Bioacoustic Concept Bioacoustics comes from the words bio and acoustics. Bio means life and acoustics means the study of vibrations and sound. Bioacoustics are mechanical changes in a gas, liquid, or solid that often give rise to sound waves. Bioacoustics is the study of the hearing process produced by living organisms, because these sound waves are vibrations of molecules colliding with each other, but these substances work together to produce waves. 1. Sound Sound waves are vibrations or movements of substance molecules that collide with each other where the substances are coordinated to produce waves and transmit energy without particle movement. a. Sound Source Sound sources are all objects that vibrate and produce sound that travels through a medium or intermediary substance to the ear. Examples of sound sources are: burning oil in an engine, musical instruments, movement of tree branches, bells, tuning forks, etc. The conditions for sound to occur are: a) There is a vibrating sound source b) There is an intermediary substance (medium) that propagates sound waves from the source to the ear c) Vibrations have a certain frequency (20 Hz – 20,000 Hz) d) The listener's senses are in good condition b. Sound Grouping According to their frequency, sounds are grouped into: a) Infrasound (0 – 20 Hz) Infrasound is a sound that the human ear cannot hear, but can hear by crickets and dogs. This frequency is usually caused by ground vibrations, earthquakes, volcanic vibrations. b) Audiosonic sound (20 – 20,000 Hz) Audio sounds are sounds that humans can hear. Audiofrequency related to the hearing threshold value (average hearing threshold value 1000 Hz = 0 dB). c) Ultrasonic Sound (above 20,000 Hz) Ultrasonics are sounds that the human ear cannot hear. This frequency is deep The medical field is used in 3 ways, namely treatment, destructive and diagnosis. This can happen because high frequencies have quite large network penetration power. c. Sound Waves Based on the direction of propagation, waves are divided into: 1) Longitudinal waves, waves whose direction of vibration is parallel to the direction of propagation. Examples: sound gel, spring gel. 2).Transverse Waves. , waves whose direction of vibration is perpendicular to the direction of propagation. Examples: rope gel, water surface gel. Based on the mechanism, waves are divided into: 1) Mechanical waves, namely waves whose propagation speed depends on the mechanical quantity. 2) Elastic waves are waves whose propagation speed depends on the elasticity quantities. 3) Surface waves in liquids are waves whose propagation speed depends on the size of the liquid surface. 4) Electromagnetic waves are waves whose propagation speed depends on the electrical and magnetic quantities. d. Doppler effect One of the unique phenomena in acoustics is the Doppler effect. The frequency received by the listener is greater than the source frequency if the listener and source are closer to each other, and vice versa, it will be smaller if the listener and source are far away from each other. 2. Hearing System Disorders There are several disorders of the hearing system, including: a. Partially deaf (hearing impaired) This is a condition where hearing function is reduced but can still be utilized to listen and communicate with or without hearing aids. b. Total deafness (deaf) Is a condition where the hearing function is so impaired that one cannot hear and communicate even if the sound is amplified. c. Deaf conducive This is a condition where the ear cannot hear due to interference with the transmission of sound vibrations. And it can also be caused by disorders or diseases of the outer ear or middle ear. d. Sensorineural deafness (Presbycusis) This is a condition where the ear cannot hear because there is an abnormality in the cochlea, nervus VIII (auditory nerve) or the hearing center. Sensorinaural deafness is usually permanent. e. Mixed deafness Mixed deafness is a hearing loss caused by a combination of conducive deafness and sensorineural deafness. This disorder is caused by problems in the outer, middle or inner ear. f. Hearing loss due to noise (Noise Induced Hearing Loss) Hearing loss is caused by exposure to loud noise over a long period of time. The nature of this deafness is sensorineural deafness. g. Otitis media Is inflammation of part or all of the middle ear mucosa, eustachian tube, mastoid antrum and mastoid cells. 3. Health Check The use of sound waves in the health sector is in the form of diagnosis and therapy. a. Percussion method, in this method the body is considered a soundproducing drum. This method is the simplest and most conventional method. Example: patting your stomach when you are bloated or have a cold. b. Stethoscope. The flat part of the stethoscope is attached to the body to collect and pick up sound waves. Sound waves are passed through the airways until they reach the ear. The more tense the membrane, the higher the resonance frequency, so the range of sound captured will be higher. High frequency usually occurs when listen to lung sounds. Heart sounds have a lower frequency than lung sounds. c. Ultrasoundography, ultrasonic equipment has a transducer that can send sound waves as well as receive the results of the reflection of the sound waves. The Doppler effect is the basis for the use of ultrasonics, namely that there is a change in frequency due to the movement of the listener or vice versa. d. Audiometer, is a tool for measuring hearing power. The results of measuring hearing power are called audiograms. The audiometer produces sound with a certain frequency and intensity which will be given to each patient's ear to determine the limits of hearing. Meanwhile, the sound measuring instrument is called a sound level meter.