# Speech and Hearing #2 (chap 2)

 What is sound? Air Pressure P=F/A Pressure=Force/Area Pressure is measured in pascals/ micropascals or "dyne" Subscript denotes the type or location of the pressure. P atomsP negP trach (open=same pressure)P oral (open=same pressure) Air volume quantity of air contained ina 3-D space Air movement/ flow quantity of gas that move through a given area in a unit of time Boyles law describes relationship between pressure, and volume, and temp Pressure is high volume is high vibration/ oscillation back/ forth motin compression/rarefaction areas of high/low pressure elasticity/interia opposing forces that keep molecules in motion until acted upon by other physical law that "settle them down". sound changes in air pressure amplitude and damping frictional forces reduce the amplitude of the molecular motion thus damping the vibrations opposing forces are equal then no change interia Newton's lst law an object in motion stays in motionan object at rest stays at rest Newton's 2nd law when a net forces act upon an object the object acclerates in the same direction of the force. Accleration is directly proportional to the net force and inversely proportional to the mass F=Ma Force=Mass(acceleration) force is measured in Newtons Males have _____ vocal cords heavy, more mass Newton's 3rd law of motion for every action (force) there is an equal and opposite reaction (force) Characteristics of sound waves waveformfreq./period Hz cycles/sec more cycles more Hz, higher pitch less cycles more Hz, slower pitch transverse molecule moves perpendicular to the direction of the wave longitudinal molecule moves along the same axis as the wave sine waveform of a pure tone, graph of the vibration wavelength measured from one point on a wave to the same point on the next cycle-related to the freq. of the wave pure tone one note complex speech complex sounds are periodic or aperiodic fundamental freq. Fo measured in Hz wavelength dension of space air complex Noise Harmonic Ratio breathy the time that each cycle in a wave takes to occur is its period Human vocal folds normally vibrate between 80-500 Hz in speaking situations healthy ears low as 20 to high as 20, 000 HZ subsonic too low to be audible, may be felt ultrasonic too high to be audible 0 dB threshold of hearing 20 dB rustling leaves 30 dB conversation, sound travels faster through water "breaking sound barrier" traveling faster than speed of sound amplitude the magnitude of pressure changes in a sound and measured in micobar or micropasals the shape of a resonator is not as imporant as its volume when determining the freq to which it will resonate the vocal tract/ear canal are acoustic resonators acoustic resonator volume of air enclosed in a container can resonate sound consists of increases and decreases in air pressure caused by the movement of a source tuning fork sound waves are characterized by different dimensions of frequency, period, wavelength, amplitude, and intensity sound waves can consist of one frequency (?) and many frequencies (?) pure tone, complex waves t or f sound waves can be visually depicted on waveforms and spectra t amplitude and intensity of sounds can be measured conveniently on the decibel scale t or f t resonance involves forced vibration in which an object or container of air is set into vibration by the action of another vibration tor f t acoustic resonator may be sharply or broadly tuned, with different center frequencies and upper and lower cutoff frequencies t or f t Authorlrobert3 ID76327 Card SetSpeech and Hearing #2 (chap 2) DescriptionSpeech and Hearing #2 (chap 2) Updated2011-03-31T03:05:26Z Show Answers