Phy oscillations reading material

Properties of Sound

• Sound is a mechanical wave created by vibrating bodies.
• Vibrating objects disturb surrounding air molecules, causing them to follow the object's motion.
• Adjacent molecules transfer motion, propagating the vibrational disturbance away from the source.
• Vibrations reaching the ear cause the eardrum to vibrate, creating nerve impulses for brain interpretation.
• Material medium is needed between the sound source and receiver for propagation.
• Vacuum absence, sound diminishes, becoming inaudible (bell in the jar experiment).
• Sound propagates via compressions and rarefactions of the medium, deviations in density from the average value.
• In gases, density variations equal pressure changes.
• Two key sound characteristics: intensity (compression/rarefaction magnitude) and frequency (compression/rarefaction rate).
• Frequency is measured in cycles per second, termed hertz (Hz); 1 Hz = 1 cycle per second.
• Sound patterns can be complex, but analyzing sound as simple sinusoidal vibrations is useful.
• A pure tone is a sinusoidal sound wave.
• Pressure variations in a pure tone propagating through air are sinusoidal.
• Wavelength (λ) is the distance between nearest equal points on the sound wave.
• Sound wave speed (v) depends on the material, e.g., 3.3 × 10^4 cm/sec in air (20°C) and 1.4 × 10^5 cm/sec in water.
• Relationship between frequency, wavelength, and propagation speed: v = λf.
• Pressure variations from propagating sound are superimposed on ambient air pressure;
• Total pressure: P = Pa + Po sin 2πft, Pa is ambient pressure, Po is maximum pressure change, f is frequency.
• Intensity (I) is the energy transmitted per unit time through a unit area perpendicular to propagation direction: I = P0^2 / 2ρυ with p = density of the medium and v = speed.

Properties of Waves

• Waves, including sound and light, exhibit reflection, refraction, interference, and diffraction.

Reflection and Refraction

• When a wave transitions between media, part is reflected, and part enters the new medium.
• Reflection is specular (mirrorlike) if the interface is smooth relative to the wavelength.
• Reflection becomes diffuse with irregularities larger than the wavelength.
• Refraction occurs when a wave incident at an angle changes propagation direction in the new medium.
• Reflection angle equals incidence angle; refraction angle depends on media properties.
• Energy transmitted from one medium to another depends on the properties of the media and the angle of incidence.
• For perpendicular sound wave incidence, transmitted to incident intensity ratio: It/Ii = (4ρ1v1ρ2v2) / ((ρ1v1 + ρ2v2)^2), where subscripted vars are velocity and density in the media.
• Only about 0.1% of sound energy enters water when sound traveling in air is incident perpendicular to water, 99.9% reflected, making water an efficient sound barrier.

Interference

• With multiple waves in a medium, the total disturbance equals the vector sum of individual disturbances = Interference.
• Constructive Interference: waves "in phase" add, increasing disturbance.
• Destructive Interference: waves 180° "out of phase" reduce disturbance.
• Complete cancelation occurs for equal magnitude, out-of-phase waves.
• Standing Wave: a special interference produced by identical frequency and magnitude waves traveling in opposite directions, forms in hollow pipes, existing at resonant frequencies.

Diffraction

• Waves tend to spread as they move through a medium.
• When a wave encounters an obstacle, diffraction occurs where the wave spreads into the region behind the obstacle.
• Diffraction depends on wavelength; longer wavelengths diffract more.
• Diffraction is significant behind obstacles smaller than the wavelength.
• Objects smaller than the wavelength do not produce reflection due to diffraction.
• Light and sound waves can be focused with curved reflectors and lenses.
• The focused spot diameter cannot be smaller than approximately λ/2.

Hearing and the Ear

• Hearing results from nerve response in the ear to pressure variations in sound.
• The ear is more sensitive to pressure variations than other body parts.
• The ear comprises the outer, middle, and inner ear.
• Sensory cells converting sound to nerve impulses reside in liquid-filled inner ear.
• Outer and middle ears conduct sound to the inner ear.
• Outer ear: pinna (external flap) and ear canal, terminated by the tympanic membrane (eardrum).
• The pinna in humans is fixed and small, not significantly contributing to hearing.
• The ear canal of an adult is about 0.75 cm in diameter and 2.5 cm long, resonant for sound waves around 3000 Hz, contributing to ear sensitivity.
• Sound coupling from air to inner ear fluid is inefficient unless the middle ear is used.
• Middle Ear - Air-filled cavity: contains ossicles (three bones) connecting the eardrum to the inner ear.
• Ossicles: hammer, anvil, and stirrup. The hammer connects to the eardrum, the stirrup connects to the oval window.
• Eardrum vibrations are transmitted by the ossicles to the oval window, setting up pressure variations in the inner ear fluid.
• Ossicles link to middle ear walls via muscles which act as volume control.
• These muscles stiffen during excessively loud noise reducing sound transmission.
• Middle Ear isolates the inner ear from disturbances from head movements etc.
• Eustachian Tube connects middle ear to upper throat to maintain atmospheric pressure, aided by swallowing.
• Rapid air pressure changes cause imbalances addressed by air movement through this tube.
• Cochlea - Inner Ear: The location where sound waves convert to nerve impulses.
• Cochlea description: Spiral cavity shaped like a snail shell. At the base is the oval and round windows with an area of about 4 mm². Cochlea is 2 3/4 turns.
• Uncoiled, its length would be 35mm
• Three Parallel Fluid Ducts - Cochlea Interior: shown in the simplified drawing of the uncoiled Cochlea.
• Vestibular and tympanic canals: are joined at apex of Cochlea through helicotrema
• Cochlear duct: Is isolated from the two canals with membranes.
• Basilar Membrane: supports the auditory nerves.
• Vibrations to the oval window set up vibrations that are sound waves; wave is setup in vestibular canal fluid
• Travels along its canal AND helicotrema into the tympanic canal
• The basilar membrane vibrations encourage auditory nerves to transmit electric pulses to the brain.
• Motion by tympanic canal dissipates excessive wave energy

Performance of the Ear

• Nerve impulses evoke subjective sound sensations in the brain.
• Loudness, pitch, and quality are terms for describing sounds.
• Relating subjective responses to physical properties (intensity, frequency) is a challenge.
• Most instrument and voice sounds are complex with each having its characteristic pattern.
• J.B.J Fourier determined complex wave shapes can be organized into sinusoidal waves.
• A complex wave pattern can be constructed adding sinusoidal waves at given amplitudes and frequencies.
• Lowest frequency in the waveform is a fundamental with higher frequencies called harmonics.
• Harmonic content differentiates sound source

Frequency and Pitch

• The human ear frequency ranges from 20 to 20,000Htz.
• The ear doesn't have uniform range, it's most sensitive at 200-4000htz and responsiveness reduces at higher and lower frequencies.
• Some people cannot see above 8000htz while others above 20,000htz
• Hearing degrades with age.
• Pitch of sound is equivalent to its frequency with middle C is at 256htz and the A above at 440htz
• Relationship through math is absent with pitch and frequency.

Intensity and Loudness

• Ear responds to intensities (Enormous) with 3000htz
• EAr hears 10^-16w/cm lowest tolerable intensity.
• Around 10^-4w/cm is highest.
• Threshold and intensity ranges refers to threshold of pain and intensity loudness
• Permanent Damage: Can inflict to eardrums by threshold of pain intensities.
• Million linear responses are not available with ear (sound intensity wise) sound isn't million louder linear.
• Response to ear and intensity are closer to logarithmic.
• The nonlinear ear and intensity ranges involve in hearing conveniently.
• Measurement to intensity scale is the Sound Intensity level is 10^-16w/cm approximately.
• Measurement to decibels Log Intensity = 10x Log -Sound Intensity 10^-16
• Log 10 =40DB is log sound through of 10^-12
• Refer and look sound via table.
• Table :Log algorithm responds into sound Intensity (believed at a low pace.)
• Table Log sound to busy street to only sound log rhythm pace.
• Ear Response is shown NOT logarithmic.
• Intensity of logarithm response is clear.
• Sensitivity that is 200-300 htz sound intensity 10*-015 and variation of sound wave at 2.9 *10^-04
• Atmospheric pressuring is around I 10^

Bats and Echo

• Human are high auditors with developed organ levels.
• Animal are much better at ear quality and one of those animal type (notable wise
• Bats transmit sound wave high and detects from surrounding sounds from echoes.
• Hearing level is acute to the point that you can obtain from the echoes.
• Species of bats get echoes in given way.
• Family is Verpertilionidae and they let out trill sounds at 3*10^-3 intervals at 70msec
• Each trill ranges to 10010^3 and fall from 3010^3 at end.
• Ears are receptive to High ranges.
• Intermission is from a bat range to detect a weak echo (non interference wise)
• Interval in frequency to object determine distance.
• 70 Msec from object ( 11.5 range)
• Short range = object range shortens ( durations shortens)
• 5 msec range ( object range)
• Echoloation show animal avoids wire with diameter of 0.1mm, but fail to finer objects.
• Other animals such as porpoises, whales and some birds detect and use echoes.

Produces Sound Via Animals

• Way Sound are made through various way with insects rubbing wings.
• Rattlesnake create its sounds with tail shakes.
• Human Vocal cords and voice are shown.
• Cords are two reeds/ shaped by lips attach to trachea upper.
• Cords open and breathe
• Cords edge brings sounds.
• Lungs pass edge space cords bring vibration
• Frequency determine with cords tensions
• Averages voice with males and 140msec Females around 230
• Tongue creates most of finality
• Out Side through consonants.

Acoustic Traps

• Sound is created to mimic insects/ animals with lures and Traps.
• Fish and lure is used with lures of mackerel and attraction of marlin.

Ultrasonic Waves

• Baseline of populations determine bats via examines etc.
• Study to Socials rare study sound.
• South east area: Synthesis bat to land nets.

Clinical Uses

• Analysis use to tools and machines with stethoscopes
• bell cavity attach to hallow tube that is flex.
• The bells sit via skin above body sound.
• Organs functioning are shown through tool uses.
• Modified versions are two bells that detect parts of body zones and areas.

Ultrasonic Waves

• Mechanical waves are created through cycle and high cycles.
• Frequencies is expanded via cycle ( ultrasonics levels)
• Waves are to be shown via areas for exercises.
• Ultrasonic has specialized imaging.
• Tissue shows absorption.
• Structures is shown to be exams safely without ultrasonic xray,
• Shows Motion and ultrasonic waves are shown to depend on how moving ( source and observes
• Observation in movement equation 12/6
• F frequency v speed and source vs
• Diathermy treatment in ultrasonic promotes healing.
• Destroy tissue thru level intense
• Kidney remove via high ultrasonic.