JPH0310280B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to hearing aids. Hearing aids, to put it simply, amplify sound, and are basically equipped with a microphone,
It consists of an amplifier and earphones. Some use a bone conduction receiver as a transducer instead of earphones, while others use a bone conduction receiver that contacts the stirrup bone, as is the case with implantable middle ear and cochlear implants, which have been attracting attention recently. Some devices use a vibrator, or a needle electrode inserted into the cochlea; all of these are collectively referred to as hearing aids.

[Background technology and its problems]

Although hearing aids are said to amplify sound, they also have various additional functions and process sound signals in various ways. By the way, in conventional hearing aids, among the factors that make up sound, attention is paid to frequency and level, and these are processed. For example, in terms of frequency characteristics, high-pitched sounds are amplified in particular, and an output limiting device is installed to prevent the sound level from exceeding the discomfort threshold, making adjustments as appropriate to suit the hearing ability of the hearing-impaired.

Generally, people with hearing loss have a narrower dynamic range of hearing than people with normal hearing, although this varies depending on the degree of disability. In this case, the dynamic range usually refers to the value obtained by subtracting the minimum audible threshold (hereinafter referred to as HTL) from the discomfort threshold (hereinafter referred to as UCL).
UCL refers to the intensity at which a sound cannot be heard, and HTL refers to the minimum level at which a sound can be heard. UCL is 100-110dB for normal hearing people
HL (measured with an audiometer), in people with hearing loss
Almost distributed between 110 and 120 dB HL. Therefore, the auditory dynamic range for a moderately hearing-impaired person with an HTL of 70 dB HL is 120 dB - 70 dB = 50 dB, and if you use an ordinary hearing aid and adjust it so that the audio information falls within the dynamic range, you will be able to hear it sufficiently. It becomes possible to understand conversations. however
For people with severe hearing loss whose HTL is 100dB HL to 110dB HL, this dynamic range of hearing is
The range is 120 dB - 100 dB (or 110 dB) = 20 dB (10 dB), and even if the level is amplified with a hearing aid, it is impossible to understand all conversation sounds. In other words, for vowels, the difference between the effective value level and the peak factor is 15 dB to 20 dB, so most of the time you only hear the peak factor part, and for consonants, the energy is about 15 dB compared to vowels. Syllable intelligibility is quite poor due to the low ~30 dB. Furthermore, if the level of conversational sounds becomes even slightly lower, the amount of audio information above HTL will decrease by that amount, further worsening syllable intelligibility.

As mentioned above, conventional hearing aids have not been able to adequately respond to the poor hearing caused by the narrow dynamic range of people with hearing loss, especially those with severe hearing loss.

In contrast, the present inventors have previously filed a patent application for an invention that focuses on time information of audio signals (filing date: January 25, 1985, title of invention: hearing aid). The present invention is deeply related to the previous invention.

[Purpose of the invention]

The present invention is intended to change the conventional way of hearing aids, which solve poor hearing using only sound level information.

That is, the present invention adds not only the level information of the voice but also the time information of the voice signal by converting the voice wave into a rectangular wave series waveform as time passes, thereby providing relatively clear information to hearing-impaired people with a narrow dynamic range. The purpose is to convey as much audio information as possible without sacrificing quality.

Of course, the audio level information referred to in the present invention is not obtained from conventional analog information, but is obtained by creating a staircase waveform of a rectangular wave series divided into n pieces.

[Summary of the invention]

In order to achieve the above object, the present invention slices an audio waveform into n different levels, converts each level into a rectangular wave series waveform to obtain time information, and further converts the audio waveform into a rectangular wave series waveform at each level. By adding the series waveforms, it is converted into a staircase wave to obtain audio level information.

[Embodiments of the invention]

FIG. 1 shows one embodiment of the present invention, and FIG. 2 is a time chart obtained for each section of FIG. Incidentally, in FIG. 2, the time relationships of the audio wave, the rectangular wave, and the staircase wave are the same.

A microphone 1 converts an audio signal from a sound wave to an electrical signal, and an amplifier 2 amplifies it to a predetermined level to obtain an audio signal wave A. This audio signal wave A is then detected by a side detector 3 and a side detector 4 to obtain audio detected waves B and C, respectively. Of these, the audio detection wave B is given to one of the two input terminals of the n comparators 5, and the audio detection wave C is given to one of the two input terminals of the n comparators 6 of the other channel.
are applied to one of the two input terminals. The other input terminal of each comparator 5, 6 has
A comparison voltage is applied from the reference voltage generator 7, and when the absolute value of the audio detection waves B and C becomes larger than the comparison voltage, the output becomes the "1" level, and when it becomes smaller, the output becomes the "0" level. present. That is, the audio signal wave is converted into a rectangular wave series waveform as time passes. The comparison voltage is generated as a DC reference voltage by a reference voltage generator 7, applied to an attenuator 8, divided into n parts, and applied to a comparator 5 in descending order of level.
It is given to the other input terminal of a, 5b, 5c, . . . 5n. The DC reference voltage is supplied to the attenuator 9 after being phase-inverted by a phase inverter 10 and converted into a voltage, which is then divided into n and input to the other inputs of the comparators 6a, 6b, 6c, . . . 6n in order of the largest absolute value. given to.

Note that the DC reference voltage generated by the reference voltage generator 7 is converted into a desired voltage by the attenuators 8 and 9. means the slicing voltage for slicing, and when the audio signal waveform B exceeds the slicing voltage, the output of the comparator 5 is
Maintains a constant level in the direction, and maintains zero level below. Further, when the audio signal waveform C becomes less than or equal to the slice voltage, the output of the comparator 6 maintains a constant level in the direction, and when it exceeds the slice voltage, it maintains a zero level.

Therefore, the function of the attenuators 5 and 6 in this case is that when listening to conversational sounds in a place with a lot of extraneous noise, slicing at a level higher than the noise level removes the extraneous noise and eliminates only the voice information. to increase the signal-to-noise ratio. In a place with little external noise, the slice level is lowered to near zero, thereby controlling the function of obtaining as much audio information as possible and improving clarity.

Next, the relationship between the attenuators 8 and 9 and the comparators 5 and 6 will be specifically described. For example, n = 4, maximum voltage of audio detection wave = e _1nax , reference voltage = e _2nax ,
Under the condition of e _1nax = e _2nax , in the attenuator 8, the reference voltage applied to the comparator 5a = -
Attenuation characteristics with the following relationships: 10 dB・e _1nax , reference voltage applied to comparator 5b = −20 dB・e _1nax , reference voltage applied to comparator 5c = −30 dB・e _1nax , reference voltage applied to comparator 5d = −40 dB・e _1nax Then, the signal obtained by slicing 40 dB of audio level information in steps, that is, the comparator 5 receives rectangular wave series waveforms Da and D, respectively.
Db, Dc, and Dd are obtained. The channels operate in the same manner, and the comparator 6 obtains rectangular wave series waveforms Ea, Eb, Ec, and Ed, respectively.

The outputs of comparators 5 and 6 are the lowest level comparators 5d and 6d (nth comparator)
The signals except for 1 are applied to an adder 13 via attenuators 11 and 12, respectively, and are added to obtain a staircase waveform F. At this time, the amount of attenuation of attenuators 11 and 12 is 0.
In this case, since all the same levels are added, the level difference on the staircase of the summed waveform will rise at double intervals, that is, every 6 dB, and will have a dynamic range of 18 dB. Similarly, if the amount of attenuation is 1/2, the staircase waveform will look like G,
The relationship is 1, 1.5, 2, 2.5, resulting in a dynamic range of 7.96 dB. By changing the values of the attenuators 11 and 12 in this manner, the dynamic range of the output can be freely changed without changing the amount of audio level information set by the attenuators 8 and 9.

The reason why the attenuators 11 and 12 are not inserted into the lowest level comparators 5d and 6d is that if the output level is controlled in the same way as the other comparators 5a to 5c and 6a to 6c, all of them will be at twice the level as described above. As you can see, the level can only be changed in size, but the dynamic cleanse will not change. In other words, raise the lowest level
Raise it to the HTL level, then adjust the other comparator 5a according to the dynamic range of hearing.
By changing the output levels of ~5c and 6a~6c, the dynamic range of the output wave can be freely changed.

The staircase waveform F or G is power-amplified by a power amplifier 15 via an attenuator 14, and is applied to a receiver 16 where it is converted into a sound wave. The attenuator 14 is used to appropriately adjust the level according to the hearing threshold of a hearing-impaired person.

By the way, the number of divisions and the division ratio of the attenuators 8 and 9 are determined by how many dB of dynamic range of the audio signal is required.The larger the number of divisions, the higher the level resolution, and the smaller the division ratio, the higher the level resolution. It gets expensive. However, no matter how large the number of divisions is, if the division ratio is small, the resolution will be high;
This means that the amount of audio information decreases, and by increasing the number of divisions and making the division ratio equal, the resolution increases and the amount of audio information increases. Furthermore, the division ratio refers to the damping ratio of one step above or below.

〔Effect of the invention〕

As described above, the present invention processes audio waveforms to simultaneously provide audio time information and level information to people with severe hearing loss who have a narrow auditory dynamic range, without comparably impairing intelligibility. You can hear conversation sounds. In other words, experimentally, syllable intelligibility can be obtained by approximately 65% with only the zero cross wave (in the example, a rectangular wave series waveform approximately equivalent to the nth comparator output wave), and approximately 90% in sentence intelligibility. It has been confirmed that this can be done, but since it is basically a square wave, the sound will be noisy. Therefore, as in the present invention, by adding n pieces of level information of the rectangular wave series, the sound quality is further improved and at the same time, the clarity is further improved, and the effect is remarkable. The present invention is particularly suitable as a hearing aid for people with severe hearing loss.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.
FIG. 2 is a time chart showing waveforms of various parts of the embodiment. 3, 4: Detector, 5, 6: Comparator, 7:
Reference voltage generator, 8, 9: Attenuator, 10: Phase inverter, 11, 12: Attenuator, 13: Adder, 1
4: Attenuator.

Claims (1)

[Claims] 1. A means for slicing an audio waveform into n different levels and converting each level into a rectangular wave series waveform to obtain time information; and summing the rectangular wave series waveforms at each level. A hearing aid comprising means for obtaining sound level information, possibly by converting it into a staircase wave. 2 When adding the rectangular wave series waveforms of each level,
Claim 1 characterized in that by appropriately changing the level of each rectangular wave series waveform, the dynamic range at the time of output can be changed to a desired value.
Hearing aids listed in section.