Acoustic device and method of using the same

An acoustic device for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, wherein

• when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal and with a microphone that measures air-conducted sound in the artificial external ear canal, measures the air-conducted sound upon the acoustic device outputting a fundamental frequency at a predetermined frequency in an audible frequency band while placed in contact with the ear model,
• three or more harmonics at or above a sixth harmonic and exceeding a volume that is half of a volume of the fundamental frequency are measured under a second predetermined count condition.

An acoustic device for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, wherein

• when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal, a microphone that measures air-conducted sound in the artificial external ear canal, and a vibration gauge that measures vibration in the ear model, measures volume that is combined based on a value measured by the microphone and a value measured by the vibration gauge upon the acoustic device outputting a fundamental frequency at a predetermined frequency in an audible frequency band while placed in contact with the ear model,
• three or more harmonics at or above a sixth harmonic and having a volume exceeding a volume 45 dB below a volume of the fundamental frequency are measured under a first predetermined count condition.

An acoustic device for transmitting sound to a user through vibration conduction by contacting a vibrating body to a human auricle, wherein

• when a measurement system, provided with an ear model including an artificial auricle and an artificial external ear canal, a microphone that measures air-conducted sound in the artificial external ear canal, and a vibration gauge that measures vibration in the ear model, measures volume that is combined based on a value measured by the microphone and a value measured by the vibration gauge while the acoustic device is placed in contact with the ear model,
• three or more harmonics at or above a sixth harmonic and exceeding a volume that is half of a volume of a fundamental frequency are measured under a third predetermined count condition.