1- sound

Psychological Sound

auditory experience/actially hearing something

physical Sound

series of disturbances of molecules and moved through an elastic medium (air)

waves

The movement of molecules coming together (compressions) and then being pulled apart (rarefactions)

vibrations

cause air molecules to move (disturb them).These molecules move from the point of disturbance and move around, "hitting" other molecules. Elasticity has the original molecules bouncing back after they have moved other molecules from that position

Longitudinal Waves

Air molecules move along the same axis as the wave itself when a force is applied

-ex: sine wave

sine wave

passthrough air but are NOT seen, and no one needs to hear them

cycle

The movement of a wave consisting of its compression and rarefaction as a function of time. It is the complete sequence of events of a single sine wave through 360 degrees

frequency

-the number of complete oscillations of a vibrating body per unit of time

-measured in Hz

-cycles per second

period

time required for each cycle (= 1/frequency)

vibration/oscillation

begins at any point of the wave and ends at the identical point on the next wave.

-These are called sound waves, which are an example of sine waves

pure tone

occurs when a body vibrates showing only one frequency of vibration with no tones superimposed it is

Vibrations are affected by

energy (kinetic and potential)

- as amplitude decreases, velocity also decreases

Free vibrations

no outside force is added

lightly damped

when the vibrations of the mass decay gradually over time the system

critically damped

If vibrations stop rapidly (a single cycle is not completed)

forced vibrations (outside force)

swinging will continue until the outside force is removed and then it will go into free vibration

Effects of frequency

-As length of the wave increases the frequency decreases and as the length of wave decreases the frequency increases

-As mass increased the frequency of vibration is decreased

Resonance Frequency

the natural rate of vibration

amplitude of sound (pressure wave)

Sound Velocity

-the speed at which a sound wave travels from the source to another point.

-It is dependent on: density

Effects on velocity

-As temperature and humidity increase so does speed of sound

-At higher altitudes, the speed of sound decreases

wavelength

-measured from any point on a sinusoid (any degree from 0 to 360) to the same point on the next cycle

-W = v/f

-As frequency decreases wavelength increases and as frequency increases wavelength decreases

vowels

low in frequency = longer wavelength

consonants

high in frequency

phase

-the relationship in time between 2 or more waves

-When more than one tone is introduced, there are interactions among sound waves.

-These interactions are determined by frequency, intensity, and phase relationships.

two tones of the same frequency and phase relationship....

reinforce each other and increase the amplitude

fundamental frequency

-the lowest frequency of vibration in a complex wave

-Speech and music contain complex sounds that repeat over time.(periodic)

aperiodic sound

complex sound that varies and does not have a fundamental frequency

harmonics

in a periodic complex sound, all frequencies are whole -number multiples of the fundamental frequency

Although fundamental frequency determines all harmonics ...

The harmonics do not have equal amplitude

during speech

altering the size and shape of the vocal tract (tongue movement) will result in frequency and intensity changes that emphasize some harmonics and suppress others

harmonics and speech

Fundamental frequency no longer matters once the harmonic structure of a wave is determined.

-That is why we can determine whether it is a woman or man's voice typically over the telephone

intensity

-the amount of energy per unit of area

-Amplitude is the distance the mass moves from the rest

force

-The greater the force the greater the displacement of molecules and therefore the greater the amplitude.

-Only very small amounts of force are required to stimulate hearing

-dyne is the unit of measurement for quantifying small changes in force

pressure

-force over an area of surface so the intensity of a soundwave is the amount of force per unit of area

-Sound intensity is measured in dB, which is the ratio between 2 sound pressures (It is not a linear scale)

impedence

the opposition it gives to the transmission of acoustic energy. A surface with more density will offer more impedance to the wave

Resonance is determined by

-the mass, elasticity and frictional characteristics of an object. -Resonant characteristics are determined by impedance

intensity level

-If the intensity output and the intensity reference are exactly thesame the ratio is 1:1. Because the log of 1 is 0, the number of decibelsis 0

-0dB does not mean the absence of sound!!!!!

audiologists typically measure

sound in pressure rather than intensity terms (sound pressure level)

audiometers

test hearing sensitivity at a number of different frequencies.

Zero hearing level

-The lowest sound intensity that stimulates normal hearing

-different amounts of pressure arerequired for 0 dBHL at different frequencies

auditory threshold

The level at which a stimulus (pure tone) is barely audible.

sensation level

-the level at which the subject is just aware enough to perceive 50% of the time

environmental sounds

Normal conversation - 60dB to 70dB

Whisper - 20 dB

Pain begins - 125 dB

pitch

-subjective term for "highness" or "lowness"Range of human

-hearing (20 to 20,000 Hz)

-Intensity contributes to the perception of pitch

loudness

-the subjective experience of intensity, the duration and frequency of sounds contribute to the sensation of loudness

-changes at different frequencies

-Loudness grows faster for low - frequency tones and certain high - frequency tones than for mid - frequencies

localization

-Without knowing the source it is possible to tell the direction from which it comes

-involves interaction of both ears

depends on the relative intensities of sounds and their times of arrival at the 2 ears

ability to localize

interaural phase differences in the low frequencies and intensity differences in the high frequencies

aduioligists conduct 2 types of measurements:

1.hearing ability of patients with possible disorders of the auditory system and

2. sound pressure levels in the environment

adiometer

-used to quantify the amount of a patient's hearing loss.It generates pure tones 125 Hz through 8000 Hz

-typically calibrated 1x a year

air conduction

measured with earphones

bone conduction

measured using bone oscillator 250Hz through4000 Hz. (does not exceed 50 to 80dB)

sound level meter

-Useful to determine noise levels in industrial areas (noise pollution)

-Determine background noise levels

outer ear

pinna, ear canal and eardrum membrane

middle ear

air - filled space which contains the malleus, incus and stapes

inner ear

cochlea filled with fluids and microscopic componentswhich converts waves which travels via the 8th cranial nerve (auditory nerve)

conductive hearing loss

-causes attenuation of sound;

-hearing by air conduction is affected but bone is normal.

-On audiogram an air -bone gap is seen.

-Can be corrected by medicine or surgery.

-Loss of loudness

sensory neural hearing loss

-affected by "damage" to the inner ear or auditory nerve.

-Loss by air conduction equals loss by bone conduction.

-Loss of clarity.

-The term deaf implies very little residual hearing

mixed hearing loss

-Deficits in both the conductive andsensory/neural mechanisms.

-Deficit in air conduction is greater than loss in bone conduction.

-Air bone gap is present

central hearing loss/ auditory processing disorder

-a decrease in auditory comprehension regardless of language or cognitive abilities and in the absence of any measurable deficit of air or bone -conduction levels.

processing difficulties affect

-sound processing, discrimination, memory, and sequencing which would also affectauditory - based learning or social participation

non organic hearing loss

-possibly faking a hearing loss for financialor other gain (malingering) or because a psychological disorder exists (psychogenic hearing loss_

Tuning for test

-cannot tell degree

- Normal hearing or equal hearing loss (cond.Sensory/neural or mixed) in both ears will report they hear in both ears

-Sensory/neural loss in one ear or different degrees of hearing loss between ears will hear it in the better ear.

-Conductive hearing loss - tone will be heard in the poorer ear

Pure tone audiometer

-used to determine hearing thresholds.

-Air conduction testing 125 Hz through 8000 Hz with range of intensity from-10 dBHL to 110 dBHL•

-Bone conduction testing from 250 Hz through 4000 Hz with intensity from about 50 dB at 250 Hz to 70/80 dB at 500 Hz and higher. It can't go higher because of harmonic distortion

considerations

-Control test environment

-Earphone attenuation devices

-Insert earphones

-Noise cancellation headphones

-Soundproof vs. sound proofed

manual pure - tone audiometry

-Patient needs to indicate when they have heard a tone. Instructions must be clear when given verbally or in writing

-Response can be: hand signal, button response, verbal response of"yes" or "I hear it"

-False positive responses "hear sounds that aren't there"

-False negative responses "don't respond when they do hear it"

air and bone conduction hearing tests

allow the examiner to determine how much hearing loss the person has and the type of loss

air conduction audiometry

-to specify the amount of a patient's hearing sensitivity at various frequencies

-It only specifies the degree of loss!!!!

-Can be affected by placement of earphones

-insert phone are more accurate and can prevent collapsed canals.

bone conduction audiometry

Purpose is to determine the patient's sensory/neural sensitivity.

3 phenomena: distortional, inertial, osseotympanic

speech detection threshold (SDT or SAT)

the hearing level at which a listener can just detect the presence of an ongoing speech signal and identify it as speech.

speech recognition threshold (SRT)

-The threshold of intelligibility ofspeech ;

-the lowest intensity at which at least 50% of a list of spondees can be identified correctly.

-Obtained with the use of spondaic words (2 syllables with equal stress).

relationship between SRT and PTA

-Often depends on the configuration of the audiogram

-Can be useful in comparing to PTA to signal accuracy of both tests

speech recognition testing

-Measure of percentage

-Can be obtained with and without visual cues

-Used a lot in hearing aid counseling

-Uses phonetically balanced word lists

-given 25 words @50 dB (normal hearing repeats back 23 words)

Most Comfortable Loudness Level (MCL)

level for listening to speech comfortably

Uncomfortable Loudness Level (UCL)

the level at which sound becomes uncomfortably loud for a listener - can use cold running speech to program hearing aids

dynamic range

the arithmetic difference between a threshold measure and the UCL for the same signal

-want and larger DR