JP7220444B2 - Acoustic transmission system - Google Patents

Description

TECHNICAL FIELD The present invention relates to an acoustic transmission method, and more particularly to an acoustic transmission method using bone conduction.

The sound transmission method by bone conduction is perceived as a clear sound even by people with conductive hearing loss, does not block the external auditory canal, is easy to hear even in noisy environments, and is perceived as a clear sound even at high frequencies (ultrasonic waves) of 20 kHz or higher. etc. In particular, bone-conducting ultrasound can be perceived by people with severe sensorineural hearing loss, and it is possible to transmit sound and frequency information by amplitude modulation. sonic hearing aids) have been developed.

For example, Patent Literature 1 discloses an external sound perception device configured to transmit ultrasonic signals from a plurality of transducers based on an external sound input to a microphone. Each vibrator can be attached near the mastoid process by a gimbal mechanism.

In this way, conventional bone conduction hearing aids are generally used by pressing the vibrator against the mastoid process of the human head. It could not be obtained, and there was a risk of causing pain. Moreover, when a hair band or the like is used to securely attach the vibrator to the head, there is a cosmetic problem, which hinders the spread of the device.

Japanese Patent Application Laid-Open No. 2004-343302

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sound transmission system that solves the problems of wearability and beauty.

The object of the present invention is to provide a bone conduction vibrator in a contact portion that functions in contact with a part other than the head of a human body, thereby transmitting acoustic information from the bone conduction vibrator to a part other than the head of the human body. A system, wherein the acoustic information is obtained based on a vibration signal generated by modulating a carrier signal with a sound signal, the frequency of the carrier signal is set in a range of 20 kHz to 100 kHz, and the acoustic information is : Accomplished by an acoustic transmission method presenting to any of the triceps , brachii, biceps and brachioradialis muscles.

According to the sound transmission system of the present invention, the wearability and cosmetic problems can be resolved.

1 is a schematic configuration diagram of an acoustic transmission device for performing the acoustic transmission method of the present invention; FIG. 2 is a block diagram of the acoustic transmission device shown in FIG. 1; FIG. 1. It is a figure which shows an example of the experimental result using the sound transmission apparatus shown in FIG. FIG. 8 is a diagram showing another example of experimental results using the acoustic transmission device shown in FIG. 1; It is a figure which shows an example of the measurement result of the auditory evoked brain magnetic field.

The present invention will now be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an acoustic transmission device to which the present invention is applied, and FIG. 2 is a block diagram thereof. As shown in FIGS. 1 and 2, the acoustic transmission device 1 includes a vibration signal generation unit 10 that generates a vibration signal, and a vibration transmission unit 20 that transmits mechanical vibration based on the vibration signal to the outside as acoustic information. I have.

The vibration signal generation unit 10 includes a sound signal generation unit 12 that generates a sound signal, a carrier signal generation unit 14 that generates a carrier signal, and an input that can adjust the frequency, waveform, amplitude, timing (phase), etc. of the carrier signal. and a carrier signal modulator 18 that modulates (for example, amplitude modulates) a carrier signal based on the sound signal generated by the sound signal generator 12 to generate a vibration signal.

The sound signal generation unit 12 is composed of, for example, a microphone or the like, and generates sound signals by detecting and amplifying sounds from the outside. The sound signal generator 12 may be an audio device or the like that reproduces a pre-recorded sound signal. Examples of sound signals include sine waves, rectangular waves, triangular waves, voices, musical instrument sounds, and environmental sounds of 100 Hz to 10 kHz.

The input unit 16 includes a volume switch capable of continuously changing the frequency, amplitude, phase, etc., a signal waveform switching switch, and the like. The frequency of the carrier signal generated by the carrier signal generator 14 can be an audible range of 50 Hz to 20 kHz, or an ultrasonic wave of 20 kHz to 100 kHz. Also, the waveform of the carrier signal can be a sine wave, a square wave, a triangular wave, or the like, or can be a composite wave having the fundamental frequency of the above audible range or ultrasound.

The vibration transmitting portion 20 includes a bone conduction vibrator 22 housed in a casing-shaped contact portion 21 and a mounting portion 24 made of an elastically deformable rubber band fixed to the contact portion 21 . The vibration transmitting section 20 is configured such that the contact section 21 is brought into contact with the neck, the upper trunk, the upper arm, the forearm, or the like, and the mounting section 24 is wound, and hook-and-loop fasteners 24a and 24b at both ends of the mounting section 24 are engaged with each other. By aligning them, the bone conduction vibrator 22 can be fixed to a part of the human body other than the head.

The present inventors conducted an experiment to confirm whether or not acoustic information can be transmitted to a subject using the acoustic transmission device 1 described above when bone-conducted sound is presented to a distal area other than the subject's head. Figure 3 is an example of the test results when the carrier signal is an ultrasonic wave. It shows the relative discrimination threshold at each presentation position when the bone conduction transducer 22 is fixed. Based on the mastoid process, which is the mounting position of a conventional general bone conduction transducer, the value of the relative discrimination threshold increases as the presentation position moves away. has been shown to be audible. When the carrier signal was an ultrasonic wave, it was possible to selectively transmit acoustic information only to the subject without causing sound leakage to the surroundings of the subject.

FIG. 4 shows the results of measuring the detection threshold for the presence or absence of modulation as the degree of modulation when the ultrasonic carrier signal is amplitude-modulated at various modulation frequencies. When the bone conduction transducer 22 is attached to the mastoid, sternocleidomastoid (neck), triceps brachii, brachial, biceps brachii, and brachioradialis (forearm), any presentation It was confirmed that the degree of modulation can be detected even at the position and that the modulation information can be transmitted.

The sound transmission system of the present invention is based on the above findings. It is characterized by transmitting acoustic information other than.

The contact part has a unique function when used by the user, and is not particularly limited as long as it is inevitably contacted by a part other than the head of the human body in order to perform the function. This sound transmission method solves the wearability and cosmetic problems that arise when a bone conduction transducer is attached to the head of the human body. Acoustic information can be provided easily and accurately.

For example, by using the armrest or backrest of a chair as the contact portion and providing the bone conduction vibrator in this contact portion, when the contact portion functions as the armrest or the backrest, the bone conduction vibrator may be transmitted from the user's elbow or the backrest. Acoustic information can be transmitted to the back.

In addition, by providing a bone conduction vibrator at a part that a user grips during use, such as a steering wheel of an automobile or a bicycle, or a grip part of a microphone, etc., as the contact part, the contact part can be Acoustic information can be transferred from the bone conduction transducer to the user's finger or palm when functioning.

In addition, according to the sound transmission method of the present invention, a bone conduction vibrator can be provided on the edge of a desk to transmit acoustic information to the user's wrist or forearm, or a bone conduction vibrator can be provided on an accessory such as a necklace. Transmitting acoustic information to the user's neck, arms, etc., transmitting acoustic information to the user's trunk, etc. by installing a bone conduction transducer in bedding such as a mattress, and transmitting bone conduction to a pillow, helmet, etc. It is possible to transmit acoustic information to the user's neck by providing a vibrator, and it can be applied to a wide range of products and equipment.

Acoustic information to be transmitted to the user is obtained by a vibration signal generated by amplitude-modulating a carrier signal with a sound signal in a configuration similar to that of the acoustic transmission device 1 described above. , the acoustic information can be accurately presented only to the user of the contact portion.

However, since high-frequency sounds are generally attenuated over distance, it is necessary to improve the quality of acoustic information transmission from a distance by ensuring that sufficient energy reaches the inner ear, where the auditory receptors are located, from the presentation site. The frequency is preferably 20 kHz to 40 kHz, which is low in the ultrasonic range.

FIG. 5 is a diagram showing the results of measurement of auditory evoked brain magnetic fields when bone-conducted ultrasound stimulation was presented to the mastoid. When the induced brain magnetic field was measured by changing the frequency of the carrier signal modulated by a 1 kHz tone burst, the response (N1m) was evoked even though the input voltage at each frequency was kept constant. activity intensity (ECD moment) changes. A clear N1m response is observed at any frequency, but the strongest activity is obtained especially around 27 kHz.

Since this tendency is presumed to be the same when acoustic information is presented to parts other than the head of the human body, it is preferable that the frequency of the carrier signal is set to 20 kHz to 40 kHz in the acoustic transmission system of the present invention. It is more preferable to set it to 21 kHz to 33 kHz, and even more preferably to set it to 24 kHz to 30 kHz.

The waveform of the carrier signal is not particularly limited, but a sine wave is particularly preferred. Acoustic information is presented at bony prominences such as the clavicle, acromion, medial epicondyle, lateral epicondyle, radial head, condylar radial styloid process, and ulnar styloid process, as well as the sternocleidomastoid muscle of the neck, and the sternocleidomastoid muscle of the chest. Larger muscles such as the pectoral muscles, back trapezius, deltoids, lats, brachii muscles, and brachioradialis are good.

1 Acoustic transmission device 10 Vibration signal generation unit 20 Vibration transmission unit 21 Contact unit 22 Bone conduction transducer

Claims (1)

An acoustic transmission method for transmitting acoustic information from the bone conduction vibrator to a part other than the head of the human body by providing a bone conduction vibrator in a contact portion that functions by contacting with a part other than the head of the human body,
The acoustic information is obtained based on a vibration signal generated by modulating a carrier signal with a sound signal,
setting the frequency of the carrier signal in the range of 20 kHz to 100 kHz;
An acoustic transmission method for presenting the acoustic information to any one of the triceps brachii muscle, the brachial muscle, the biceps brachii muscle, and the brachioradialis muscle.

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