200bof sound pressure levels from the beacon "Mayak-12-3m" at various distances.

The table is the sound pressure generated by a single batch when it is turned on by 12V at a different distance from the alarm.

On floor plans indicate the geometric dimensions and the area of \u200b\u200beach room.

In accordance with the earlier assumption, we divide them into two types:

• "Room" - an area of \u200b\u200bup to 40 sq.m;
• "Corridor" - Length exceeds width of 2 or more times.

In place of the "room" type is allowed by one units.

In place of the "Corridor" type - several signs will be placed, evenly located on the room.

As a result - determining the number of bisteners in a particular room.

The choice of the "calculated point" - the point on the sounding plane in this room, as much as possible from the alarm, in which it is necessary to provide a sound level of at least 15 dB above the permissible sound level of constant noise.

As a result, the definition of the length of a straight line connecting the point of fastening the fastener with the "calculated point".

The calculated point is the point on the sounding plane in this room, as much as possible from the bunch, in which it is necessary to provide a sound level of at least 15 dba above the permissible level of sound noise, according to the NPB 104-03 of clause 3.15.

Based on the SNiP 23-03-2003 of clause 6 of the "norm of permissible noise" and the "Table 1" given in the same place, we derive the values \u200b\u200bof the permissible level of noise for the dormitory of workers' professionals is 60 dB.

When calculating, we should consider the attenuation of the signal when passing through the doors:

• fire-prevention -30 dB (a);
• standard -20 dB (a)



Legend

We will take the following conditional notation:

• N under. - Height suspension height;
• 1.5m - the level of 1.5 meters from the floor, at this level there is a visual plane;
• h1 - excess above the level of 1.5 m to the suspension point;
• W - width of the room;
• D - the length of the room;
• R is the distance from the alarm to the "calculated point";
• L is the projection R (the distance from the units to the level of 1.5 m on the opposite wall);
• S is the sound area.

5.1 Calculation for the room "Room"

We define the "calculated point" - the point that is maximally removed from the alarm.

For suspension, "smaller" walls that oppose the length of the room are selected, in accordance with the NPB 104-03 in clause 3.17.



Fig. 2 - vertical projection of the wall fastening of the NPB

An insistence we have in the middle of the "room" - in the center of the short side, as shown in Fig.3



Fig. 3 - Owner's location in the middle of the "room"

In order to calculate the size R, it is necessary to apply the Pythagora theorem:

• D - the length of the room, in accordance with the plan is 6.055 m;
• W - width of the room, in accordance with the plan is 2.435 m;
• If the firm will be placed above 2.3 m, then instead of 0.8 m, it is necessary to take the size H1 exceeding the height of the suspension over the level of 1.5 m.

5.1.1 Determine the sound pressure level at the calculation point:

P \u003d RDB + F (R) \u003d 105 + (- 15.8) \u003d 89.2 (dB)

• PDB is the sound pressure of the loudspeaker, according to those. information on the beacon "Mayak-12-3M" iso 105 dB;
• F (R) - the dependence of the sound pressure on the distance is -15.8 dB in accordance with Fig. 1 when R \u003d 6.22 m.

5.1.2 Determine the magnitude of the sound pressure, in accordance with the NPB 104-03 of paragraph 3.15:

5.1.3 Checking the correctness of the calculation:

P \u003d 89,2\u003e r rd \u003d 75 (condition is executed)

Sowe in a protective room.


5.2 Calculation for the room "Corridor"

Owners are placed on one wall of the corridor with an interval of 4-digra. The first is placed at a width distance from the entrance. The total number of bisteners is calculated by the formula:

N \u003d 1 + (d - 2 * w) / 3 * sh \u003d 1+ (26,78-2 * 2,435) / 3 * 2,435 \u003d 4 (pcs.)

• D - the length of the corridor, in accordance with the plan equal to 26.78 m;
• W is the width of the corridor, in accordance with the plan is 2.435 m.

The number is rounded to the whole value in the most side. Placing the alarms is represented in Fig. four.



Fig.4 - Placing the alarm in the room "Corridor" with a width of less than 3 meters and the distance "to the calculated point"

5.2.1 Determine the calculated points:

"Calculated point" is located on the opposite wall at a removal of two widths from the axis of the units. "

5.2.2 Determine the sound pressure level at the calculation point:

P \u003d RDB + F (R) \u003d 105 + (- 14.8) \u003d 90.2 (dB)

• PDB is the sound pressure of the loudspeaker, according to those. information on the beacon "Mayak-12-3M" is 105 dB;
• F (r) - the dependence of the sound pressure on the distance is -14.8 dB in accordance with Fig.1 when R \u003d 5.5 m.

5.2.3 Determine the magnitude of the sound pressure, in accordance with the NPB 104-03 of paragraph 3.15:

R R.T. \u003d N + zd \u003d 60 + 15 \u003d 75 (dB)

• N is a permissible level of constant noise, for hostels is 75 dB;
• Health of sound pressure equal to 15 dB.

5.2.4 Checking the correctness of the calculation:

P \u003d 90,2\u003e p rd \u003d 75 (condition is performed)

Thus, as a result of calculations, the selected type of the beacon of the Mayak-12-3m provides and exceeds the value of the sound pressure, thereby ensuring a clear audibility of sound signals Sowe in a protective room.

In accordance with the calculation, we will execute the arrangement of sound units, see Fig.5.



Fig.5 - Plan for posting for ONM. 0.000

In accordance with those who have entered into force in 2003. New fire safety standards, when designing requires specified sound levels. The document has a reference to the sound level measurement methodology, but there are no references to how to correctly calculate the required amount and the power of loudspeakers.

Let's try to paint the procedure for calculating alerts by steps.

1. It is necessary to determine the number of loudspeakers to ensure uniform sound allocation.

• rupore .............................................. 30-45 about
• searchlight ....................................... 30-45 o
• wall .............................................. 75-90 about
• ceiling ............................................ 80-90

Also, according to the installation experience, we can assume that it is allowed to place the ceiling loudspeakers after the distance equal to the height of the ceiling (the uniformity of the sound will be quite mediocre, but the NPB standards will double. If uniform voice is required, then it will be necessary to install the height of the ceiling. "). Wall loudspeakers are installed through the distance equal to the width of the corridor (room). And the ripples and the projectors are placed so that the places of cluster of people fall into the radiation diagram. When installing wall and horn loudspeakers, you need to adhere to the rule if you want to install several syncons in one area, it is better to install them in the center and send them to different directions than to put them on the walls and direct to the center. Splitting and quality in the latter case will be much worse.

2. Determine the noise level in the room. To do this, it can be measured or use the table with exemplary levels for various types of rooms.

3. The broadcast level must exceed the noise level on:

• for background music .................................. by 5-6db
• for emergency alert ..................... by 7-10db.
• for high-quality music ........................... for 15-20db

4. To account for loosening the sound level from the distance (within the directional diagram), you can use the table:

5. To account for an increase in sound level, depending on the input power, you can use the table:

6. In order to calculate the level of sound pressure at the required distance, you can use the simplified formula:

SPL (dB) \u003d SPL Passport - SPL attenuation + SPL Zoom

SPL (DB) - level at the required distance in the directional diagram

SPL passport - sound pressure level by passport at a distance of 1m (dB / W / m)

SPL attenuation - Level of attenuation depending on the distance (see table)

SPL Zoom - - the level of increase depending on the input power (see table)

From the above formula, it is easy to calculate the required power for a single loudspeaker. Having summarizing the power of loudspeakers, you can calculate the total power of the amplifier. The power of the amplifier is recommended to choose with a 20% power supply. When operating the system, you can make sure that.

For example: there is a commercial premises with dimensions of 20x30m with a height of the ceilings 3m. It takes it to voice the background music, but taking into account the possibility of emergency alert.

For uniform voice, it will take 20: 3-1 \u003d 5 rows of 30: 3-1 \u003d 9 pcs. Total 45 pcs.

The sound level at a distance of 1, 5 m from the loudspeaker (the height of the ceiling is the growth of the lowest person) should be at least 63 + 7 \u003d 70 dB. Therefore, if you use the loudspeakers of ART-01 (inter-m) with a capacity of 1 W, (according to the passport, the sound pressure level at a distance of 1 m is 90 dB.), Formula will acquire a view:

SPL (sound pressure level) \u003d 90-3 + 0 \u003d 87 dB. What is more than 70. so that these loudspeakers are suitable for visiting this room. And in principle, if only an emergency alert is needed, the quantity may be even less. (You can recalculate yourself).

If you don't want to bother with "complex" mathematical calculations at all, you can always use any program for calculating the number of loudspeakers for example from the company TOA. When using equipment from other manufacturers, it is necessary to consider the difference between their sound pressure from the selected type. You can download alert system for calculating (8,2MB)

Are the most important component of fire protection systems. In the process of designing alert systems, an electroacoustic calculation is performed. The basis for electro-acoustic calculation is the set of rules developed in accordance with Article 84 of the Federal Law of the Federal Law of the FZ-123 SP 3.13130.2009 of July 22, 2008. This article is based on the following main points of the Code of Rules.

• 4.1. SOUN Sound signals must provide a common sound level (the sound level of constant noise together with all signals produced by the alarms) at least 75 dBA at a distance of 3 m from the alarm, but not more than 120 dBA at any point of protected room
• 4.2. SOUN Sound signals should provide a sound level of at least 15 dba above the permissible sound level of constant noise in the protective room. Measuring the sound level should be carried out at a distance of 1.5 m from the floor level
• 4.7. Installation of loudspeakers and other speech alards in protected premises should exclude a concentration and uneven distribution of reflected sound.
• 4.8. The number of sound and speech fire fighters, their alignment and power must provide the sound level in all places of permanent or temporary stay of people in accordance with the norms of this Code of Rules

The meaning of the electro-acoustic calculation is reduced to determining the level of sound pressure at the calculated points - in places of permanent or temporary (probable) stay of people and comparing this level with recommended (regulatory) values.

In the voiced room there is a different kind of noise. Depending on the purpose and features of the room, as well as the time of day, the noise level varies. The most important parameter in the calculation is the value of average noise. Noise can be measured, but it is more convenient to take it from ready-made noise tables:

Table 1

In order to hear sound or speech information, it should be louder than noise by 3DB, i.e. 2 times. The amount of 2 is called the reserve of sound pressure. In real conditions, the noise is changing, so for a distinct perception of useful information against the background of noise, the pressure supply of D.B is not less than 4 times - 6 dB, according to regulations - 15DB.

Satisfying the conditions set out in paragraphs 4.6, 4.7 of the Code of Rules, is achieved by organizational events - the correct arrangement of loudspeakers, preliminary calculation:

• loudspeaker sound pressure,
• sound pressure at the calculation point
• effective area with a voiced one loudspeaker,
• the total number of loudspeakers needed to voicing a certain territory.

The criterion for the correctness of the electroacoustic calculation is the following conditions:

1. Sound pressure of the selected loudspeaker D.B. "At least 75 dba at a distance of 3 m from the alarm", which corresponds to the magnitude of the sound pressure of the loudspeaker not lower than 85DB.
2. Sound pressure at the calculation point D.B. Above the level of average noise indoors for 15 DB.
3. For ceiling loudspeakers, it is necessary to take into account the height of their installation (the height of the ceilings).

If all 3 conditions are completed - the electroacoustic calculation is made, if not, then the following options are possible:

• select a loudspeaker with greater sensitivity (sound pressure, dB),
• select a loudspeaker with greater power (W),
• increase the number of loudspeakers
• change loudspeaker arrangement scheme.

2. Input parameters for calculation

Input parameters for calculations are taken from the technical task (TK) (provided by the Customer) and the technical characteristics of the designed equipment. The list and number of parameters may vary depending on the situation. Exemplary input are shown below.

Loudspeaker Parameters:

• PG - Power of the loudspeaker, W,
• SDN - Width of the ordeal diagram, hail.

Room Parameters:

• N. - noise level indoors, dB,
• N. - the height of the ceilings, m,
• a. - Length of the room, m,
• b. - width of the room, m,
• SP. - room area, m2.

Additional data:

• Here - sound pressure, dB
• r. - distance from the loudspeaker to the calculation point.

Area of \u200b\u200bvoiced premises:

SP \u003d A * B

3. Calculation of the sound pressure of the loudspeaker

Knowing the rated power of the loudspeaker (RWT) and its SPL sensitivity (SPL from the English. Sound Pressure Level is the sound pressure level of the loudspeaker measured at 1W power, at a distance of 1 m), you can calculate the sound pressure of the loudspeaker, developed at a distance of 1m from the emitter.

• SPL - loudspeaker sensitivity, dB,
• RWT - Power of the loudspeaker, W.

The second term in (1) is called the rule of "power doubling" or the "three decibel" rule. The physical interpretation of this rule - with each doubling of the source power, its sound pressure level increases by 3DB. This dependence can be submitted tables and graphically (see Fig. 1).

Fig.1. The dependence of sound pressure from power

4. Calculation of sound pressure

To calculate sound pressure in a critical (calculated) point, it is necessary:

1. Select the calculation point
2. Estimate the distance from the loudspeaker to the calculation point
3. Calculate the sound pressure level at the calculation point

As a calculated point, we choose the place of possible (probable) finding people most critical in terms of position or removal. The distance from the loudspeaker to the calculation point (R) can be calculated or measured by the device (rangeference).

Calculate the dependence of sound pressure from the distance:

• r. - distance from the loudspeaker to the calculation point, m;

Attention: Formula (2) is valid when r\u003e 1..

The dependence (2) is called the Rule of "Back Squares" or the rule of "six decibels". Physical interpretation of this rule - with each doubling distance from the source, the sound level decreases by 6DB. This dependency can be submitted tables and graphically, Fig.2:

Fig.2. Sound pressure dependence on distance

Sound pressure level at the calculation point:

• N. - noise level indoors, dB (N from English. Noise - noise),
• Here - Sound pressure reserve, dB.

With zd \u003d 15DB:

If the sound pressure at the estimated point is above the level of the average noise in the room for 15 DB - the calculation is made correctly.

5. Calculation of efficient range

Efficient sound range (L) is the distance from the sound source (loudspeaker) to the geometrical location of the calculated points located within the FDN, the sound pressure in which remains within (N + 15 DB). On the technical slang - "The distance that the loudspeaker breaks.

In English literature, effective sound range (Effective Acoustical Distance (EAD)) is the distance at which the clarity and speech intelligibility (1) remains.

Calculate the difference between the sound pressure of the loudspeaker, noise level and pressure reserve.

• p. - The difference in sound pressure of the loudspeaker, noise level and pressure reserve, dB.
• 1 - The coefficient takes into account that the loudspeaker sensitivity is measured on 1m.

6. Calculation of the area voiced by one loudspeaker

The basis for estimating the magnitude of the area of \u200b\u200bthe area is the following installation:

Calculation will be carried out from the following assumptions: a loudspeaker (radiation) diagram (radiation) can be represented as a cone (sound field concentrated in a cone) with a corporal angle at the top of the cone equal to the width of the radiation chart.

The area voiced by the loudspeaker is the projection of the sound field, a limited opening angle to the plane, carried out in parallel floor at a height of 1.5m. By analogy with an effective range: The effective area voiced by the loudspeaker is the area of \u200b\u200bsound pressure within which it does not exceed N + 15 DB (F-La 5).

Note: The loudspeaker radiates in all directions, but we will rely on the input data - levels of sound pressure within the orientation diagram. The correctness of this approach is confirmed by the statistical theory.

We break loudspeakers on grade 3 (type):

1. ceiling
2. wall
3. rule.

8. Calculation of an effective area voiced by a wall loudspeaker

9. Calculation of the effective area of \u200b\u200bthe voapped ripped loudspeaker

10. Calculation of the number of loudspeakers needed to sound a certain territory

Having calculated the effective area voiced by one loudspeaker, knowing the total dimensions of the voiced territory, we will calculate the total number of loudspeakers:

• SP. - voiced area, m2,
• SGR - effective area voiced by one loudspeaker, m2,
• Int. - The result of rounding to the whole value.

11. Electroacoustic calculator

The overall result in the form of a block diagram:

Fig.6. Flowchart of an electro-acoustic calculator

Example programming

In this calculator (written in Microsoft Excel), an elementary brief technique is implemented - an electro-acoustic calculation algorithm outlined above. .

Fig.7. Electroacouser Calculator in Microsoft Excel

Based on the developed calculation algorithm, it works and.

Appendix 1. List and brief characteristics of ROXTON loudspeakers

General.

Calculation of acoustic parameters of sound-reproducing devices involves the selection of the required loudspeakers depending on the current level of background noise and the selected voice circuit. The current level of background noise depends on the purpose of the premises. It is believed that for high-quality speech perception (dispatching gear), the sound pressure level of the loudspeaker must be 10-15DB to exceed the level of background noise in the most remote room point.

With relatively low background noise (less than 75DB), it is necessary to provide an overweight level of 15 DB, with high (more than 75DB) - 15DB is enough.

Those. Required sound pressure level:

DB - for premises with a relatively low level of background noise;

, dB - for premises with a high level of background noise;

where - current level of background noise indoors

For comparison, you can bring the characteristic levels for the premises of various purposes:

normal silence indoors - 45 - 55DB;

muted conversations indoors - 55DB;

talk of students during class - 60DB;

noises in the middle store - 63DB;

noises on change in the premises of educational institutions, in large stores - 65 - 70DB;

noise in the hallways of train stations, very large stores, etc. premises with a large number of talking people - 70 - 75DB;

noises in hardware halls, etc. premises with a large number of working people and mechanisms - 75 - 80DB;

noises in the workshops of metal and woodworking enterprises, at large factories - 85 - 90DB.

Characteristics of loudspeakers.

The main characteristics of loudspeakers include their focus, frequency range and sound pressure level developing on one meter from the emitter.

Non-directional loudspeakers consider speakers, ceiling loudspeakers, as well as all sorts of sound columns (although, if you count more strictly, the column occupy an intermediate position between directional and non-directional systems). The propagation area of \u200b\u200bthe sound of non-directional loudspeakers (radiation diagram) is quite wide (about 60 °), and the sound pressure level is relatively small.

To directional loudspeakers first of all include the TSR emitters of the so-called. "Bells". In the horn loudspeakers, the concentration of acoustic energy occurs due to the design features of the horn itself, they differ in a narrow pattern of the orphanage (about 30 °) and a high level of sound pressure. High loudspeakers work in a narrow frequency band and therefore are poorly suitable for high-quality playback of musical programs, although due to the high level of sound pressure, they are well suited for voicing large areas, including open spaces.

Selection of loudspeakers by frequency range depends on the purpose of the system. For dispatching gears and creating a musical background, a range of 200Hz is 5 kHz, it is provided with practically any speaker devices (the ripped emitters have a slightly smaller range, but it is enough for speech gear). For high-quality sounding, loudspeakers are required having a frequency range of at least 100Hz - 10 kHz.

Necessary level of sound pressure it is the only characteristic of the loudspeaker, which is determined by the results of the calculations. It is with this characteristic that the greatest number of problems arises and in most commonly they are associated with the confusion between electrical power and sound pressure. Between these values, there is an indirect dependence, since the volume of the sound is determined by sound pressure, and the power ensures the operation of the loudspeaker, from the input power only part is converted into the sound and the value of this part depends on kp. Specific loudspeaker. Most of the producers of acoustic systems lead or sound pressure in Pascals (PA), or sound pressure level in dB at a distance of 1m from the emitter. If the sound pressure is given, and it is required to obtain the sound pressure in dB, the translation of one value to another is carried out by the formula:

For a typical non-directional loudspeaker, it can be assumed that 1W of electrical power corresponds to the level of sound pressure of approximately 95DB. Each increase (reduction) of the power is twice, leads to an increase (decrease) of sound pressure level by 3DB. Those. 2W - 98DB, 4W - 101 DB, 0.5W - 92DB, 0.25W - 89DB, etc. There are loudspeakers having a sound pressure on 1W power of less than 95DB and loudspeakers providing 1W 97 and even 100DB, with a monodovable loudspeaker with a sound pressure level of 100DB replaces the loudspeaker with a power of 4 W with a level of 95DB / W (95DB - 1W, 98DB - 2W, 101 DB - 4W), it is obvious that the use of such a loudspeaker is more economical. It can be added that with the same electrical power, the sound pressure level of ceiling loudspeakers by 2 - 3 dB is lower than the walls. This is due to the fact that the wall loudspeaker is located either in a separate housing, or in a well-reflective rear surface, so the sound emitted back is almost completely reflected forward. Ceiling loudspeakers, as a rule, are attached on false-volts or suspensions Therefore, the sound emitted back is not reflected and

does not affect the increase in front sound pressure. Ripped loudspeakers with 10 -30 W capacities provide sound pressure 12-16pa (115-118DB) and more having, thereby, the highest dB / W ratio.

In conclusion, we once again pay attention to the fact that when calculating loudspeakers must be paid attention to the sound pressure developed by them, and not on electrical power and only in the absence of this characteristic in the description, guided by typical dependence - 95DB / W.

Calculation of the power of loudspeakers for concentrated systems.

The calculation of the power of loudspeakers for concentrated systems is carried out in the following order:

the required sound level is determined in the remote point of the voiced room:

, dB, where - The current level of background noise indoors, 10 exploration of the required sound pressure level over the background.

, PA

where - distance from the loudspeaker to the extreme point.

If several loudspeakers are used in the concentrated system, then

where - Loudspeakers in the concentrated system.

Example:

Initial data:-- 15m;

- 65DB.

\u003d 65 + 10 \u003d 75DB;

=

\u003d 0.112pa;

\u003d 0.112 * 15 \u003d 1.68pa;

=

\u003d 98.5DB.

1W Typical Loudspeaker provides a sound pressure level of about 95dB, 2W - 98DB. The required estimated sound pressure level is 98.5 DB slightly more than 2W, therefore you can apply a two-speech loudspeaker.

Initial data: - 15m;

level of background noise indoors - - 75DB.

Required Sound Level at Remote Point -

\u003d 75 + 10 \u003d 85DB;

=

\u003d 0.35 Pa;

\u003d 0.35 * 15 / 2 \u003d 3.6pa;

=

\u003d 105DB.

1W standard loudspeaker provides a sound pressure level of approximately 95dB, 2W - 97DB, 4W - 101 DB, 8W - 104DB consequently, each of the two speakers must have a power of about 8W.

Initial data:distance from loudspeaker to remote point - 80m;

background noise level - - 70DB.

Required Sound Level at Remote Point -

\u003d 70 + 10 \u003d 80DB;

Required sound pressure at the remote point:

=

\u003d 0.19 Pa;

The necessary sound pressure at a distance of 1m from the loudspeaker:

\u003d 0.19 * 80 \u003d 15.96pa;

The sound pressure level that should develop a loudspeaker at a distance of 1M:

=

\u003d 117.6 dB.

50grd-3 type loudspeaker with 50W, has a sound pressure level of 118DB, i.e. It is sufficient to sound a section at a given distance.

To simplify the capacity calculations of standard loudspeakers for small rooms (as a rule, with a concentrated system), you can use the graphs below (Fig.4.9). The graphs are obtained for the premises, based on the ratio of the width to the length (b / l) \u003d 0.5 and the ceilings with a height of 3 - 4.5m. The dependency is somewhat more typical - 97DB / W. Above each curve is the level of background noise and in brackets, the required sound pressure level. For example, a room with an area of \u200b\u200b80m.kv., the background noise level is 72DB, the required sound pressure level of 82 dB, according to the graph - the required electrical power of the standard loudspeaker is 4 W.

Calculation of the power of loudspeakers for distributed systems

Calculation of the power of loudspeakers for the single and double wall chain:

the required level of sound in the room is determined:

, dB, where - current level of background noise indoors.

the sound pressure is calculated, which should develop a loudspeaker at a remote point:

, PA

sound pressure is determined, which should develop a loudspeaker at a distance of 1M:

for a single chain or chain, staggered

PA,

for dual chain:

, PA

where b. – width premises D.- Distance between loudspeakers in the chain. Instead D.you can substitute the expression: D.=L./ N., where L. - Length of the room , N- Number of loudspeakers along one wall.

the sound pressure level is determined, which should provide each loudspeaker:

1. Calculation of expected sound pressure levels at the calculation point and the required reduction in noise levels.

If there are several noise sources with different levels of radiated, then the sound pressure levels for medium megometric frequencies 63, 125, 250, 500, 1000, 2000, 4000 and 8000 Hz and the calculation point should be determined by the formula:

L - expected octave pressure levels at the calculation point, dB; χ is an empirical correction coefficient, taken depending on the ratio of the distance of the calculated point to the acoustic center to the maximum dimensional size of the source of 1Max, Fig.2 (Methodical instructions). The acoustic center of the noise source located on the floor is the projection of its geometric center on the horizontal plane. Since the ratio R / LMAK in all cases, then we will take

determined by table. 1 (Methodical instructions). LPI - octal sound power level of noise source, dB;

F - Formation factor; For sources with uniform radiation, F \u003d 1 is accepted; S is the area of \u200b\u200bthe imaginary surface of the correct geometric shape surrounding the source and passing through the calculation point. In the calculations, admit where R is the distance from the calculated point to the source of noise; S \u003d 2πr 2

ψ-coefficient, taking into account the violation of the diffusion of the sound field indoor, adopted according to the graphics of Fig.3 (Methodical instructions), depending on the ratio of a constant room in the area of \u200b\u200bthe enclosing room surfaces

B is a permanent room in octave frequency bands, determined by the formula, where in Table. 2 (guidelines); M is the frequency multiplier determined by table. 3 (guidelines).

For 250 Hz: μ \u003d 0.55; m 3.

For 250 Hz: μ \u003d 0.7; m 3.

For 250 Hz: ψ \u003d 0.93

For 250 Hz: ψ \u003d 0.85

t - the number of noise sources closest to the calculation point for which (*). In this case, a condition for all 5 sources is satisfied, therefore T \u003d 5.

n- Total noise sources indoor with coefficient

simultaneity of their work.

We will find the expected octave sound pressure levels for 250 Hz:

L \u003d 10LG (1x8x10 / 353.25 + 1x8x10 / 759,88 + 1x3.2x10 / 401.92 + 1x2x10 / 566.77 + 1x8x10 / 1230.88 + 4 x 0.93 x (8x10 + 8x10 +

3,2x10 + 2x10 + 8x10) / 346,5) \u003d 93,37DB

Find expected octave sound pressure levels for 500 Hz:

L \u003d 10LG (1x1.6x10 / 353.25 + 1x5x10 / 759,88 + 1x6,3x10 / 401.92 +

1x 1x10 / 566.77 + 1x1.6x10 / 1230,88 + 4 x 0.85 x (1.6x10 + 5x10 +

6.3x10 + 1x10 + 1.6x10) / 441) \u003d 95.12 dB

The required reduction in sound pressure levels at the calculation point for eight

octave stripes by the formula:

where

Required reduction of sound pressure levels, dB;

Obtained by calculation of octave levels of sound pressure, dB;

L Premissible octave sound pressure level in insulated with noise

premises, dB, table. 4 (Methodical instructions).

For 250 Hz: ΔL \u003d 93.37 - 77 \u003d 16.37 dB for500 Hz: ΔL \u003d 95.12 - 73 \u003d 22,12 dB

2. Sound-insulating fences, partitions.

Soundproofing fences, partitions are used to separate the "quiet" premises from adjacent "noisy" premises; Performed from dense, other materials. They are possible a device of doors, windows. The selection of the design material is made according to the required soundproofing ability, the value of which is determined by the formula:

-Summary octave sound power level

emitted by all sources is determined using Table. 1 (Methodical instructions).

For 250Hz: dB.

For 500 Hz:

B and - constant insulated room

In 1000 \u003d V / 10 \u003d (8x20x9) / 10 \u003d 144 m 2

For 250 Hz: μ \u003d 0.55 B and \u003d at 1000 · μ \u003d 144 · 0.55 \u003d 79.2 m 2

For 500 Hz: μ \u003d 0.7 b and \u003d at 1000 · μ \u003d 144 · 0.7 \u003d 100.8 m 2

t - the number of elements in the fence (partition with the door T \u003d 2) S i - the area of \u200b\u200bthe fence element

S Walls \u003d VHN - S Door \u003d 20 · 9 - 2.5 \u003d 177.5 m 2

For 250 Hz:

R Rev.Tenes \u003d 112.4 - 77 - 10lg79,2 + 10lg177,5 + 10lg2 \u003d 41.9

R c. DVER \u003d 112.4 - 77 - 10LG79,2 + 10LG2,5 + 10LG2 \u003d 23.4 dB

For 500 Hz:

R Rev.53 - 115.33 - 73 - 10lg100,8 + 10lg177,5 + 10lg2 \u003d 47.8 dB

R require.DVER \u003d 112.4 - 73 - 10LG100,8 + 10LG2,5 + 10LG2 \u003d 29.3 dB

Soundproofing fencing consists of doors and walls, we will select the material

constructions on table. 6 (Methodical instructions).

Door - a deaf panel door with a thickness of 40mm, lined on two sides plywood 4mm thick with sealing pads. The wall is a brick masonry thick on both sides in 1 brick.

3.3Busto-eyed facing

Used to reduce the intensity of reflected sound waves.

Sound-absorbing cladding (material, sound absorption design, etc.) should be made according to Table. 8, depending on the required noise reduction.

The magnitude of the possible maximum reduction of sound pressure levels at the calculation point when applying selected sound-absorbing structures is determined by the formula:

In the residual room before installing sound-absorbing cladding in it.

B 1 - permanent room after installation in it sound-absorbing design and is determined by the formula:

A \u003d α (S OGR - S region)) - the equivalent area of \u200b\u200bsound absorption of surfaces not occupied by sound-absorbing cladding;

α -to-across the sound absorption coefficient of surfaces not occupied by sound-absorbing lining and is determined by the formula:

For 250Hz: α \u003d 346.5 / (346,5 + 2390) \u003d 0.1266

For 500 Hz: α \u003d 441 / (441 + 2390) \u003d 0.1558

SOBL - Sound-absorbing facing area

Singles \u003d 0.6 S OGR \u003d 0.6 x 2390 \u003d 1434 m 2 for 250 Hz: a 1 \u003d 0.1266 (2390 - 1434) \u003d 121.03 m 2 for 500 Hz: a 1 \u003d 0.1558 (2390 - 1434) \u003d 148.945 m 2

ΔA is the value of the added sound absorption introduced by the design of the sound-absorbing cladding, M 2 is determined by the formula:

Reverb coefficient of sound absorption of the selected cladding design in the octave frequency band, defined by Table 8 (guidelines). Choose super-thin fiber,

ΔA \u003d 1 x 1434 \u003d 1434 m 2

constructions defined by the formula:

For 250 Hz: \u003d (121.03 + 1434) / 2390 \u003d 0,6506;

In 1 \u003d (121.03 + 1434) / (1 - 0,6506) \u003d 4450.57 m 2

ΔL \u003d 10LG (4450.57 x 0.93 / 346.5 x 0.36) \u003d 15.21 dB. "

For 500 Hz: \u003d (148.945 + 1434) / 2390 \u003d 0.6623;

In 1 \u003d (148.945 + 1434) / (1 - 0.6623) \u003d 4687.43 m 2

ΔL \u003d 10LG (4687.43 x 0.85 / 441 x 0.35) \u003d 14.12 dB.

For 250 Hz and 500 Hz, the selected sound-absorbing cladding will not provide the necessary reduction in noise in octave frequency bands as:

Dano: in the work room with a length A M, width in m, and the height of n m
There are sources of noise - ISH1, ISH2, ISH3, IS4 and ISH5 with sound power levels. Source Noise Ish1 is enclosed in the casing. At the end of the workshop is the premises of auxiliary services, which is separated from the main workshop by a partition with a door area. The calculation point is located at a distance of noise sources.

4. Levels of sound pressure at the calculation point - RT, compare with valid norms, determine the required reduction in noise at workplaces.

5. The soundproofing ability of the partition and the door in it, choose the material for the partition and the door.

6. The soundproofing ability of the housing for the source of ISH1. The nozzle is mounted on the floor, its dimensions in terms of - (a x b) m, height - H m.

4. Reducing noise when installing on the site of the sound-absorbing cladding plant. Acoustic calculations are carried out in two octave bands on medium meterometric frequencies 250 and 500Hz.

Initial data:

Good day.

We have already said that the requirements for SOUE (system alert and management systems) are governed by Tom SP 3.13130.2009. "Set of rules. Fire protection systems. The system of alert and management of the evacuation of people in a fire. Fire safety requirements. "

The main requirement for sound systems - they must provide a minimum level of sound pressure at the level of 1.5 m from the floor (i.e. at the height of the ears of the average person) 15 dB above the average noise level in the room, but not at least 75 dB. At the same time, the maximum sound pressure level created by the SOOR should not exceed 120 dB: this is a pain threshold, then it is still useless - only harm can be applied. Therefore, if the noise level is on the facility, say, 110 dB, then your Sowe should be tested not quieter and not louder 120 dB, and an increase in efficiency should be achieved by all sorts of light effects - stroboscopes for example. In bedrooms, hotels, hospital wards, etc. The sound level is measured at the height of the head of the sleeping person.

Options for placing sound sources. It is possible to add in the corner of the Hall of the Rupor Loudspeaker type "Bell" of nightmare power and let it yell "on the whole forest." As a result, at the far end of the room, the sound will satisfy the requirements, and people will sall near the sound source. So I forgot to add: "Code of Rules" requires even evenly distribution of sound (clause 4.7. Installing loudspeakers and other speech bugs in protected areas should exclude a concentration and uneven distribution of reflected sound.).

Therefore, ceiling speakers are widely used in large rooms - they allow you to create just that the most uniform distribution of sound pressure. There are many designs for mounting into suspended ceilings, there are suspended speakers, externally similar to the chandeliers.

In the corridors and small rooms, wall speakers are quite suitable, their placement is toughly regulated: not lower than 2.3 m from the floor, but at least 15 cm from the ceiling. There is, by the way, bidirectional loudspeakers: in the middle of the corridor, he was granted on the wall, he says there.

It is necessary to add that, in order to avoid large power losses on wires, the amplifiers produce a high-voltage signal, 100-120 V. speakers are equipped with low transformers.

On the calculation of Ceiling speakers:

The number of ceiling speakers for visiting the room is calculated without taking into account the power - net geometry. We believe that the dynamics pattern diagram is equal to 90 degrees, it is necessary that they are evenly, the premises at an altitude of 1.5 m from the floor voiced. Those who wish can make me lazy, so without any details:

b. ering the height of the room minus 1, 5m, proudly call the resulting number "H". Speakers hang apart from each other at a distance of 2H, from the wall - h.

The area, which is voiced by one ceiling speaker approximately:

Now we take the area of \u200b\u200bthe room and divide on this S (OP), get the number of speakers. For example, we have a hefty warehouse 7000 sq.m, height 6m. In this case, H \u003d 6m-1,5m \u003d 4.5m. S (OP) is obtained by approximately 2x4.5x2x4.5 \u003d 81 square meters. m. The number of speakers:

N \u003d 7000: 81 \u003d 86

Now about power. Any normal speaker (loudspeaker) among the technical characteristics has such an interesting parameter as the sensitivity measured in W / m. True, then, for the convenience of calculations, it is translated into dB, who want to search for themselves how to translate watts to Decibel, this is already the theory, do not want to break down into details. In short, sensitivity is a sound pressure that creates a speaker at a distance of 1 m with a power dissipation on it 1 W.

We have to create a sound pressure more by 15 dB than noise level indoors. In order not to run with a sound meter, we use the sign of the sample levels of noise in the rooms:

Since we have a warehouse, take the noise level of 70 dB. Take the LPA-6 speaker from Luis Plus, it has a sensitivity of 94 dB, i.e. With the power of 1 W at a distance of 1 m from it, it creates a sound pressure \u003d 94 dB. We need 4.5 m at a distance (our distance "H") to get soundproof

70DB + 15DB \u003d 85DB

We use the chart of attenuations of sound pressure C depending on the removal from the dynamics provided by the same company Luis Plus:

At a distance of 1 m attenuation \u003d 0, and on the 4.5 m we need is about 13 dB. Those. From the source 94 dB (the sensitivity of the dynamics or sound pressure at a distance of 1 m), we need to subtract 13 dB. We obtain that with the power of 1 W, our speaker shakes us at the level of 1.5 m from the floor press 81 dB. And it is necessary to 85 dB.

Let's look at the characteristics of our dynamics:

See, in the inclusion power column costs 3 connection options: 6 W, 3 W and 1.5 W. Those. There are several taps on its converter to it that allow, at a voltage on a transformer 100 V, to develop the power of 6 W, 3 W or 1.5 W.

And, for complete happiness, another plate is a strengthening of dB depending on the dynamics of power:

We need to dig 85 dB at a distance of "H" from the speaker. We received the estimated 81 dB, i.e. You need to add 4 dB. We look - with the power of 3 W, the amplification of sound pressure will be 4.8 dB, which means and connect the speaker to the power of 3 W, we will have 85DB with some reserve.

Multiply the power of the dynamics to their number and get the minimum sufficient power of the amplifier. In our case, it is 3W x 86 \u003d 258 W.

In general, quite confused first, but let's briefly repeat.

1. Not tied to any facilities, stupidly based on geometry, we consider the area that one speaker must sound at a given room altitude. Then, based on the area of \u200b\u200bthe room, we consider the number of speakers.
2. We choose speaker and, based on its sensitivity, we believe what sound pressure it can create at a height of 1, 5m from the floor with a capacity of 1 W
3. Well, finally, we believe what power it is necessary to develop on the dynamics to get the sound pressure we need on the most magical height of 1.5 m. Of course, if this power will be higher than the limit power of the dynamics, you will have to pick another model.

Well, in general, and all the horrors. From the second approach is not so scary.

But the very first formula:

i recommend remembering by heart, the good is simple. Imagine you inspect the object, the customer asks how much an alert will cost. With this formula, you can calculate the number of ceiling speakers on your fingers, adding the cost of amplifiers and cables to them, indicate at least the scale scale. The customer like such efficiency.

Questions - in "Camments" or by mail [Email Protected], Form subscription to news - downstairs.

One of the main tasks solved in the process of electroacoustic calculation, performed at the initial stage of designing fire alert systems - SOUE is the task of choosing and aligning speech alarms (hereinafter loudspeakers). Loudspeakers can be installed both on open areas, so in closed (protected) rooms. The purpose of this article is to propose and substantiate the options for the optimal alignment of speech alarms (hereinafter loudspeakers) in closed (protected) premises.

In the closed rooms, it is recommended to install internal execution loudspeakers as the most optimal parameters and quality. Depending on the configuration of the room, it can be ceiling or wall types. The competent arrangement of loudspeakers allows you to ensure a uniform distribution of sound in the room, therefore, achieve good intelligibility. If we talk about the quality of sound, it will be determined mainly by the quality of selected loudspeakers. For example, when using ceiling loudspeakers, it is necessary to take into account that the sound wave from the loudspeaker is distributed perpendicular to the floor, therefore, the voiced area at the height of the ears of the listeners is a circle, the radius of which is taken equal to the height difference (fastening) of the loudspeaker and the distance to 1.5 m from the floor (according to regulatory documentation). In most tasks for calculating the ceiling acoustics, the sound waves are identified with the geometric rays, with the directional pattern (DN) of the loudspeaker determines the parameters (angles) of the rectangular triangle, therefore, to calculate the radius of the circle (triangle category), the Pytagora theorem is sufficient. For uniform sounding of the room, loudspeakers should be installed so that the resulting areas come into contact or slightly overlap each other. In the simplest case, the required number of loudspeakers is obtained from the ratio of the values \u200b\u200bof the voiced area to the square, voiced by one loudspeaker.

One of the main parameters to be determined in the calculations is the loudspeaker chain arrangement. It will be determined by the size of the room, the height of the setting of loudspeakers and their radiation diagram (IDN).

When setting up wall loudspeakers in the corridors along one wall, the recommended setting step:

excluding reflections from the walls:

(Setting step, m) \u003d (width of the corridor, m) x 2

• taking into account the reflections from the walls:

  (Pitch of the arrangement, m) \u003d (width of the corridor, m) x 4

When setting up wall loudspeakers in rectangular premises on the two walls in a checker order, the setting step:

With the oncoming alignment of wall loudspeakers in rectangular premises on two walls of the arrangement step:

Primary requirements

We present the basic requirement of regulatory documentation (ND):

The number of sound and speech (loudspeakers) of fire alarms, their arrangement and power should provide sound level in all places of permanent or temporary stay of people in accordance with the norms of this Code of Rules.

The design of the alert systems is accompanied by the implementation of the electroacoustic calculation (EAR). The consequence of the competent EAR is optimization - minimization of technical means, improving the quality of perception. The quality of perception, in turn, is characterized by the comfort of sound for the musical background and intelligibility for speech messages. The criterion for the correctness of EAR is the requirements of regulatory documentation (ND), which can be divided into:

• requirements for the speech and wrister (loudspeaker);

  requirements for sound signals;

  requirements for the alignment of speech alarms (loudspeakers).

It should be noted that only the necessary (minimum) requirements are set out in the ND while sufficient (maximum) requirements are provided by the presence of competent techniques, and in their absence, the designer literacy and responsibility.

Requirements for loudspeaker

The following requirements are set out. Sound bells must provide sound pressure level so that:

SUE sound signals provided the overall sound level (the sound level of constant noise, together with all signals produced by the alarms) at least 75 dBs at a distance of 3 m from the bunch, but not more than 120 dBA at any point of the protected room.

This paragraph contains two requirements - the requirement for minimal and maximum sound pressure.

Minimal audio pressure

The loudspeaker must provide (minimal) sound signal level at a distance of 1M from the geometric center:

Maximum sound pressure

Let's give the definition of the calculation point:

The calculated point (RT) is the place of possible (probable) finding people most critical from the point of view of the position and deletion from the audio source (loudspeaker). The RT is selected on the calculated plane - (imaginary) plane, carried out parallel to the floor at an altitude of 1.5 m.

Requirement of sound signals

The main requirement for the (necessary) level of the sound signal is set out in ND:

SOUN Sound signals should provide a sound level of at least 15 dba above the permissible sound level of constant noise in the protective room. Measuring the sound level should be carried out at a distance of 1.5 m from the floor level.

Requirements for the arrangement

The main requirement for the arrangement of loudspeakers is set out in ND:

Installing loudspeakers and other speech bugs (loudspeakers) in protected premises should exclude a concentration and uneven distribution of reflected sound.

Speech alarms (loudspeakers) should be located in such a way that anywhere in the protected object, where the alert of people about the fire is required, the intelligibility of the transmitted voice information was provided.

Accounting for the main characteristics of loudspeakers

According to the arrangement of loudspeakers is part of organizational measures performed in the design of SOUE and called an electro-acoustic calculation. The most relevant is not just an arrangement, but the optimal arrangement of loudspeakers, which allows minimizing the number of settlement resources (time) and material means.

Methods for the arrangement of loudspeakers are closely related to their constructive features. The most generalized is the following classification:

by execution;

according to constructive features;

according to the characteristics;

according to the method of coordination with the amplifier.

Accounting type and design features of loudspeakers

By execution, loudspeakers can be divided into internal and external. The characteristic feature of the internal execution is the IP protection class. For internal execution loudspeakers, IP-41 is sufficient, for external - not lower IP-54. For premises, first of all, in order to save, the loudspeakers of internal execution are used.

Depending on the tasks, there may be loudspeakers of various structural execution. For example, depending on the configuration of the room can be used the loudspeakers of the ceiling or wall design. For sounding open areas, ripped loudspeakers are used, due to their characteristics, protection class, high degree of sound orientation, high efficiency.

Specifications of the main parameters of loudspeakers

To implement the competent arrangement of loudspeakers, we need the following characteristics (basic parameters) of the loudspeaker:

Loudspeaker Sound Pressure Calculation

The loudspeaker volume cannot be measured directly, therefore it is expressed in practice through sound pressure levels measured in decibels, dB.

The sound pressure of the loudspeaker is defined by both its sensitivity and electrical power supplied to its input:

Sensitivity of the loudspeaker P 0, dB (loudspeaker sensitivity is sometimes called SPL from English. SPL - Sound Pressure Level) - sound pressure level measured on the operating axis of the loudspeaker, at a distance of 1 m from the work center at 1 kHz at 1W power.

Power loudspeaker

There are several main types of capacity:

Rated power of the loudspeaker - Electrical power at which non-linear distortion of the loudspeaker does not exceed the required values.

Passport power loudspeaker - It is defined as the highest electrical power at which the loudspeaker can continue to work satisfactorily on the real sound signal without thermal and mechanical damage.

Sinusoidal power - The maximum sinusoidal power at which the loudspeaker should work for 1 hour with a real musical signal without obtaining physical damage (CP. Maximum sinusoidal power).

In the general case, as a power parameter, it is necessary to use the value specified by the loudspeaker manufacturer.

The audio pressure of the loudspeaker is recommended to calculate depending on the power of the loudspeaker.

Main calculations

Reducing sound pressure depending on distance

To calculate the level of sound pressure at the calculation point, another important parameter remains - the value of the reduction of sound pressure depending on the distance - divergence, P 20, dB. Depending on where the loudspeaker is established - various formulas (approaches) are used in interior or open venues.

Calculation of sound pressure in the RT

Knowing the loudspeaker parameters - its sensitivity - P 0, dB, the resulting sound power P W, W, and the distance to the RT, R, M, calculate the sound pressure level L 1, dB developed by him in the Republic of Tajikistan:

Sound pressure in the RT with simultaneous operation of n loudspeakers:

Calculation of efficient range

The effective sound of the loudspeaker is the distance from the loudspeaker to the point in which the sound pressure does not exceed the values \u200b\u200b(ears + 15) dB:

Effective sound range (loudspeaker) D, M, can be calculated: