The unit of the absolute loudness scale is background. The loudness of 1 phon is the loudness of a continuous pure sinusoidal tone with a frequency of 1 kHz, producing a sound pressure of 2 MPa.
Sound volume level - relative value. It is expressed in backgrounds and numerically equal to the sound pressure level (in decibels - dB) created by a sinusoidal tone with a frequency of 1 kHz of the same loudness as the measured sound (equally loud to this sound).
Dependence of volume level on sound pressure and frequency
The figure on the right shows a family of equal loudness curves, also called isophones. They are graphs of standardized (international standard ISO 226) dependences of sound pressure level on frequency at a given volume level. Using this diagram, you can determine the volume level of a pure tone of any frequency, knowing the level of sound pressure it creates.
Sound surveillance equipment
For example, if a sinusoidal wave with a frequency of 100 Hz creates a sound pressure level of 60 dB, then by drawing straight lines corresponding to these values in the diagram, we find an isophone at their intersection, corresponding to a volume level of 50 phon. This means that this sound has a volume level of 50 phon.
The isophone "0 background", indicated by a dotted line, characterizes hearing threshold sounds of different frequencies for normal hearing.
In practice, it is often not the loudness level expressed in phons that is of interest, but the value showing how much a given sound is louder than another. Of interest is also the question of how the volumes of two different tones add up. So, if there are two tones of different frequencies with a level of 70 phon each, this does not mean that the total volume level will be equal to 140 phon.
The dependence of loudness on the sound pressure level (and sound intensity) is a purely non-linear curve, it has a logarithmic character. When the sound pressure level is increased by 10 dB, the sound volume will increase by 2 times. This means that volume levels of 40, 50, and 60 phon correspond to volumes of 1, 2, and 4 sons.
| Sound | Volume, sleeps: |
Volume level, backgrounds: |
|---|---|---|
| hearing threshold | 0 | 0 |
| Tick wrist watch | ~ 0.02 | 10 |
| Whisper | ~ 0.15 | 20 |
| Sound wall clock | ~ 0.4 | 30 |
| Muted conversation | ~ 1 | 40 |
| Quiet street | ~ 2 | 50 |
| normal conversation | ~ 4 | 60 |
| noisy street | ~ 8 | 70 |
| health risk level | ~ 10 | 75 |
| Pneumatic hammer | ~ 32 | 90 |
| blacksmith shop | ~ 64 | 100 |
| Loud music | ~ 128 | 110 |
| pain threshold | ~ 256 | 120 |
| Siren | ~ 512 | 130 |
| Reactive plane | ~ 2048 | 150 |
| death level | ~ 16384 | 180 |
| Noise weapon | ~ 65536 | 200 |
Notes
Wikimedia Foundation. 2010 .
See what "Sound volume" is in other dictionaries:
A value that characterizes the auditory sensation for a given sound. G. h. in a complex way depends on the sound pressure (or sound intensity), frequency and mode of vibration. At a constant frequency and shape of vibrations G. z. increases with increasing sound. ... ... Physical Encyclopedia
The magnitude of the auditory sensation, depending on the intensity of the sound and its frequency. At a constant frequency, the volume of the sound increases with increasing intensity. With the same intensity, sounds in the frequency range 700 6000 ... ... have the highest volume. Big Encyclopedic Dictionary
sound volume- The magnitude of the auditory sensation, depending on the intensity of the sound and its frequency [Terminological dictionary for construction in 12 languages (VNIIIS Gosstroy of the USSR)] Topics noise, sound EN sound loudnesssound volume DE Lautstärke FR intensité de sonvolume… … Technical Translator's Handbook
The magnitude of the auditory sensation, depending on the intensity of the sound and its frequency. At a constant frequency, the volume of the sound increases with increasing intensity. At the same intensity, sounds in the frequency range 700 ... ... have the highest volume. encyclopedic Dictionary
A measure of the strength of the auditory sensation produced by a sound. G. h. depends on the effective sound pressure and sound frequency (see Fig.). For comparison G. z. use the value of LN, to paradise called. G.'s level z. and is equal to: LN \u003d 20 lg (p * eff / p * 0), where p * 0 \u003d 20 ... ... Big encyclopedic polytechnic dictionary
sound volume- garsumas statusas T sritis radioelektronika atitikmenys: angl. volume of sound vok. Lautheit, f; Lautstarke, f; Tonstarke, f rus. sound volume, f pranc. volume sonore, m … Radioelectronics terminų žodynas
A value that characterizes the auditory sensation for a given sound. G. h. depends in a complex way on sound pressure (See sound pressure) (or sound intensity (See sound intensity)), frequency, and mode shape. With the same... ... Great Soviet Encyclopedia
sound volume- rus intensity (g) (strength) of sound, loudness (g) of sound eng sound intensity fra intensité (f) acoustique, intensité (f) sonore, intensité (f) du son deu Schallintensität (f), Schallstärke (f) spa intensidad (f) sonora, intensidad (f) acoustica... Occupational safety and health. Translation into English, French, German, Spanish
The magnitude of the auditory sensation, depending on the intensity of the sound and its frequency. At a constant frequency G. h. grows with increasing intensity. At the same intensity, max. sounds in the frequency range of 700-6000 Hz have loudness. Zero… … Natural science. encyclopedic Dictionary
The magnitude of the auditory sensation, depending on the intensity of the sound and its frequency (Bulgarian; Bulgarian) sound strength (Czech; Čeština) hlasitost zvuku (German; Deutsch) Lautstärke (Hungarian; Magyar) hangosság (Mongolian ... ... Construction dictionary
Books
- A set of tables. Physics. mechanical waves. Acoustics (8 tables) , . Educational album of 8 sheets. Article - 5-8665-008. wave process. longitudinal waves. transverse waves. Periodic waves. Reflection of waves. standing waves. Sound waves. Sound pitch...
Sound power is a value measured by the amount of energy flowing every second through an area of \u200b\u200b1 cm 2, perpendicular to the direction of the sound wave.
The strength of sound is measured in erg / cm 2 · sec or in j / m 2 sec.
The intensity of sound corresponds to the sensation of loudness, just as the frequency of vibration corresponds to the pitch..
The power of sound and loudness are not equivalent concepts. The strength of the sound characterizes the physical process, regardless of whether it is perceived by the listener or not, while the loudness is the subjective quality of the sound.
Let us now consider what determines the strength of sound, and consequently, its loudness. Let's write down for this vibrations of a tuning fork consecutively several times with some intervals in time. The sound of the tuning fork gradually subsides, and this is immediately reflected in the graph of its oscillations.
As can be seen from graphs 1, 2, 3, the period of oscillation of the tuning fork did not change: the ridges and troughs on all three graphs are equally frequent. But as the sound weakened, the amplitude of the oscillations decreased. The strongest sound had the largest amplitude (plot 1); when the sound became almost inaudible, the oscillation amplitude turned out to be small (graph 3). When the tuning fork stops oscillating, the graph will turn into a straight line.
Thus, we see that the strength of the sound is related to the amplitude of the vibrations.
The larger the vibration amplitude, the stronger the sound, the smaller the amplitude, the weaker the sound..
When a body sounds, it vibrates the surrounding particles of the medium (for example, air particles) and gives them part of its energy. The energy reserve in the sounding body decreases, the amplitude of its oscillations decreases, the sound weakens.
When propagating through a medium, sound weakens as it moves away from the source. All the energy that was at first concentrated around one center - the source of sound, as it moves away from it, will be distributed to more and more more medium particles; each particle will have less and less energy. When sound waves propagate in an isotropic medium, the surface of the propagating wave will be a sphere with center O, which practically coincides with the sound source. The surface of the sphere will increase in proportion to the square of the distance from the source. The energy per unit area of the sphere's surface will vary inversely with the square of the distance from the sound source. Hence, the strength of the sound varies inversely with the square of the distance from the sound source. At the same time, the sensation of loudness associated with this value also changes, which everyone knows from experience.
If you direct sound along a pipe with the same cross section, then in this case the propagating sound almost does not lose its strength. A small attenuation of sound with distance can also be observed in long narrow corridors.
Often, cone-shaped pipes - horns - are used for negotiations at a distance. The horn does not allow sound waves to scatter in all directions and forces them to go in one direction. A horn can also be used to collect scattered sound waves. Let us put the horn to the ear with its narrow side, and the sounds will intensify. The ear is affected by all the energy that has come to the outer, wide side of the horn. How many times the outer opening of the horn is larger in area than the opening of the ear, the sound will be amplified by that many times.
Our ear is equipped with its own mouthpiece - the auricle. Sometimes, in order to pick up weak sounds, we increase this horn by putting our hand to the ear.
The human ear has exceptional sensitivity: it picks up sounds that are a million times weaker than a human voice at normal volume. On the other hand, a person gets used to enduring such strong sounds as artillery cannonade.
However, our ear turns out to be unequally sensitive to sounds of different frequencies: it is most sensitive to tones lying in the range of 1000–3000 Hz. In order for the sound to be heard in conditions of greatest sensitivity (about 2000 Hz), sound waves, as modern measurements show, must bring to the ear for every second an energy of at least 5 trillionths of an erg. The amplitude of oscillations of air particles in this case turns out to be less than one ten-billionth of a millimeter. Interestingly, the sensitivity of the eye to the energy of light is of the same order as the sensitivity of the ear to the energy of sound.
Many sometimes had to think about what exactly the power means, in one form or another given in the passports acoustic systems and sound amplifying equipment. There are surprisingly few materials on this topic on the net and in printed publications, as well as intelligible answers to questions. I'll try to somehow reduce the number of white spots in this area. Some more precise descriptions of definitions arose in my dialogue, when trying to better explain their meaning to the interlocutor.
The variety of standards used to measure the output power of amplifiers and speaker power can confuse anyone. Here is a block amplifier from a reputable company with 35 watts per channel, but here is a cheap music center with a 1000 watt sticker. Such a comparison will cause obvious bewilderment in a potential buyer. It's time for the standards...
Foreign and international standards and definitions
SPL(Sound Pressure Level) is the sound pressure level developed by the speakers. SPL is the product of the relative sensitivity of the speakers (acoustic system) to the input electrical power.
It should be borne in mind that hearing is a non-linear tool, and in order to assess subjective loudness, corrections should be made for equal audibility curves (weighting curve), which in practice differ not only for different signal levels, but also for each individual separately.
A-weighting(weighting curve) is a weighting curve.
A relationship describing sound pressure levels at different frequencies that are perceived by the ear as equally loud. Frequency response of a weighting filter used in sound pressure level measurements and taking into account the frequency properties of human hearing.
RMS(Root Mean Squared) is the rms value of the electrical power limited by the given harmonic distortions.
Or in other words - the maximum (limiting) sinusoidal power - the power at which an amplifier or speaker can work for one hour with a real music signal without physical damage. Usually 20-25 percent higher than DIN.
Power is measured with a 1 kHz sine wave when 10% THD is reached. It is calculated as the product of rms voltage and current with an equivalent amount of heat generated by direct current.
For a sinusoidal signal, the root mean square value is less than the amplitude value by V2 times (x 0.707). In general, this is a virtual value, the term "rms", strictly speaking, can be applied to voltage or current, but not to power. A well-known analogue is the effective value (everyone knows it for the AC power supply network - these are the same 220 V for Russia).
I will try to explain why this concept is for description sound characteristics uninformative. RMS power is the work done. That is, it makes sense in electrical engineering. And it does not necessarily apply to a sinusoid. In the case of musical signals, we hear loud sounds better than weak ones. And the hearing organs are affected more by amplitude values, and not by RMS.
That is, loudness is not equivalent to power. Therefore, RMS values make sense in an electric meter, but amplitude values in music. An even more populist example is the frequency response. Frequency response dips are less noticeable than peaks. That is, loud sounds are more informative than quiet ones, and the average value will say little.
Thus, the RMS standard was one attempt to describe the electrical parameters of audio equipment as a consumer of electricity.
In amplifiers and acoustics, this parameter also, in fact, has a very limited use - an amplifier that produces 10% distortion not at maximum power (when clipping occurs - limiting the amplitude of the amplified signal with specific dynamic distortions), still search.
Until the maximum power is reached, the distortions of transistor amplifiers, for example, often do not exceed hundredths of a percent, and already increase sharply above (abnormal mode). Many acoustic systems are already capable of failing during long-term operation with such a level of distortion.
For very cheap equipment, another value is indicated - PMPO, a completely meaningless and not standardized parameter by anyone, which means that Chinese friends measure it the way God puts it on their souls. To be more precise, in parrots, and each in his own. PMPO values often exceed the nominal values up to a factor of 20.
PMPO(Peak Music Power Output) is the peak short-term musical power, a value that means the maximum achievable peak value of the signal, regardless of distortion in general, for a minimum period of time (usually over 10 mS, but, in general, not normalized), the power that a speaker speaker can withstand for 1-2 seconds on a low frequency signal (about 200 Hz) without physical damage.
Usually 10-20 times higher than DIN.
As the description suggests, the parameter is even more virtual and meaningless in practical application. I advise you not to take these values seriously and not to focus on them. If you are lucky enough to buy equipment with power parameters indicated only as PMPO, then the only advice is to listen to yourself and determine whether it suits you or not.
100 W (PMPO) = 2 x 3 W (DIN)
DIN is an abbreviation for Deutsches Institut für Normung.
German non-governmental organization dedicated to standardization for better integration of the market for goods and services in Germany and the international market. The products of this organization are a wide variety of standards relating to a wide variety of applications, including those related to the field of sound reproduction, which are of interest to us here.
DIN 45500, which describes the requirements for high fidelity sound equipment (otherwise Hi-Fi - High Fidelity), includes:
- DIN 45500-1 High fidelity audio equipment and systems; minimum performance requirements.
- DIN 45500-10 High fidelity audio equipment and systems; minimum performance requirements for headphones.
- DIN 45500-2 Hi-Fi technics; requirements for tuner equipments.
- DIN 45500-3 Hi-Fi technics; requirements for disk record reproducing equipments.
- DIN 45500-4 High fidelity audio equipment and systems; minimum performance requirements for magnetic recording and reproducing equipment.
- DIN 45500-5 High fidelity audio equipment and systems; minimum performance requirements for microphones.
- DIN 45500-6 High fidelity audio equipment and systems; minimum performance requirements for amplifiers.
- DIN 45500-7 Hi-Fi-technics; requirements for loudspeakers.
- DIN 45500-8 Hi-Fi technics; requirements for sets and systems.
DIN POWER- the value of the power output on a real load (for an amplifier) or input (to the speaker) power, limited by the specified non-linear distortions. It is measured by applying a signal with a frequency of 1 kHz to the input of the device for 10 minutes. Power is measured when it reaches 1% THD (harmonic distortion).
There are other types of measurements, for example, DIN MUSIC POWER, which describes the power of a musical (noise) signal. Usually, the reported value of DIN music is higher than that given as DIN. Approximately corresponds to sinusoidal power, the power at which an amplifier or speaker can operate for long periods of time with a "pink noise" signal without physical damage.
Domestic standards
In Russia, two power parameters are used - nominal and sinusoidal. This is reflected in the names of the acoustic systems and the designations of the speakers. Moreover, if earlier the rated power was mainly used, now more often it is sinusoidal. For example, the 35AC speakers were subsequently designated S-90 (35W nominal power, 90W sine wave power)
Rated power(GOST 23262-88) is an artificial value, it leaves the freedom of choice to the manufacturer. The developer is free to indicate the value of the rated power corresponding to the most favorable value of non-linear distortion.
Usually, the specified power was adjusted to the requirements of GOST for the class of complexity of execution with the best combination of measured characteristics. It is indicated for both speakers and amplifiers. Sometimes this led to paradoxes - with “step” type distortions that occur in class AB amplifiers at low volume levels, the level of distortion could decrease when the signal output power was increased to the nominal one.
In this way, record-breaking nominal characteristics were achieved in the passports of amplifiers, with an extremely low level of distortion at a high nominal power of the amplifier. Whereas the highest statistical density of the musical signal lies in the amplitude range of 5-15% of the maximum power of the amplifier.
This is probably why Russian amplifiers were noticeably inferior to Western ones, which could have the optimum distortion at medium volume levels, while in the USSR there was a race for a minimum of harmonic and sometimes intermodulation distortion at any cost at one, nominal (almost maximum) power level.
Passport noise power- this is the electrical power limited solely by thermal and mechanical damage (for example: slipping of the voice coil turns due to overheating, burnout of conductors at kinks or solder points, breakage of flexible wires, etc.) when pink noise is applied through the corrective circuit for 100 hours.
Sinusoidal power- the power at which an amplifier or speaker can operate for a long time with a real music signal without physical damage.
Usually 2-3 times higher than the nominal value.
Maximum short-term power is the electrical power that the loudspeakers can withstand without damage (verified by the absence of chatter) for a short period of time.
Pink noise is used as the test signal. The signal is sent to the AC for 2 seconds. The tests are carried out 60 times with an interval of 1 minute. This type power makes it possible to judge short-term overloads that the speaker loudspeaker can withstand in situations that arise during operation.
Maximum continuous power is the electrical power that the loudspeakers can withstand without damage for 1 minute.
The tests are repeated 10 times with an interval of 2 minutes. The test signal is the same.
The maximum long-term power is determined by the violation of the thermal strength of the AC loudspeakers (slip of the voice coil turns, etc.).
pink noise(used in these tests) - a group of signals with a random character and uniform spectral density frequency distribution, decreasing with increasing frequency with a roll-off of 3 dB per octave over the entire measurement range, with a dependence of the average level on frequency in the form of 1/f.
Pink noise has a constant (in time) energy in any part of the frequency band.
White noise is a group of signals with a random character and a uniform and constant spectral density of frequency distribution.
White noise has the same energy in any of the frequency sections.
Octave is a musical frequency band whose extreme frequency ratio is 2.
Electric power is the power dissipated by an ohmic equivalent resistance equal in magnitude to the nominal electrical resistance of the AC, at a voltage equal to the voltage at the AC terminals.
That is, on a resistance that emulates a real load under the same conditions.
Don't forget about speaker impedance. Mostly on the market there are speakers with a resistance of 4, 6, 8 ohms, less common are 2 and 16 ohms. The power of the amplifier will vary when you connect speakers of different impedance.
The instructions for the amplifier usually indicate what speaker impedance it is designed for, or power for various speaker impedances. If the amplifier allows operation with speakers of different impedance, then its power increases with decreasing resistance.
If you use speakers with a resistance lower than that specified for the amplifier, this may cause it to overheat and fail, if higher, then the specified output power will not be achieved. Of course, the volume of acoustics is affected not only by the output power of the amplifier, but also by the sensitivity of the speakers, but more on that next time.
The main thing is not to forget that power is only one of the parameters, far from the most important for getting good sound.
Power
Under the word power in colloquial speech, many mean "power", "strength". Therefore, it is only natural that consumers associate power with loudness: “The more power, the better and louder the speakers will sound.” However, this popular belief is fundamentally wrong! It is far from always that a 100 W speaker will play louder or better than the one that has “only” 50 W power. The power value, rather, speaks not about the volume, but about the mechanical reliability of the acoustics. The same 50 or 100 watts is not loud at all published by the column. Dynamic heads themselves have low efficiency and convert only 2-3% of the power of the electrical signal supplied to them into sound vibrations (fortunately, the volume of the emitted sound is quite enough to create sound accompaniment). The value indicated by the manufacturer in the passport of the speaker or the system as a whole only indicates that when a signal of the specified power is applied, the dynamic head or speaker system will not fail (due to critical heating and interturn short circuit of the wire, “biting” of the coil frame, rupture of the diffuser , damage to flexible hangers of the system, etc.).
Thus, the power of the speaker system is a technical parameter, the value of which is not directly related to the loudness of the acoustics, although it is associated with some dependence. The nominal power values of dynamic heads, amplifying path, acoustic system can be different. They are indicated, rather, for orientation and optimal pairing between the components. For example, an amplifier of much less or much more power can disable the speaker in the maximum positions of the volume control on both amplifiers: on the first - due to the high level of distortion, on the second - due to the abnormal operation of the speaker.
Power can be measured different ways and under various test conditions. There are generally accepted standards for these measurements. Let us consider in more detail some of them, which are most often used in the characteristics of products of Western firms:
RMS (Rated Maximum Sinusoidal power- installed maximum sinusoidal power). Power is measured by applying a sinusoidal signal with a frequency of 1000 Hz until a certain level of non-linear distortion is reached. Usually in the passport for the product it is written like this: 15 W (RMS). This value says that the speaker system, when a 15 W signal is applied to it, can work for a long time without mechanical damage to the dynamic heads. For multimedia acoustics, higher power values in W (RMS) compared to Hi-Fi speakers are obtained due to measurements at very high harmonic distortions, often up to 10%. With such distortions, it is almost impossible to listen to the soundtrack due to strong wheezing and overtones in the dynamic head and speaker cabinet.
PMPO(Peak Music Power Output Peak Music Power). In this case, the power is measured by applying a short-term sinusoidal signal with a duration of less than 1 second and a frequency below 250 Hz (typically 100 Hz). This does not take into account the level of non-linear distortion. For example, the speaker power is 500 W (PMPO). This fact indicates that the speaker system, after reproducing a short-term low-frequency signal, did not have mechanical damage to the dynamic heads. Popularly, the units of power measurement W (PMPO) are called “Chinese watts” due to the fact that power values with this measurement technique reach thousands of watts! Imagine - active speakers for a computer consume 10 V * A electrical power from the AC mains and develop at the same time a peak musical power of 1500 W (PMPO).
Along with Western standards, there are also Soviet standards for different kinds power. They are regulated by the current GOST 16122-87 and GOST 23262-88. These standards define concepts such as rated, maximum noise, maximum sinusoidal, maximum long-term, maximum short-term power. Some of them are indicated in the passport for Soviet (and post-Soviet) equipment. Naturally, these standards are not used in world practice, so we will not dwell on them.
We draw conclusions: the most important in practice is the power value indicated in W (RMS) at harmonic distortion (THD) values of 1% or less. However, the comparison of products even by this indicator is very approximate and may not have anything to do with reality, because the sound volume is characterized by the sound pressure level. That's why informativeness of the indicator "power of the acoustic system" zero.
Sensitivity
Sensitivity is one of the parameters specified by the manufacturer in the characteristics of acoustic systems. The value characterizes the intensity of the sound pressure developed by the column at a distance of 1 meter when a signal with a frequency of 1000 Hz and a power of 1 W is applied. Sensitivity is measured in decibels (dB) relative to the hearing threshold (zero sound pressure level is 2*10^-5 Pa). Sometimes the designation is used - the level of characteristic sensitivity (SPL, Sound Pressure Level). At the same time, for brevity, dB / W * m or dB / W ^ 1/2 * m is indicated in the column with units of measurement. It is important to understand, however, that sensitivity is not a linear proportionality factor between sound pressure level, signal strength and distance to the source. Many companies list the sensitivity characteristics of dynamic heads, measured under non-standard conditions.
Sensitivity is a characteristic that is more important when designing your own speaker systems. If you do not fully understand what this parameter means, then when choosing multimedia acoustics for a PC, you can not pay much attention to sensitivity (fortunately, it is not often indicated).
frequency response
Frequency response (frequency response) in the general case is a graph showing the difference between the amplitudes of the output and input signals over the entire reproducible frequency range. The frequency response is measured by applying a sinusoidal signal of constant amplitude as its frequency changes. At the point on the graph where the frequency is 1000 Hz, it is customary to plot the level of 0 dB on the vertical axis. The ideal option is in which the frequency response is represented by a straight line, but in reality, acoustic systems do not have such characteristics. When looking at the chart, you need to pay attention Special attention to the amount of unevenness. The greater the amount of unevenness, the greater the frequency distortion of the timbre in the sound.
Western manufacturers prefer to indicate the range of reproducible frequencies, which is a "squeeze" of information from the frequency response: only cutoff frequencies and unevenness are indicated. Suppose it is written: 50 Hz - 16 kHz (± 3 dB). This means that this acoustic system in the range of 50 Hz - 16 kHz has a reliable sound, and below 50 Hz and above 15 kHz, the unevenness increases sharply, the frequency response has a so-called "blockage" (a sharp drop in characteristics).
What does it threaten? Reducing the level of low frequencies implies a loss of juiciness, saturation of the bass sound. The rise in the bass region causes a sensation of mumbling and buzzing of the speaker. in the rubble high frequencies the sound will be dull, unclear. High-frequency rises mean the presence of annoying, unpleasant hissing and whistling overtones. For multimedia speakers, the magnitude of the unevenness of the frequency response is usually higher than that of the so-called Hi-Fi acoustics. All advertising statements of manufacturing companies about the frequency response of a speaker of the type 20 - 20,000 Hz (theoretical limit of possibility) should be treated with a fair amount of skepticism. In this case, the uneven frequency response is often not indicated, which can be unimaginable values.
Since manufacturers of multimedia acoustics often "forget" to indicate the uneven frequency response of the speaker system, when meeting with a speaker characteristic of 20 Hz - 20,000 Hz, you need to keep your eyes open. There is a good chance of buying something that does not even provide more or less uniform response in the 100 Hz - 10,000 Hz frequency band. It is impossible to compare the range of reproducible frequencies with different irregularities at all.
Harmonic distortion, harmonic distortion
Kg coefficient of harmonic distortion. The acoustic system is a complex electro-acoustic device that has a non-linear gain characteristic. Therefore, the signal after all sound path the output will necessarily have non-linear distortion. One of the most obvious and easiest to measure is harmonic distortion.
The coefficient is a dimensionless quantity. Specified either as a percentage or in decibels. Conversion formula: [dB] = 20 log ([%]/100). The higher the harmonic distortion value, the worse the sound is usually.
Kg speakers largely depends on the power of the signal fed to them. Therefore, it is foolish to draw conclusions in absentia or compare speakers only by the harmonic coefficient, without resorting to listening to the equipment. In addition, for the operating positions of the volume control (usually 30..50%), the value is not indicated by manufacturers.
Total electrical resistance, impedance
The electrodynamic head has a certain resistance direct current, depending on the thickness, length and material of the wire in the coil (such resistance is also called resistive or reactive). When a musical signal, which is an alternating current, is applied, the head impedance will change depending on the frequency of the signal.
Impedance(impedans) is the total electrical resistance alternating current measured at a frequency of 1000 Hz. Typically, speaker impedance is 4, 6, or 8 ohms.
In general, the value of the total electrical resistance (impedance) of the speaker system will not tell the buyer about anything related to the sound quality of a particular product. The manufacturer indicates this parameter only so that the resistance is taken into account when connecting the speaker system to the amplifier. If the speaker impedance is lower than the amplifier's recommended load value, the sound may be distorted or short-circuit protected; if higher, the sound will be much quieter than with the recommended resistance.
Speaker box, acoustic design
One of the important factors affecting the sound of a speaker system is the acoustic design of the radiating dynamic head (speaker). When designing acoustic systems, the manufacturer usually faces the problem of choosing an acoustic design. There are more than a dozen types of them.
Acoustic design is divided into acoustically unloaded and acoustically loaded. The first implies a design in which the oscillation of the diffuser is limited only by the rigidity of the suspension. In the second case, the oscillation of the diffuser is limited, in addition to the rigidity of the suspension, by the elasticity of the air and acoustic resistance to radiation. Acoustic design is also divided into single and double action systems. The single action system is characterized by the excitation of the sound going to the listener by means of only one side of the cone (the radiation of the other side is neutralized by the acoustic design). The dual action system involves the use of both surfaces of the cone in the formation of sound.
Since the acoustic design of the speaker practically does not affect the high-frequency and mid-frequency dynamic heads, we will talk about the most common options for low-frequency acoustic design of the cabinet.
The acoustic scheme, called the "closed box", is very widely applicable. Refers to the loaded acoustic design. It is a closed case with a speaker cone displayed on the front panel. Advantages: good frequency response and impulse response. Disadvantages: low efficiency, the need for a powerful amplifier, high level harmonic distortion.
But instead of fighting the sound waves caused by vibrations reverse side diffuser, they can be used. The most common variant of the double-acting systems is the phase inverter. It is a pipe of a certain length and section, built into the body. The length and cross section of the phase inverter are calculated in such a way that at a certain frequency, an oscillation of sound waves is created in it, in phase with the oscillations caused by the front side of the diffuser.
For subwoofers, an acoustic circuit with the generally accepted name "resonator box" is widely used. Unlike the previous example, the speaker cone is not displayed on the case panel, but is located inside, on the partition. The speaker itself does not directly participate in the formation of the low-frequency spectrum. Instead, the diffuser only excites low-frequency sound vibrations, which then multiply in volume in the phase inverter pipe, which acts as a resonant chamber. The advantage of these constructive solutions is high efficiency with small dimensions of the subwoofer. Disadvantages are manifested in the deterioration of the phase and impulse response, the sound becomes fatiguing.
The best choice would be medium-sized speakers with wooden case made according to a closed circuit or with a phase inverter. When choosing a subwoofer, you should pay attention not to its volume (by this parameter, even inexpensive models usually have a sufficient margin), but to reliable reproduction of the entire low frequency range. In terms of sound quality, speakers with a thin body or very small sizes are most undesirable.
]Usually, decibels are used to measure the loudness of a sound. A decibel is a decimal logarithm. This means that increasing the volume by 10 decibels indicates that the sound has become twice as loud as it was originally. The loudness of a sound in decibels is usually described by the formula 10Log 10 (I/10 -12), where I is the sound intensity in watts/square meter.
Steps
Comparative table of noise levels in decibels
The table below describes the decibel levels in ascending order, and their corresponding sound source examples. Information is also provided on the adverse effects on hearing against each noise level.
| decibels | Source Example | Health impact |
|---|---|---|
| 0 | Silence | Missing |
| 10 | Breath | Missing |
| 20 | Whisper | Missing |
| 30 | Quiet background noise in nature | Missing |
| 40 | Sounds in the library, quiet background noise in the city | Missing |
| 50 | Quiet conversation, typical suburban background noise | Missing |
| 60 | Office or restaurant noise, loud conversation | Missing |
| 70 | TV, highway noise from 15.2 meters (50 feet) away | The note; unpleasant to some |
| 80 | Noise from factory, food processor, car wash from 6.1 meters (20 feet) away | Possible hearing damage from prolonged exposure |
| 90 | Lawn mower, motorcycle from a distance of 7.62 m (25 ft) | High chance of hearing damage with prolonged exposure |
| 100 | Boat motor, jackhammer | High risk of severe hearing damage with prolonged exposure |
| 110 | Loud rock concert, steel mill | It may hurt right away; very high risk of severe hearing damage with prolonged exposure |
| 120 | Chainsaw, thunder | Usually there is immediate pain |
| 130-150 | Fighter takeoff from an aircraft carrier | Possible immediate hearing loss, or rupture of the eardrum. |
Sound level measurement with instruments
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Use the mobile app. To measure sound level anywhere, mobile applications will come in handy. microphone on your mobile device it probably won't deliver the same quality as an external microphone connected to your computer, but it can be surprisingly accurate. For example, the reading accuracy of mobile phone may well differ by 5 decibels from professional equipment. Below is a list of programs for reading the sound level in decibels for different mobile platforms:
- For Apple devices: Decibel 10th, Decibel Meter Pro, dB Meter, Sound Level Meter
- For Android devices: Sound Meter, Decibel Meter, Noise Meter, deciBel
- For Windows phones: Decibel Meter Free, Cyberx Decibel Meter, Decibel Meter Pro
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Use a professional decibel meter. It's usually not cheap, but it's probably the easiest way to get accurate measurements of the sound level you're interested in. Also referred to as a "sound level meter", this is a specialized device (available online or in specialized stores) that uses a sensitive microphone to measure the noise level around and gives an accurate decibel reading. Because similar devices are not in high demand, they can be quite expensive, often starting at $200 even for entry-level devices.
- Note that the decibel/sound level meter may call it something different. For example, another similar device called a "noise meter" does the same thing as a sound level meter.
Mathematical calculation of decibels
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Find out the sound intensity in watts/square meter. In everyday life, decibels are used as a simple measure of loudness. However, everything is not so simple. In physics, decibels are often viewed as a convenient way of expressing the "intensity" of a sound wave. The greater the amplitude of the sound wave, the more energy it transmits, the more air particles vibrate in its path, and the more intense the sound itself. Due to the direct relationship between the intensity of a sound wave and the loudness in decibels, it is possible to find the decibel value by knowing only the intensity of the sound level (which is usually measured in watts/meter squared)
- Note that for normal sounds the intensity value is very low. For example, a sound with an intensity of 5 × 10 -5 (or 0.00005) watts/meter square corresponds to approximately 80 decibels, which is approximately the volume of a blender or food processor.
- To better understand the relationship between intensity and decibel level, let's solve one problem. Let's take this as an example: let's say that we are sound engineers and we need to get ahead of the background noise level in a recording studio in order to improve the quality of the recorded sound. After installing the equipment, we fixed the background noise with an intensity 1 × 10 -11 (0.00000000001) watt/square meter. Using this information, we can then calculate the background noise level of the studio in decibels.
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Divide by 10 -12. If you know the intensity of your sound, you can easily plug it into the formula 10Log 10 (I/10 -12) (where "I" is the intensity in watts/meter squared) to get the value in decibels. To start, divide 10 -12 (0.000000000001). 10 -12 displays the sound intensity with a rating of 0 on the decibel scale, comparing your sound intensity with this number you will find its relation to the initial value.
- In our example, we divided the intensity value 10 -11 by 10 -12 and got 10 -11 / 10 -12 = 10 .
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Calculate Log 10 from this number and multiply it by 10. To complete the solution, all you have to do is take the base 10 logarithm of the resulting number and then finally multiply it by 10. This confirms that decibels are logarithmic to base 10—in other words, a 10 decibel increase in noise level means doubling sound volume.
- Our example is easy to solve. Log 10 (10) = 1. 1 × 10 = 10. Therefore, the background noise value in our studio is 10 decibels. It's quiet enough, but still picked up by our high quality recording equipment, so we probably need to eliminate the source of the noise in order to achieve more High Quality records.
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Understanding the logarithmic nature of decibels. As stated above, decibels are logarithmic values to base 10. For any given decibel value, noise 10 decibels large is twice as loud, noise 20 decibels as large is four times louder, and so on. This makes it possible to designate a wide range of sound intensities that can be perceived by the human ear. The loudest sound a person can hear without pain is a billion times louder than the quietest sound a person can hear. By using decibels, we avoid using huge numbers to describe ordinary sounds - instead, three digits are enough for us.
- Think about which is easier to use: 55 decibels or 3 × 10 -7 watts / square meter? Both values are equal, but instead of using the scientific notation (as a very small fraction of a number), it's much more convenient to use decibels, which are sort of a simple shorthand for easy everyday use.
Use your computer. So special programs and equipment, it is easy to measure the noise level in decibels directly on the computer. Listed below are just some of the ways this can be done. Note that using better recording equipment will always give better results; in other words, your laptop's built-in microphone may be sufficient for some tasks, but a high-quality external microphone will produce more accurate results.
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