JP6052998B2 - Auditory temporal resolution measuring apparatus and method - Google Patents

Description

  The present invention relates to an auditory temporal resolution measuring apparatus and method for obtaining peak sensitivity and cut-off frequency of TMTF (temporal modulation transfer function) which is an index of auditory temporal resolution.

  Conventionally, there are spectral envelope information, pitch, amplitude envelope information and the like as clues for speech perception. On the other hand, in the case of sensorineural hearing loss, in addition to an increase in the minimum audible threshold, there may be a case where a frequency selectivity deterioration, a time resolution reduction, and a loudness recruitment phenomenon are observed. In particular, a decrease in temporal resolution is considered to have a large effect on speech perception.

Therefore, it is important to measure the temporal resolution of the hearing impaired. There are Gap detection threshold and TMTF (temporal modulation transfer function) in temporal resolution, but TMTF that can measure the modulation frequency and modulation degree as amplitude envelope information is more important for hearing aid application and hearing index of the hearing impaired it is conceivable that. TMTF is one of indices indicating the followability of the auditory system with respect to temporal changes in signals, and the detection threshold of the modulation degree is expressed as a function of the modulation frequency.

  TMTF is a relationship between a modulation frequency and a modulation threshold, is approximated by a first-order Butterworth filter, and is known to be expressed by two values, a peak sensitivity (peak sensitivity) and a cutoff frequency (for example, Non-patent documents 1 and 2).

Fang-Gang Zeng, Sandy Oba, Smita Grade, Yvonne Sininger and Arnold Starr, “Temporal and speech processing deficits in auditory neuropathy,” NeuroPeport 10, 3429-3435 (1999) Fang-Gang Zeng, Ying-Yee Kong, Henry J. Michalewski and Arnold Starr, “Perceptual Consequences of Disrupted Auditory Nerve Activity” J Neurophysiol 93, 3050-3063 (2005)

TMTF is thought to be effective in grasping the temporal resolution of the hearing impaired, but the conventional TMTF measurement method requires measurement of the degree of modulation at eight modulation frequencies and takes about 40 minutes. There was a problem that it was difficult to adapt to.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide an auditory temporal resolution measuring apparatus and method capable of easily measuring TMTF. It is something to try.

In order to solve the above-mentioned problem, the invention according to claim 1 is an auditory time resolution measuring apparatus for obtaining TMTF peak sensitivity A and cut-off frequency f _C representing auditory time resolution, and generates broadband noise. An inspection sound generator, a modulator that generates the inspection sound by modulating the broadband noise generated by the inspection sound generator with a predetermined frequency and a predetermined modulation degree, and an inspection that outputs the inspection sound generated by the modulator A sound output unit, a response detection unit that detects a test subject's response to the test sound output by the test sound output unit, and controls a modulation frequency and a modulation degree of the modulation unit according to the response detected by the response detection unit predetermined second degree of modulation m ₂ calculated on the basis of the first degree of modulation m ₁ and the first modulation factor m ₁ is the threshold of the degree of modulation at the first modulation frequency f ₁ is the threshold value of the modulation factor second modulated with A modulation control section for determining a wavenumber f _2, a first modulation frequency f ₁ and the modulation control unit stores data such as the first degree of modulation m ₁ and a second modulation frequency f ₂ determined storage unit presetting And a calculation unit for calculating the second modulation degree m ₂ and calculating the peak sensitivity A and the cut-off frequency f _C based on the relational expression between the data stored in the storage unit and the primary Butterworth characteristic. It is.

The invention according to claim 2 is an auditory time resolution measuring method for obtaining a TMTF peak sensitivity A representing the auditory time resolution and a cut-off frequency f _C , and the test sound modulated at the first modulation frequency f ₁ The first modulation degree determination step for determining the first modulation degree m ₁ at which the subject's response is not detected, and the second modulation degree m ₂ calculated based on the first modulation degree m ₁ The second modulation frequency determining step for determining the second modulation frequency f ₂ at which no response is detected, and the peak sensitivity A is calculated from the first modulation degree m ₁ determined in the first modulation threshold value determining step and the first A calculation step of calculating a cutoff frequency f _C from the modulation degree m ₁ , the second modulation degree m ₂ and the second modulation frequency f ₂ is provided.

In the calculation step, the cutoff frequency f _C can be calculated from the mathematical formula: m ₂ = m ₁ · [1+ (f ₂ / f _C ) ² ].

According to the present invention, the TMTF peak sensitivity A and the cut-off frequency f _C representing the temporal resolution of hearing can be easily obtained in a short time.

Configuration diagram of an auditory temporal resolution measuring device according to the present invention It is explanatory drawing of test | inspection sound, (a) is white noise, (b) is a modulation signal and an amplitude modulation wave Example of curve approximating TMTF

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, an auditory time resolution measuring apparatus 1 according to the present invention includes an inspection sound generator 2, a modulation unit 3, an inspection sound output unit 4, a response detection unit 5, a modulation control unit 6, a storage unit 7, A calculation unit 8 and an output unit 9 are provided.

The inspection sound generator 2 generates broadband noise such as white noise that forms the inspection sound. The modulation unit 3 modulates the white noise generated by the inspection sound generation unit 2 with a predetermined modulation frequency and a predetermined modulation degree, and outputs it to the inspection sound output unit 4 such as a speaker.

The response detection unit 5 includes a push button switch that is continuously pressed when the subject who has heard the test sound output from the test sound output unit 4 feels modulation, and is released when the test no longer feels modulation. The operation of the push button switch can be determined according to the specifications.

The modulation control unit 6 controls the modulation frequency and modulation degree set in the modulation unit 3. The storage unit 7 stores a predetermined modulation frequency and a predetermined modulation degree in advance, and stores data such as a measured or calculated modulation degree and modulation frequency, peak sensitivity, and cutoff frequency.

The calculation unit 8 calculates peak sensitivity, a cutoff frequency, and the like using data and measurement results stored in advance in the storage unit 7. The output unit 9 is a monitor or printer that displays TMTF measurement results, an external storage medium that stores TMTF measurement results, and the like.

The operation of the auditory time resolution measuring apparatus 1 according to the present invention configured as described above and the auditory time resolution measuring method according to the present invention will be described. A first modulation frequency f ₁ (for example, 8 Hz) and an initial value m ₀ (m ₀ ≦ 1, for example, 0.9) of the modulation degree are stored in advance in the storage unit 7.

First, the modulation degree increases and decreases depending on the response of the subject is detected with respect to test sound modulated by the first modulation frequency f _1, to determine a first modulation factor m ₁ in which the subject's response is no longer detected (first Modulation degree determination step).

In the first modulation degree determination step, first, the white noise N generated by the inspection sound generating unit 2 shown in FIG. 2A is used as a carrier signal from the inspection sound output unit 4 such as a headphone or a speaker, and this carrier signal is used as the modulation unit. 3 is modulated with the first modulation frequency f ₁ (for example, 8 Hz) and the initial value m ₀ (for example, 0.9) of the modulation degree m, and the inspection sound shown in FIG. Here, the modulation degree m is the ratio As / Ac of the amplitude As of the modulation signal and the amplitude Ac of the carrier signal.

When the subject who has heard the inspection sound output from the inspection sound output unit 4 feels modulation, the subject continues to press the push button switch (there is a response). The modulation control unit 6 gradually decreases the modulation degree m from the initial value m ₀ until the subject's response disappears.

Then, the modulation control unit 6 repeats gradually increasing the modulation degree m when there is no response, and gradually decreasing the modulation degree m when there is a response again. When it falls within the range, the median value of the change width of the modulation degree m is calculated and stored in the storage unit 7 as the first modulation degree m ₁ .

In addition, the threshold value of the modulation factor m is measured not only by the method of measuring the threshold value of the modulation factor m by continuously increasing / decreasing the modulation factor m as described above but also by a method according to the ascending method or the descending method in hearing measurement. May be.

Next, according to the response of the subject detected with respect to the test sound modulated at the predetermined modulation frequency at the second modulation factor m ₂ calculated based on the first modulation factor m ₁ determined in the first modulation factor determination step. to increase or decrease the modulation frequency to determine the second modulation frequency f ₂ which the subject's response is no longer detected (second modulation frequency determination step).

In the second modulation frequency determination step, first, peak sensitivity A (dB) is calculated by the calculation unit 8 using the formula: A = 20 log (m ₁ ) and stored in the storage unit 7. Further, the calculation unit 8 calculates the square root of the first modulation degree m ₁ (A is a true number with which A is ½), and stores the value in the storage unit 7 as the second modulation degree m ₂ .

This calculation is not limited to the square root, and may be any condition that satisfies m ₁ <m ₂ <1. Therefore, the calculation is not limited to half of peak sensitivity A, and corresponds to a value greater than peak sensitivity A. It may be set as appropriate.

Then, the modulation control unit 6 sets the second modulation degree m ₂ in the modulation unit 3 and gradually increases the modulation frequency of the modulation unit 3 from the first modulation frequency f ₁ . Similarly to the measurement of the first modulation degree m _1, the frequency at which the modulation is not felt is measured and stored in the storage unit 7 as the second modulation frequency f ₂ .

Next, a cutoff frequency f _C is calculated from the first modulation degree m ₁ , the second modulation degree m ₂ and the second modulation frequency f ₂ (calculation step).

In the calculation step, a first-order Butterworth characteristic curve that passes through two points (m ₁ , f ₁ ) and (m ₂ , f ₂ ) is calculated, and a cut-off frequency f _C is calculated. For example, the calculation unit 8 calculates the cutoff frequency f _C from the mathematical formula: m ₂ = m ₁ · [1+ (f ₂ / f _C ) ² ].

Next, as shown in FIG. 3, the relationship (TMTF) between the modulation frequency and the modulation degree that can be perceived is approximated using the peak sensitivity A (dB) calculated in the calculation step and the cut-off frequency f _C (Hz). The curve is estimated and displayed by the output unit 9 such as a monitor or a printer.

According to the present invention, at the first modulation frequency f ₁ set in advance, the modulation degree m is increased or decreased according to the response of the subject, the first modulation degree m ₁ is measured, and then obtained based on the first modulation degree m _1. and since the second degree of modulation m ₂ to increase or decrease the modulation frequency according to the response of the subject to measure a second modulation frequency f _2, the first degree of modulation m ₁ at the first modulation frequency f _1, the second degree of modulation TMTF can be estimated from two measurement points of the second modulation frequency f ₂ at m ₂ .

The present invention is an auditory temporal resolution measurement capable of obtaining a peak sensitivity A (dB) and a cut-off frequency f _C (Hz) of TMTF (temporal modulation transfer function) representing the temporal temporal resolution easily in a short time. An apparatus and method are provided.

DESCRIPTION OF SYMBOLS 1 ... Auditory time resolution measuring device, 2 ... Examination sound generation part, 3 ... Modulation part, 4 ... Examination sound output part, 5 ... Response detection part, 6 ... Modulation control part, 7 ... Memory | storage part, 8 ... Calculation part, 9: Output unit.

Claims (3)

An auditory time resolution measuring device for obtaining TMTF peak sensitivity A and cut-off frequency f _C representing auditory time resolution, and an inspection sound generator for generating broadband noise, and the inspection sound generator A modulation unit that generates a test sound by modulating broadband noise with a predetermined frequency and a predetermined modulation degree, a test sound output unit that outputs a test sound generated by the modulation unit, and a test output by the test sound output unit A response detection unit for detecting a response of the subject to the sound, and the modulation frequency and the modulation degree of the modulation unit are controlled according to the response detected by the response detection unit, and the modulation degree at the predetermined first modulation frequency f ₁ is set. the second degree of modulation m ₂ and a modulation control section for determining a second modulation frequency f ₂ which is a threshold value of the modulation degree first calculated based on the modulation index m ₁ and the first modulation factor m ₁ is a threshold value set in advance A storage unit in which the first modulation frequency f ₁ and the modulation control unit stores data such as the first degree of modulation m ₁ and a second modulation frequency f ₂ determined that the to calculate the second degree of modulation m ₂ An auditory temporal resolution measuring apparatus comprising: a calculation unit that calculates peak sensitivity A and cutoff frequency f _C based on a relational expression between data stored in a storage unit and primary Butterworth characteristics. A method for measuring auditory time resolution for obtaining TMTF peak sensitivity A and cut-off frequency f _C representing auditory time resolution, and detecting a response of a subject to a test sound modulated at a first modulation frequency f ₁ a first modulation level determining step of determining a first modulation index m ₁ no longer is, the first relative modulation m second modulation m ₂ calculated on the basis of the ₁ response in a subject no longer detected second modulation A peak sensitivity A is calculated from the second modulation frequency determination step for determining the frequency f ₂ and the first modulation factor m ₁ determined in the first modulation threshold value determination step, and the first modulation factor m ₁ and the second modulation factor are calculated. An auditory temporal resolution measuring method comprising a calculating step of calculating a cutoff frequency f _C from the degree m ₂ and the second modulation frequency f ₂ . 3. The auditory temporal resolution measuring method according to claim 2, wherein in the calculation step, a cutoff frequency f _C is calculated from a mathematical formula: m ₂ = m ₁ · [1+ (f ₂ / f _C ) ² ]. A method for measuring temporal resolution of auditory characteristics.

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