Equal-loudness-level curve calculation method suitable for plug-in earphone

Abstract

The invention relates to the technical field of psychoacoustic and electroacoustic measurement, and provides an equal-loudness-level curve calculation method suitable for a plug-in headphone, and the method comprises the steps: firstly, calculating a free field equal-loudness-level curve based on a standard, and deducing an increment function representing a human ear loudness perception growth rate; then, acquiring a pure tone reference equivalent threshold sound pressure level of the plug-in earphone in a blocked ear environment, and realizing full-frequency-point reference data fitting by using an interpolation algorithm; and finally, superposing the loudness increment function on the reference equivalent threshold sound pressure level reference anchor point, thereby constructing an equal loudness level curve suitable for the plug-in earphone. The technical blank that the plug-in earphone lacks an equal-loudness evaluation standard in a blocked ear scene is solved, and an important support and an application basis are provided for application expansion of an equal-loudness-level curve relation.

Description

Technical Field

[0001] This invention relates to the field of psychoacoustics and electroacoustic measurement technology, specifically to a method for calculating the equal loudness level curve of plug-in headphones. Background Technology

[0002] According to the current industry standard GB / T 4963-2007 "Acoustic Standard Equal Loudness-Level Contours" (equivalent to ISO226:2003), equal loudness-level contours (ELLCs) are curves showing the relationship between sound pressure level and frequency for pure tones that are perceived as having the same loudness by typical listeners. The normal equal loudness-level contour refers to the average equal loudness-level contour of a normal otolaryngological population aged 18–25 (referred to as the "standard curve").

[0003] The applicable conditions for the standard equal loudness level curve specified in GB / T 4963-2007 (eqv ISO 226:2003) are: a) the sound field consists of free-plane traveling waves when the listener is not present; b) the sound source is in front of the listener; c) the sound signal is a pure tone; d) the sound pressure level is measured at the center of the listener's head, but the listener is not present; e) binaural audiometry; f) the listener is an ear-normal person aged 18-25 years. The key characteristic is that the sound field is a free field composed of free-plane traveling waves.

[0004] However, in the application scenario of in-ear headphones, due to the blockage of the ear canal by the earplug, its acoustic impedance, resonance characteristics, and sound field distribution differ significantly from those of a free field. Therefore, for the acoustic scenario of in-ear headphones in an occluded ear, there is currently a lack of a usable standard for "loudness level curves of in-ear headphones," that is, a standard similar to GB / T 4963-2007 (eqv ISO 226:2003) corresponding to a free field with a sound field composed of free plane traveling waves. There is a lack of domestic and international standards for calculating loudness level curves specifically for the "in-ear headphone scenario." Therefore, a calculation method is needed to extend the applicable sound field range of existing loudness level curves (ELLCs), extending the "loudness growth law" of the free field standard loudness level curve to the occluded ear scenario of in-ear headphones, thereby establishing a loudness level curve suitable for in-ear headphones. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a comprehensive model calculation method based on free-field nonlinear incremental transfer and reference threshold anchoring. It characterizes the nonlinear increment of human ear loudness perception based on the equal-loudness level curve relationship under free-field conditions, and uses the pure-tone reference equivalent threshold sound pressure level (RETSPL) of a plug-in headphone as the reference anchor point for hearing threshold. This achieves a comprehensive calculation model that considers both the acoustic characteristics of the plug-in headphone in the initial threshold stage and introduces the equal-loudness level compensation amount that varies with sound pressure level, thereby establishing an equal-loudness level curve suitable for plug-in headphones.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for calculating the equal loudness level curve for plug-in headphones includes the following steps:

[0008] S1: Based on a pre-defined free-field equal loudness level model, calculate different frequencies. With different loudness levels Free-field equal loudness level curve and the reference hearing threshold baseline under free-field conditions. ;

[0009] S2: Calculate the free-field equal-loudness level curves at various loudness levels. Reference hearing threshold baseline under free-field conditions The difference between them is used to construct the loudness perception increment function.

[0010] S3: Obtain the pure-tone reference equivalent threshold sound pressure level function of the target in-ear headphone under occluded conditions. ,

[0011] S4: Convert the pure tone reference equivalent threshold sound pressure level function As the hearing threshold anchor point, the human ear loudness perception increment function is superimposed. A comprehensive calculation model for equal loudness level curves suitable for the plug-in headphones is constructed. .

[0012] Preferably, the equal loudness level curve under the free field condition described in step S1 From loudness level Solve for the corresponding equal loudness level curves The expression is:

[0013] ,

[0014] in, ,

[0015] For frequency The value; The loudness perception power index; This is the free-field hearing threshold at that frequency. It is the amplitude of the linear transfer function normalized to 1000Hz.

[0016] Preferably, the loudness perception increment function in step S2 The expression is:

[0017] .

[0018] Preferably, in step S3, the step of obtaining the pure-tone reference equivalent threshold sound pressure level function RETSPL(f) of the target in-ear headphone includes:

[0019] Obtain the headphones at multiple standard discrete frequency points Pure tone reference equivalent threshold sound pressure level data ;

[0020] For the discrete data Interpolation is performed to obtain the pure tone reference equivalent threshold sound pressure level function at continuous frequencies. .

[0021] Preferably, the interpolation process employs linear interpolation, polynomial interpolation, or spline interpolation methods.

[0022] Preferably, the target plug-in earphone is a plug-in earphone that conforms to a preset occlusion acoustic calibration standard.

[0023] Preferably, in step S4, a comprehensive calculation model for equal loudness level curves suitable for plug-in headphones is constructed, and the expression is:

[0024] ,

[0025] ,

[0026] in, The decision was made to block the hearing threshold anchor point. This determines the nonlinear incremental trend as the loudness level increases.

[0027] Preferably, the comprehensive calculation model of the equal loudness level curve generated in step S4 It is configured to output in at least one of the following forms:

[0028] a) by frequency and loudness level A two-dimensional data table indexed by;

[0029] b) Using a specific set of loudness levels A set of equal loudness level curves with parameters;

[0030] c) Calculation function interfaces integrated into the software system.

[0031] This invention provides a method for calculating the equal loudness level curve for in-ear headphones. It offers the following advantages: by extracting the dynamic increment function of the free-field equal loudness curve and combining it with the pure-tone reference equivalent threshold sound pressure level (RETSPL) specific to in-ear headphones, it achieves cross-scenario migration from a free-field model to an ear-blocking model; it fills the gap in understanding the correspondence between sound pressure levels at different frequencies and loudness levels in the ear-blocking scenario of in-ear headphones.

[0032] The dedicated equal-loudness level curves generated by this method can be used to guide the frequency response tuning of plug-in headphones, the loudness balance optimization of active noise cancellation algorithms, and the development of high-precision volume and loudness management functions in personal audio devices. On the testing side, it provides a more accurate objective acoustic reference for standardized subjective listening evaluation. Attached Figure Description

[0033] Figure 1 This is a flowchart of the comprehensive calculation model for equal loudness level curves of plug-in headphones proposed in this invention.

[0034] Figure 2 This is a schematic diagram of the equal loudness level curve results for plug-in headphones established using the method of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] See attached document Figure 1 As shown, a method for calculating the equal loudness level curve for plug-in headphones includes the following steps:

[0037] S1: Based on the parameter table of GB / T 4963-2007 "Acoustic Standard Equal Loudness Level Curves" (equivalent to ISO 226:2003),

[0038] Based on a pre-defined free-field equal loudness level model, calculations are performed at different frequencies. With different loudness levels Free-field equal loudness level curve and the reference hearing threshold (0phon) baseline under free-field conditions. ;

[0039] S2: Calculate the free-field equal-loudness level curves at various loudness levels. Baseline hearing threshold (0phon) under free-field conditions The difference between them is used to construct the loudness perception increment function.

[0040] S3: According to GB / T 16402-1996 "Acoustic plug-in headphones pure tone reference equivalent threshold sound pressure level" (equivalent to ISO 389-2:1994);

[0041] Obtain the pure-tone reference equivalent threshold sound pressure level function of the target in-ear headphone (coupled cavity or ear simulator) under occluded conditions. ,

[0042] S4: Convert the pure tone reference equivalent threshold sound pressure level function As a hearing threshold anchor point (enabling the established equal loudness level curve to be directly consistent with the calibration standard of plug-in headphones, which can be used for engineering implementation and measurement traceability), the human ear loudness perception increment function is superimposed. A comprehensive calculation model for equal loudness level curves suitable for the plug-in headphones is constructed. .

[0043] The equal loudness level curve under the free field condition described in step S1 Loudness levels can be referenced in GB / T 4963-2007 (eqv ISO 226:2003). The conversion between phon and sound pressure level (dB SPL) is based on loudness level. Solve for the corresponding equal loudness level curves The expression is:

[0044] ,

[0045] in, ,

[0046] For frequency The value; The loudness perception power index; This is the free-field hearing threshold at that frequency. It is the amplitude of the linear transfer function normalized to 1000Hz;

[0047] The lower limit of loudness level is 20 phons, while the upper limit (phons) depends on the frequency range; the specific applicable ranges are as follows:

[0048] frequency Loudness level 20~4kHz 20-90phon 5k~12.5kHz 20-80phon

[0049] In step S1, with frequency Related preset parameters , and The values ​​are obtained by querying a preset parameter table, which contains at least multiple discrete frequency points corresponding to frequencies ranging from 20Hz to 12500Hz. , and Numerical value;

[0050] Loudness level under free field conditions in step S1 Reference hearing threshold baseline when phon is 0 .

[0051] loudness perception increment function in step S2 Free-field equal loudness level curve Reference hearing threshold baseline under free-field conditions The difference between them, its increment function The expression is:

[0052] ,

[0053] The loudness perception increment function It is used to characterize the growth rate of human ear's perception of loudness, and is frequency. and loudness level The loudness increment function is a function of phon; this part assumes that the loudness increase rate of the human ear in a free field and when wearing headphones is similar; the loudness perception increment function is constructed by the difference between the free field equal loudness level curve and the baseline. It retains the "nonlinear loudness growth with frequency and intensity" characteristic described in GB / T 4963-2007 (eqv ISO 226:2003), and avoids the distortion of equal loudness curve spacing caused by simple translation.

[0054] In step S3, the pure-tone reference equivalent threshold sound pressure level function of the target in-ear headphone is obtained. The steps include:

[0055] Obtain the headphones at multiple standard discrete frequency points Pure tone reference equivalent threshold sound pressure level data ;

[0056] For the discrete data Interpolation is performed to obtain the pure tone reference equivalent threshold sound pressure level function at continuous frequencies. The unit is dB SPL.

[0057] The interpolation process employs linear interpolation, polynomial interpolation, or spline interpolation methods.

[0058] The target plug-in earphone is a plug-in earphone that conforms to a preset occlusion acoustic calibration standard.

[0059] The comprehensive calculation model in step S4 uses the pure tone reference equivalent threshold sound pressure level function of the plug-in earphone obtained in step S3. As a baseline, the loudness perception increment function obtained in step S2 is superimposed. A comprehensive calculation model for equal loudness level curves suitable for plug-in headphones is constructed, and the expression is:

[0060] ,

[0061] ,

[0062] in, This determines the initial state of blocking the hearing threshold anchor point. This determines the nonlinear incremental trend as the loudness level increases.

[0063] This allows for the simultaneous fulfillment of both "hearing threshold reference consistent with calibration standards" and "preservation of the nonlinear equal loudness law of ISO226" in the context of plug-in headphones.

[0064] The comprehensive calculation model of the equal loudness level curve generated in step S4 It is configured to output in at least one of the following forms:

[0065] a) by frequency and loudness level A two-dimensional data table indexed by phon;

[0066] b) Using a specific set of loudness levels A set of equal loudness level curves with parameters;

[0067] c) Calculation function interfaces integrated into the software system.

[0068] The plug-in earphone model must meet the conditions specified in GB / T 16402-1996 (eqv ISO 389-2:1994), namely, the Etymotic Research ER-3A plug-in earphone coupled to the human ear with the ER-3-14 type earplug; earphones that meet the conditions will produce different reference equivalent threshold sound pressure levels (i.e., different RETSPL) when plugged into different types of coupling cavities and ear simulators.

[0069] The tables in GB / T 16402-1996 (eqv ISO 389-2:1994) provide data for two sets of reference equivalent threshold sound pressure levels (RETSPL) for plug-in headphones in an acoustic coupling cavity conforming to SJ / Z9144—87, or in an occluded ear simulator conforming to SJ / Z9150—87.

[0070] The interpolation method described above is used to reasonably calculate the RETSPL at other frequency points. This interpolation method can use various interpolation methods in curve fitting to fit existing data, obtaining the equivalent threshold sound pressure level (RTSPL) of the pure tone reference for the plug-in headphones, denoted as... .

[0071] Figure 2 As shown, the equal loudness level curve mainly involves three units: frequency (in Hz), sound pressure level (in dB SPL), and loudness level (in phon). The horizontal axis represents frequency, and the vertical axis represents sound pressure level. Points on the same curve of the equal loudness level curve correspond to the same frequency and sound pressure combination, which have the same loudness level. This curve represents the relationship between sound pressure level and frequency while keeping the loudness level constant. In other words, it shows that different sound pressure levels are required at different frequencies for the listener to perceive a consistent loudness.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the equal loudness level curve of plug-in headphones, characterized in that, Includes the following steps: S1: Based on a pre-defined free-field equal loudness level model, calculate different frequencies. With different loudness levels Free-field equal loudness level curve and the reference hearing threshold baseline under free-field conditions. ; S2: Calculate the free-field equal-loudness level curves at various loudness levels. Reference hearing threshold baseline under free-field conditions The difference between them is used to construct the loudness perception increment function. ; S3: Obtain the pure-tone reference equivalent threshold sound pressure level function of the target in-ear headphone under occluded conditions. , S4: Convert the pure tone reference equivalent threshold sound pressure level function As the hearing threshold anchor point, the human ear loudness perception increment function is superimposed. A comprehensive calculation model for equal loudness level curves suitable for the plug-in headphones is constructed. .

2. The method for calculating the equal loudness level curve of a plug-in earphone according to claim 1, characterized in that, The equal loudness level curve under the free field condition described in step S1 From loudness level Solve for the corresponding equal loudness level curves The expression is: ， in, , For frequency The value; The loudness perception power index; This is the free-field hearing threshold at that frequency. It is the amplitude of the linear transfer function normalized to 1000Hz.

3. The method for calculating the equal loudness level curve of a plug-in earphone according to claim 1, characterized in that, loudness perception increment function in step S2 The expression is: 。 4. The method for calculating the equal loudness level curve of a plug-in earphone according to claim 1, characterized in that, In step S3, the pure-tone reference equivalent threshold sound pressure level function of the target in-ear headphone is obtained. The steps include: obtaining the headphones at multiple standard discrete frequency points. Pure tone reference equivalent threshold sound pressure level data ; For the discrete data Interpolation is performed to obtain the pure tone reference equivalent threshold sound pressure level function at continuous frequencies. .

5. The method for calculating the equal loudness level curve of a plug-in earphone according to claim 4, characterized in that, The interpolation process employs linear interpolation, polynomial interpolation, or spline interpolation methods.

6. The method for calculating the equal loudness level curve of a plug-in earphone according to claim 4, characterized in that, The target plug-in earphone is a plug-in earphone that conforms to a preset occlusion acoustic calibration standard.

7. The method for calculating the equal loudness level curve of a plug-in earphone according to claim 1, characterized in that, In step S4, a comprehensive calculation model for the equal loudness level curves suitable for plug-in headphones is constructed, and its expression is: ， ， in, The decision was made to block the hearing threshold anchor point. This determines the nonlinear incremental trend as the loudness level increases.

8. The method for calculating the equal loudness level curve of a plug-in earphone according to claim 1, characterized in that, The comprehensive calculation model of the equal loudness level curve generated in step S4 It is configured to output in at least one of the following forms: a) by frequency and loudness level A two-dimensional data table indexed by; b) Using a specific set of loudness levels A set of equal loudness level curves with parameters; c) Calculation function interfaces integrated into the software system.

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