CN100574515C - The loudspeaker unit resonance frequency temperature drift characteristic during high power work assay method - Google Patents

Abstract

The measurement method of the resonant frequency temperature drift characteristic of the loudspeaker unit during high-power operation, through the temperature drift formula of the resonant frequency when the loudspeaker unit works under high-power conditions, and by using the lumped parameter analog circuit to describe the heat dissipation path inside the loudspeaker unit, gives The relationship formula between the surface temperature of the centering strut and the temperature of the voice coil in the unit is obtained, and the formula of the change of the resonance frequency with the temperature of the voice coil is deduced; The temperature drift characteristics of the surface temperature change, calculate the temperature drift characteristics of the resonant frequency with the change of the voice coil temperature, and then predict the resonant frequency at different voice coil temperatures and the surface temperature of the centering piece. Model formulations, determinations and predictions involving the resonant frequency temperature drift characteristics of loudspeaker units. The invention measures the temperature drift characteristic of the resonant frequency of the loudspeaker unit, and predicts the resonant frequency drift when the temperature of the voice coil and the surface temperature of the centering piece change accordingly.

Description

Measurement method of resonant frequency temperature drift characteristic of loudspeaker unit at high power operation

1. Technical field

The invention relates to the detection of the resonant frequency of the loudspeaker unit, which is used to evaluate and improve the performance of the loudspeaker unit during high-power operation; especially the model formula, measurement and prediction of the temperature drift characteristic of the resonant frequency of the loudspeaker unit.

2. Background technology

<1> The significance of measuring the temperature drift characteristics of the resonant frequency of the loudspeaker unit under high-power working conditions

The resonance frequency is the basic parameter of the speaker unit, which plays a decisive role in the performance and effect of the speaker unit. The resonant frequency is determined by the equivalent compliance and equivalent vibration mass of the vibration system of the speaker unit. The equivalent vibration mass is approximately constant, and the equivalent compliance will change with the displacement of the voice coil and the external conditions. So far, the research on the force flow of the vibration system is mostly limited to the linearity of the force flow with the change of the voice coil displacement. When considering the influence of external conditions, Lishun is jointly determined by the damper and the ring. It is generally believed that the elastic coefficients of the two are affected by the temperature and humidity of the atmosphere, and can be measured under different environmental conditions. In the case of replaying small signals and the difference between the internal temperature of the speaker unit and the ambient temperature is very small, the force smoothness of the vibration system can be considered to be equal to the value measured at the ambient temperature. However, in many practical applications, the speaker unit works for a long time under a relatively large signal. At this time, the internal temperature of the speaker unit increases, the elastic coefficient of the centering piece decreases, and the compliance increases. The farther the circle is, the compliance change is small, but the force compliance of the vibration system has changed significantly, resulting in a large shift in the resonant frequency of the unit. Therefore, it is necessary to measure the temperature drift characteristics of the resonant frequency of the loudspeaker unit under high-power working conditions, which can be used to evaluate and improve the performance of the loudspeaker unit under high-power working conditions.

None of the existing conventional electroacoustic measurement methods and instruments have considered nor have the function of measuring the temperature drift characteristics of the resonant frequency of the loudspeaker unit under high-power working conditions.

<2> Existing technology or method

The research on the centering support piece Lishun of the loudspeaker unit has been carried out mainly as follows:

A) Steven Hutt. "Loudspeaker Spider Linearity" (The linearity of the speaker centering piece, the 108th [International] Audio Engineering Society Conference, The 108th Convention of the Audio Engineering Society, Paris, 2000. Preprint 5159) compared several different For the geometric structure and different materials of the damper, it is proposed to use gradual undulations to improve the linearity of the damper.

B) Hiroshi Watanebe. "Improvement of Suspension Linearity in Loudspeakers by Means of Biased Suspension" (Using a biased structure to improve the linearity of the speaker suspension system, the 79th [International] Audio Engineering Society Conference, The 79th Convention of the Audio Engineering Society, New York, 1985. Preprint 2283) proposed the use of double centering strut oblique structure in the speaker unit, which can increase the linearity of the centering strut and reduce the second and third harmonic distortion.

These works are limited to the study of how to improve the linearity of the damper's force-shun variation with the voice coil displacement, and have not considered the force-shun variation of the damper due to the increase of the surrounding air temperature under high-power working conditions.

C) Steven Hutt. "Ambient Temperature Influences on OEM Automotive Loudspeakers" (the impact of ambient temperature on OEM automotive speakers, the 112th [International] Audio Engineering Society Conference, The112th Convention of the Audio Engineering Society Munich, 2002. Preprint 5507) using Klippel distortion analyzer and constant temperature box measured the influence of ambient temperature on car speaker unit parameters, and compared the unit parameters measured under different ambient temperatures, mainly the resonant frequency of the unit and the elastic coefficient of the vibration system (that is, the reciprocal of Lishun) .

This paper considers the influence of the temperature of the environment where the loudspeaker is located on the performance of the loudspeaker unit, and does not take into account the changes in the performance of the unit caused by the increase in the temperature of the air near the strut under high-power working conditions.

D) Wolfgang Klippel. "Dynamical Measurement of Loudspeaker Suspension Parts (dynamic measurement method of loudspeaker unit parts, the 117th [International] Audio Engineering Society Conference The 117thConvention of the Audio Engineering Society, San Francisco, 2004. Preprint 6179) proposed a A special device is used to measure the force smoothness of the speaker unit paper cone, centering strut and ring; it is pointed out that the usually measured force smoothness is only an effective average value, which is approximately constant when the signal is small, and the force smoothness of the centering strut when the signal is large The shunt value changes non-linearly with the change of voice coil displacement, and the resonant frequency at this time also changes accordingly.

The paper has noticed that the elastic coefficient curve of the vibration system will produce "irregular variations" (Irregular Variations) as the voltage increases or the working time of the unit becomes longer, but only a speculative explanation is given, which is considered to be due to the expansion and contraction of the material and aging and other reasons. The contents of the present invention can make qualitative and quantitative explanations for the above phenomena, and thus deduce the change of unit resonance frequency.

3. Contents of the invention

The purpose of the present invention is to use conventional temperature measuring equipment and electroacoustic measuring instruments to measure the temperature drift characteristics of the resonant frequency under high-power working conditions according to the temperature drift formula of the resonant frequency of the loudspeaker unit under high-power working conditions, and predict the voice coil accordingly Resonant frequency shift with temperature and spider surface temperature changes.

The method of the present invention is based on the following mechanism: the elastic coefficient of the vibration system of the known loudspeaker unit is jointly contributed by the strut and the ring, and the surface temperature of the strut will increase with the increase of the nearby air temperature under high power conditions, resulting in a constant The core piece becomes softer, the compliance increases, and the elastic coefficient decreases. Therefore, the temperature drift formula of the elastic coefficient of the vibration system is:

k _ms =k _sp +k _su =k _sp0 +a _sp ΔT _s +k _su =(k _sp0 +k _su )+a _sp ΔT _s =k _ms0 +a _sp ΔT _s

Accordingly, the formula for the change of unit resonant frequency with the surface temperature of the damper is:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}}<span\; class="notranslate">\; =</span>\frac{\sqrt{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="k\; ms"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">k</figure-callout></span><figure-callout\; id="2"\; label="k\; ms"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}}<span\; class="notranslate">\; =</span>\frac{\sqrt{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="k\; ms"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">k</figure-callout></span><figure-callout\; id="0"\; label="k\; ms"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; sp</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="0"\; label="s"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 0</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; sp</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}$

The object of the present invention is achieved like this: measure the method for the temperature excursion characteristic of resonant frequency under the loudspeaker unit high-power working condition, according to the temperature excursion formula of loudspeaker unit resonant frequency, detect centering strut surface temperature and Use electroacoustic frequency and power measuring instruments to measure the temperature drift characteristics of the resonant frequency changing with the surface of the centering piece and the temperature of the voice coil, and obtain the temperature drift characteristics of the resonant frequency changing with the temperature of the voice coil, and then predict different voice coil temperatures and centering struts. Resonant frequency at sheet surface temperature.

The temperature drift formula of the resonant frequency of the loudspeaker unit based on the change of the surface temperature of the above-mentioned centering strut:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="0"\; label="s"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 0</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; sp</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}$

The temperature drift coefficient of the resonant frequency with the change of the surface temperature of the damper and the temperature of the voice coil is measured and fitted with conventional temperature measuring equipment and electroacoustic measuring instruments.

And use the measured and calculated temperature drift coefficient and the resonant frequency measured when replaying small signals at ambient temperature to calculate and predict the resonant frequency of the loudspeaker unit under different centering plate surface temperature and voice coil temperature.

A set of ΔT _s ~ f _s data is measured by an infrared thermometer and a conventional electroacoustic measuring instrument, and the temperature drift coefficient β _sp of the unit resonant frequency changing with the surface temperature of the centering support can be obtained by fitting calculation.

The lumped parameter analog circuit for establishing the internal heat dissipation path of the loudspeaker unit is shown in Figure 1. The strut and the surrounding air are regarded as isothermal, so the ratio of the surface temperature of the strut to the voice coil temperature is only Related to voice coil amplitude and velocity:

$\frac{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; ts</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; tc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; ts</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; ts</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; ts</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R\; ts"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">R</figure-callout></span><figure-callout\; id="2"\; label="R\; ts"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; tc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R\; tc"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">R</figure-callout></span><figure-callout\; id="2"\; label="R\; tc"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span>$

For the replay signal with fixed size and fixed spectral components, λ _sc (x, v) is a constant, use a DC additional circuit and an infrared thermometer to measure a set of ΔT _c ~ ΔT _s data, and fit the calculation to get λ _sc (x,v).

And then can deduce the formula that unit resonant frequency changes with voice coil temperature, namely the temperature drift formula that the loudspeaker unit resonant frequency of the present invention changes with voice coil temperature:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="0"\; label="s"\; filenames="C2005100945120008H2.png,C2005100945120009H1.png"\; state="\{\{state\}\}">s</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 0</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; sp</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; sc</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}$

Therefore, according to the above temperature drift formula of the resonant frequency f _s of the two loudspeaker units and the known f _s0 , β _sp , λ _sc (x, v), the temperature of the voice coil and the surface temperature of the centering piece can be predicted the resonant frequency.

The characteristics of the present invention are: according to the temperature drift formula of the resonant frequency of the loudspeaker unit, the temperature drift characteristics of the resonant frequency changing with the surface temperature of the centering piece are measured with conventional temperature measuring equipment and electroacoustic measuring instruments, and the resonant frequency is calculated as the temperature of the voice coil changes. The temperature drift characteristics of temperature changes can predict the change of resonance frequency under different working temperatures (voice coil temperature and centering support piece surface temperature) inside the unit, which is convenient and quick to use. It can calculate and predict the resonant frequency under different voice coil temperature and spider surface temperature. It is very meaningful for the design, manufacture and quality control of loudspeakers and the control of high-power working conditions and conditions.

The invention proposes the temperature drift phenomenon of the resonant frequency and its model formula when the loudspeaker unit works under the condition of high power, and provides the measurement and prediction of the resonant frequency with the temperature and centering of the voice coil by using conventional temperature measuring equipment and electroacoustic measuring instruments. The method of the change law of the surface temperature of the support piece.

4. Description of drawings

Fig. 1 The present invention is the lumped parameter analog circuit of the internal heat dissipation path of the loudspeaker unit established by estimating the relationship between the surface temperature of the centering strut and the voice coil temperature. In the figure, P _re is the thermal power of the voice coil, P _ed is the thermal power corresponding to the eddy current thermal effect, R _iv and R _im are the total thermal resistances from the voice coil to the magnet and from the magnet to the surrounding air respectively, C _tv , C _tm , C _ts is the total heat capacity of the voice coil, magnet and spider respectively, ΔT _c , ΔT _m , and ΔT _s are the changing temperatures of the voice coil, magnet and spider respectively, T _a is the ambient temperature, R _tc1 (v ), R _tc2 are the forced convection heat dissipation from the voice coil to the spider and the thermal resistance corresponding to conduction and radiation heat dissipation, R _ts1 (x), R _ts2 are the forced convection heat dissipation from the spider to the surrounding air and Thermal resistance corresponding to conduction and radiation heat dissipation;

Fig. 2 is the change curve ΔT _s ~ f _s of the resonant frequency of the loudspeaker unit fitted with the method of the present invention with the surface temperature of the centering strut and the measured data: (a) full-band loudspeaker unit a; (b) woofer unit b;

Fig. 3 is the relationship curve ΔT _c ~ ΔT _s between the surface temperature of the centering piece of the speaker unit and the temperature of the voice coil fitted by the method of the present invention and the measured data: (a) full-band speaker unit a; (b) woofer unit b;

Figure 4 DC additional circuit diagram, used to measure the ΔT _c ~ ΔT _s data of units a and b together with the infrared thermometer

5. Specific implementation

Specific embodiments of the present invention:

The temperature drift characteristics of the resonant frequency when two loudspeaker units of different sizes are actually measured under the high power condition are measured with the present invention. Unit a is a rectangular full-band loudspeaker (14cm×4cm), and unit b is a woofer with a diameter of 16cm.

Firstly, the resonant frequency f _s0 of units a and b when playing back small signals at ambient temperature is measured by conventional electro-acoustic measuring instruments, see Table 1.

Then use the infrared thermometer and the conventional electroacoustic measuring instrument to measure the ΔT _s ~ f _s data of the units a and b, and fit the calculation to obtain the temperature of the resonant frequency of the units a and b changing with the surface temperature of the centering support Drift coefficient β _sp , see Table 1. The measured ΔT _s ~ f _s data and fitting curve are shown in Fig. 2 .

Then use the DC additional circuit and the infrared thermometer to measure the ΔT _c ~ ΔT _s data of the units a and b, and the fitting calculation can obtain the surface temperature of the centering piece and the voice coil of the unit a and b under the playback signal. See Table 1 for the temperature proportionality coefficient λ _sc (x, v). The measured ΔT _c ~ ΔT _s data and fitting curve are shown in Fig. 3 .

As shown in Figure 4: For a replay signal with a fixed size and a fixed spectral component, λ _sc (x, v) is a constant, use a DC additional circuit and an infrared thermometer to measure a set of ΔT _c ~ ΔT _s data, and the fitting calculation is λ _sc (x, v) can be obtained.

Table 1 Relevant parameters of the resonant frequency temperature drift characteristics of the speaker unit under high power conditions

unit f_s0(Hz) β_sp λ_sc(x, v) a 189.2 -0.0022 0.330 b 58.0 -0.0061 0.111

Therefore, the drift characteristics of the resonant frequency of the loudspeaker unit with the change of the surface temperature of the centering piece under the high-power working condition can be predicted:

unit a: $f_{\mathrm{the\; s}}=189.2\sqrt{1-0.0022\mathrm{\&Delta;}{T}_{\mathrm{the\; s}}}$

Unit b: $f_{\mathrm{the\; s}}=58\sqrt{1-0.0061\mathrm{\&Delta;}{T}_{\mathrm{the\; s}}}$

And the drift characteristics of the resonant frequency changing with the voice coil temperature under the high-power working condition of the speaker unit:

unit a: $f_{\mathrm{the\; s}}=189.2\sqrt{1-7.26\&times;{10}^{-3}\mathrm{\&Delta;}{T}_c}$

Unit b: $f_{\mathrm{the\; s}}=58\sqrt{1-6.77\&times;{10}^{-3}\mathrm{\&Delta;}{T}_c}$

Claims (1)

1, the temperature drift characteristic assay method of loudspeaker unit resonance frequency during a kind of high power work is characterized in that step is as follows:

Resonance frequency f when 1) utilizing conventional electroacoustic measurement instrument to record loudspeaker unit to reset small-signal at ambient temperature _S0

2) detect the centring disk surface temperature with infrared radiation thermometer, obtain centring disk surface temperature change Δ T _sWith the resonance frequency f of usefulness electroacoustic measurement Instrument measuring loudspeaker unit under this temperature _s, obtain one group of Δ T _s～f _sData, The Fitting Calculation go out the temperature drift coefficient β of the resonance frequency of loudspeaker unit with the variation of centring disk surface temperature _Sp

3) utilize direct current adjunct circuit and infrared radiation thermometer to measure the variations in temperature Δ T of loudspeaker unit voice coil loudspeaker voice coil _cWith loud speaker centring disk surface temperature change Δ T _s, obtain one group of Δ T _c～Δ T _sData, The Fitting Calculation go out the centring disk surface temperature of loudspeaker unit under this replay signal and change the proportionality coefficient λ that changes with voice coil temperature _Sc(x, v), wherein ${\mathrm{\&lambda;}}_{\mathrm{sc}}(x,v)=\frac{\mathrm{\&Delta;}{T}_s}{\mathrm{\&Delta;}{T}_c};$

4) with f _S0, β _SpThe temperature drift formula that the substitution loudspeaker unit resonance frequency changes with the centring disk surface temperature $f_s=f_{s0}\sqrt{1+{\mathrm{\&beta;}}_{\mathrm{sp}}\mathrm{\&Delta;}{T}_s}---\left(1\right),$

The drift characteristic that resonance frequency changes with the centring disk surface temperature under the measurable loudspeaker unit high power work condition;

With f _S0, β _Sp, λ _Sc(x, v) the substitution loudspeaker unit resonance frequency is with the temperature drift formula of voice coil temperature variation

$f_s=f_{s0}\sqrt{1+{\mathrm{\&beta;}}_{\mathrm{sp}}{\mathrm{\&lambda;}}_{\mathrm{sc}}(x,v)\mathrm{\&Delta;}{T}_c}---\left(2\right)$

The drift characteristic that resonance frequency changes with voice coil temperature under the measurable loudspeaker unit high power work condition;

Resonance frequency temperature drift characteristic during 5) according to above-mentioned loudspeaker unit high power work, and then the resonance frequency of loudspeaker unit under measurable different centring disk surface temperature and the voice coil temperature.

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