Hearing Science Exam 3 - MSU - Franklin

What are Beats or also know as best Beats? How are they used?

-Beat tones- 2 tones at slightly different frequency cause a fluctuation in intensity -Sounds slow down more intense/hard to tell the difference -Beats-/best beat- 2 tones only a few freq. apart causes in phase/out of-phase pattern and a beat -If 2 tones are equal in level and the frequency begins to close between the two tones the beats become louder and slower . As the 2 tones widen the beats become faster until 2 separate tones are heard. -Detectability of 2 tones (if you get them closer they become one sound and if you take them apart they become separate sounds)

Loudness

-perception of intensity - soft or loud -is the perception associated with that parameter. Measured in phons The intensity of a sound refers to its physical magnitude, which may be expressed in such terms as its power or pressure. Turning up the volume on the stereo amplifier increases the intensity of the music- this can be measured via microphone and sound level meter (SLM)

Killian (1973)

1. Ear canal resonance enhances pressure of a free field signal @ eardrum 2. Binaural-(both ears) advantage over monaurel 3. Physiological noises- heart beat, breathing- due to the occlusion effect Overall, these curves showed that human hearing is most sensitive b/w about 2000 & 5000 Hz and reasonably good sensitivity in the 100 Hz-10KHz range EARS AREN'T SENSITIVE TO CERTAIN FREQ.

What are three ways to test intensity?

1. Modulation- beats (Reisz) close to intensity of A and B, (just a few hertz) 2. Paired comparison- make judgement same or different 3. Memory judgement-problem is can't always remember

How many dB can a tenfold change in duration offset an intensity?

10 dB

Increasing the intensity of the tone lowers the pitch at what frequencies?

1000 Hz and below

What is the standard tone used in most perception measures either frequency or intensity?

1000 hz

Shifting the phase 180 degrees increases how many dB?

15 dB

What is the lowest frequency a human can perceive a tone? (feel the tone)

2 Hz

Temporal cues

2 aspects of temporal or time phenomena 1.)The actual difference in the TIME OF ARRIVAL of a sound to the two ears. Sound will reach one ear before it reaches the other ear except in those cases where the two ears are the same distance from the sound source. (Could occur in the median plane- proceeds from directly in front to directly in overhead to directly behind to directly underneath to back in front of the listener.) 2. phase differences at the 2 ears The degree to which depends on the distance between the 2 ears and the wavelength of the sound. Only sounds of low frequency, where ½ the distance of wavelengths are longer than internaural distance provide unambiguous phase cues.

Human Hearing Range

20 - 20,000 Hz

What is the lowest frequency a human can hear a tone?

20 Hz

increasing intensity of a tone increases the pitch for what frequencies?

3000 Hz and above

How many Mels is 20,000 Hz?

3500 Mels

80 phons is equal to ___________ dB at 1000 Hz

80db?

How many dB does it take to double in loudness? What is the lowest frequency we can perceive as a "tone"?

9 dB-double 2dB is the lowest

Spectral splatter

A tone that lasts 10 msec or less. Side band energy. Sound wave is cut off. hear part of a sound but more of a distortion Don't get the cycle in completely

Sensitivity

Absolute Threshold. Minimal magnitude of stimulus. How low can you hear a sound.

Frequency and Pitch

Although the primary determiner of pitch is frequency, the intensity of the sound may influence the pitch that one perceives. There, a tendency for low frequency tones to sound lower pitch as intensity is increased and high frequency tones to sound higher in pitch as intensity is increased.

Forward Masking

An ongoing sound is turned off, leaves a momentary trace or after-effect. This after-effect will raise the threshold of a stimulus which follows the sound if the stimulus is presented within about 50 ms of the "off" time of the sound. This is called forward masking. If a tone A is presented and another tone B is presented within 50 msec of the offset, then masking of B will occur due to residual effects of tone A. Why? Due to the persistence of the maskers representation in the auditory neural pathway. -Neural interference-neurons are still firing for the first tone

Peripheral Masking

Anything that occupies the cochlea and blocks sound out . loud sound vs. soft sound There has been considerable research on peripheral masking done is an effort to define cochlear physiology. The PLACE THEORY of hearing assumes a specific place of stimulation on the basilar membrane for a particular frequency. If so, to prevent that frequency from being heard, one would only need to occupy that space on the basilar membrane. However, occupying any other space on the membrane should not affect the hearing for that frequency. This line of thinking has produced

Difference b/w a beat and warble?

Beat-intensity modulated- need 2 tones Warble-Freq. modulated-need 1 tone-little above & above

What do you use when looking for intensity differences?

Beats. 2 tones

What range is human hearing MOST sensitive?

Between 2000 and 5000 Hz

Central Masking

Central auditory nervous system. Introducing a noise into one ear, raises the threshold of the other ear. mysterious-put noise on one side of ear but gets to other ear-something happens -interferes "Central masking is not the result of stimuli interacting at the cochlea but is the result of some inhibitory effect in the central nervous system. Introducing a noise into one ear will raise the threshold of the opposite ear even when the noise is not intense enough to acoustically cross the head in the opposite ear. The physiology of central masking is uunknown.. It does not exceed about 10 dB."

DL ________ as intensity_______

DL Decreases as intensity increase (improves)

For frequency, the difference limens are smaller (better) for high or low frequencies?

DL better at intensity increase and better for higher frequencies and worse for low frequencies

Dl larger and smaller when?

DL larger at low freq. and smaller at high freq

Which physical parameter(s) of sound can affect binaural fusion?

Either intensity, time, or frequency (phase)

Bekesy's adaptive procedure

Example of Method of Adjustment Adaption of the clinic procedures to make them move clinically applicable The levels of stimuli are adjusted by experimenter but the direction of level change is controlled by the subject via a push button switch. Caused motor to DECREASE sound level and when it is depressed and to INCREASE the level when it is up Threshold is tracked through using the subject, and its value it is the AVG. OF THE MIDPOINTS OF THE EXCURSIONS on the recording (once stabilized) MIDPOINT=THRESHOLD Press till you hear, don't press when you don't hear Combines both method of limits and adjustment.

Stevens (1935) - asked subjects to adjust the intensity of a tone until it had the same pitch as a standard tone of slightly different frequency.

Found that: increasing the intensity of the tone increased its pitch for frequencies 3000 Hz and above; increasing the intensity of the tone lowered its pitch for frequencies 1000 Hz and below. The pitch stayed essentially constant between 1000 and 3000 Hz.

Fletcher and Munson (1933) Equal Loudness Curve

Found: -At low loudness levels curves are similar in shape to the minimum audible field (MAF) -Thus more intensity is needed to achieve equal loudness for lower frequencies than for higher ones.

What are Warble Tones? What do they help measure?

Freq. modulated (only need 1 tone a little above and below) Used in frequency-varies the frequency (how much can you tell diff. between the two) Testing with hearing aids-the smaller the better (discrete changes)

For durations which are ____ the ear treats as though they are infinitely long increases above the level do not change the ________

Larger than 300 msec, threshold level

Stevens (1936) Subjective Loudness Scaling-

Loudness scales show how the loudness perception is related to the intensity of the sound stimulus. Since we are interested not only in the loudness of a particular sound, but also in how much louder one sound is than another Sone- unit of loudness of a 1000 Hz tone presented at 40 dBSPL. This is 1 Sone

What type of frequency wraps around head? Gets blocked?

Low Frequencies wrap around and high Frequencies get blocked

Silvian and White 1933

MAF freq. curves fell below MAP 6dB Difference

masking

Masking occurs when one sound causes another sound to be less audible by a.) co-existing with it b.) appearing very near it in time umay result from interactions at the cochlea (peripheral masking) or from interactions with central auditory nervous system (central masking)

Does minimal Audible field or pressure give better results? By how many dB?

Minimal Audible Field. There is a 6 dB difference.

What was found in the quantal method?>

Normal ears couldn't detect. Found you NEEDED SEVER dB to HEAR AT LOWER SENSATION LEVELS However, the SOUND COULD BE HEARD AT 1 dB at HIGHER INTENSITY (sensation) levels and the HIGHER THE FREQ. the BETTER the DETECTABILITY dL allows to hear small changes

Reisz on intensity discrimination

Reisz (1928) reported the DIFFERENTIAL SENSITIVITY for intensity over a WIDE RANGE of FREQ (35HZ-10kHz) and sensation levels (0-100dB) Had a problem-switching on and off (it made an audible clicking sound) Whenever you change a stimulus abruptly the transducer oscillates and causes sound- switching transient or distortion product These noises cause energy to spread to other freq. that the one being tested Reisz used beat tomes to detect the Dl OR jnd

Monophonic

Same signal each ear

Shower and Biddolph 1931

Saw problems with sensitivity transientss from earlier experiments Solved this by using the FREQ.-MODULATED (FM) TONES-slightly above and below frequency Subjects were to detect the presence of a modulated tone as opposed to a steady tone The Dl was taken as the smallest difference in freq. that produced a perceptible modulation of the origonal tone.

SoNn

Signal binaural, in-phase, noise binaural, out-of-phase

SnNo

Signal binaural, out-of-phase, noise binaural, in-phase

Quantal Method

Signal on going and increment added. Sound jumps up. Short increment sensitivity index (sisi) by JERGER, SHEDD, HARFORD (1959) Set w/ 20dBSL (above threshold) of ongoing stimulus or (I). Then he added an additional change, an increase or JUMP in intensity of 1 dB

Best result of release from masking?

SnNo

Binaural Fusion

Sounds usually similar but not identical when they reach the 2 ears Binaural fusion- one sound heard from 2 separate ears Where sounds come together--fused in the center of head Ex: music under earphones, listener hears as unified sound, not as something in the right ear and left ear- music is equally loud in the 2 ears, fused image occurs in center of head

Method of Adjustment

Subject controls the stimulus. Level of Stimulus is varied continuously instead of discrete steps Threshold is taken as the avg. of the audible and the just inaudible levels

Method of Constant Stimuli

Take a multiple stimuli and give them in random order/ Various stimuli levels in a random order. Non-sequential procedure. finds point at 50% threshold Disadvantage--inefficient prolonged test time

Minimal Audible Field (MAF)

Testing a subject's thresholds through a speaker (sound field).

Minimal Audible Pressure (MAP)

Testing someone's thresholds through earphones. Monitor the pressure in the ear canal.

Method of Limits

The STIMULUS is under the EXPERIMENTERS's CONTROL and the SUBJECT SIMPLY RESPONDS after each presentation. EX. Suppose we are interested in the absolute sensitivity (threshold) for a particular sound 1. Sound is presented at a level expected to be well above THRESHOLD (level we can hear 50% OF THE TIME) 2. Since it is CLEARLY AUDIBLE- the sound responds by stating the heard sound 3. The level of the SOUND IS THEN DECREASED BY A DISCRETE AMOUNT (2 OR 5db) and presented again (till sound is audible) Change intensity. Does multiple ascending (inaudible to audible) and descending runs (audible to inaudible) to take away anticipation and Bias. Step size = 5dB Crossover between the "hearing and non hearing" lies somewhere between lowest audible level and highest inaudible-"threshold" THRESHOLD for each series may be taken as the HALF WAY POINT-b/w them Too large a step size reduces accuracy (b/c the actual threshold may lie anywhere b/w 2 discrete stimulus levels A smaller step size permits a more precise estimate but may be more tedious-may have a few wasted presentations

What can cause a sound to lateralize from one ear to the other?

The actual difference in the time of arrival of a sound to the two ears. Sound will reach one ear before it reaches the other ear except in those cases where the two ears are the same distance from the sound source.

Binaural summation

The energy comes together- can hear better with two ears than with one A summation of the acoustic energy reaching the 2 ears reflected in binaural thresholds for pure tones and complex stimuli- about 3 dB lower (better hearing) than monoaural also evident in loudness perception monoaural tone must be 3 to 6 dB more intense to be judged equally loud to a binaural tone of the same frequency -3dB sensation difference at low sensation levels increasing to about 6 dB at high

absolute sensitivity

The point of detection of a sound Tells us about auditory system and how it works Decreases when the duration of a stimulus becomes much shorter than a second; and the nature of this phenomena reveals an intensity property of the auditory system It changes becomes worse as we begin to have less and less time of the tone Measured in means, median, mode

How is the adjustment method different from the method of limits?

The stimulus is CONTROLLED BY THE SUBJECT instead of the EXPERIMENTER The level of the stimulus is VARIED CONTINUOUSLY rather than in DISCRETE STEPS

Resolving power

When you can distinguish sounds EX. Is there a difference between A & B, how close can that diff. be to discriminate/tell the difference

Psychoacoustics

an effort to determine what an organ can or is capable of doing-the resolving power of the sensory mechanism Perception of sound and how corresponds with the freq. measures of intensity tries to determine what you hearing system is CAPABLE OF DOING-what is the best way/HOW CAN WE PICK OUT its CAPABILITIES

The subject's threshold is obtained by

averaging the threshold levels across runs.

Modern Psychophysics

based on STATISTICS and MATHEMATICAL MODELS includes variable such as the persons willingness to GUESS or MOTIVATION -takes large # -many uncontrollable variable -variables dissipate through stats.

halfway point

crossover between "hearing" and "not hearing" lies somewhere between the lowest audible level and the highest inaudible one, the "threshold" for each series

As intensity increases what happens to the difference limen?

decreases-better as intensity increases and better for higher frequencies and worse for low freq

Response Proclivity

describes how someone behaves. If they are having a bad day...

Sterophonic

different signal each ear- not always simultaneous

Dichotic

different stimulus present simultaneously to each ear 2 signals, different pitch, same time

Cons to method of limits

forms of response bias in method of limits Subject may anticipate an answer and the step size Since the series either ascends or descends and is terminated by a change in response, the subject may anticipate the level at which his response should change from: "no" to "yes" for an ascending run or "yes" to "no" for a descending run. Anticipation thus results in a lower or better ascending threshold and a higher or poorer descending threshold since he anticipates not hearing. Bias may be minimized by using an equal number of ascending and descending test run Step size- (dB increment) Too large a step size reduces accuracy because the actual threshold may lie anywhere between 2 discrete stimulus levels (ex: 10 dB vs. 2 dB) A smaller step size permits a more precise estimate but also may be more tedious and may have a few "wasted" presentations due to test levels well above or below the threshold.

Place theory

hearing assumes a specific place on basilar membrane for a specific frequency.

Auditory processing

hearing something but can't understand-but when someone says what it is you can hear it

Minimal Audible levels/curves- Where is the human ear most sensitive?

how much sound intensity is necessary to just detect stimuli- our hearing is sensitive to some frequencies than others most sensitive between about 2000 and 5000Hz

Localization

in sound field find space in area of sound source Ability to depends on utilization of a complex interaction of TEMPORAL TIME and INTENSITY CUES

What can affect binaural fusion?

intensity, timing , phase

Intensity

is the physical parameter of the stimulus

Frequency discrimination

looking at the quality differences while keeping the magnitude the same

Response Proclivity

manner in which they respond. Also includes biases and criteria that affects his response. the BIAS from the testing -what happens before testing-bad day

What is a Phon? What does it measure

measure of loudness. Equal to dBSPL @ 1000 Hz Equal loudness contour-where do you hear in comparison to all the other frequencies to 1000 hz Comparing loudness for each on of those

Mels and What does it measure?

measure pitch. 1000 if freq= 1000 Hz and 55 dBSPL

Up-Down (Staircase) adaptive procedure

most used clinically Increase stimulus level when subject does not respond to a presentation, and decreasing the intensity when there is a response. Difference from limits method: Testing does not stop. A "Run" - group of stimulus presentations b/w two response reversals ascending (goes until positive response) and descending (goes until negative response) converse-50% level

Time of arrival at 2 ears is NOT dependent on nature of sound because...

neither frequency nor intensity affects the speed of sound. Related to PHASE DIFFERENCES at the 2 ears. Most sounds not originating in the median plane arrive out of Phase to some degree. The degree to which depends on the distance between the 2 ears and the wavelength of the sound. Only sounds of low frequency, where ½ the distance of wavelengths are longer than interaural distance provide unambiguous phase cues.

Backward Masking

one tone comes after the other tone within 100 ms timing difference-messing with the neurons If a second tone is presented within a certain time (100msec) FOLLOWING the 1st tone, it can have a masking effect on the 1st tone. WHY? Occurs because the masking is present before the auditory nervous system can consciously process it.--Overloading the nuerons-intensity drops from the first tone

Classic Psychophysics

psychological variables are for the most part uncontrolled usually TAKE A FEW SUBJECTS and TRAIN rather than controlling for STATISTICALLY -many paid trained scientists and grad students -trained to hear sound -works with a good group

Diotic

same stimulus presented to ear identically- at same time

Stenger Effect

signal perceived only in the louder ear. Unaware of the sound in the softer ear. use second tone after first tone, effects the first tone (decreases the first tone) What happens in binaural integration (listening to sound-locating sound with eyes closed-is it located in the head) Shift in both sides-Present sound equally on both sides—can adjust volume on one side vs. the other Sound is presented sooner-than one sound is more heard than the other (can't fake it) Impossible to fake in this hearing test-

descending run

stimulus level begins above threshold and is lowered until the subject can no longer hear the tone Audible to inaudible

ascending run

stimulus level begins below threshold and is raised until the subject can barely hear the tone Inaudible to audible

Monotic

stimulus presented to only one ear

temporal integration or summation

the ear operates as an ENERGY DETECTOR that samples the amount of energy present within a CERTAIN TIME FRAME. changes has to do with timing How we pick up sounds in a certain time frame

Sounds will lateralize toward _____________________

the noise that is louder/closer

Pitch

the perceived frequency of a sound/frequency as the psychological correlate of frequency measured in mels Defined as a pitch that is 1/1000 of the pitch of a 1000Hz tone at 55 dB SPL Thus, 1000 mels is the pitch of a 1000 Hz tone at 55 dBSPL 20,000 Hz is focused down to a pitch surge of only about 3500 mels *These frequencies doe not produce a perception of "tonality."

Difference Limen or just noticeable difference?

the smallest perceivable difference between two sounds.

Above 20,000 Hz we are _______________

unaware of sound

Lateralization

under headphones perceived sound in head- (stenger effect) Intensity. time of arrival and frequency/phase effect how it sounds intensity-1dB detection b/w midline, sound shifting to one ear more than other, 10 dB over-can't perceive time of arrival- sound moves toward "leading" ear, delayed time of arrival , as small as 10microsec can be detected as a shift, if both ears hear the same-it will sound equal in head Phase-wavelength can effect hearing

Sone and what it measures

unit of loudness of a 1000 Hz tone presented at 40 dBSPL. This is 1 Sone Since SPL in dB and loudness level in phons are equivalent at 1000 Hz- we may also define 1 sone as the loudness corresponding to a loudness level of 40 phons. ****Found overall that a 9 dB increase in SPL usually causes a doubling of loudness. We may therefore express loudness in sones as a function of loudness levels in phons as well as a function of stimulus intensity. Measure of loudness. equal to 40 Phons. 3x louder The more intense the sound the better-fires more rapidly in the cochlea/same with high frequ. 2x as loud-only increases by 9db assign value to 1 sone use as reference then 2 sones will be at an intensity that sounds 2 times as loud as the reference ½ sone ½ as loud

What do you use when looking for frequency differences?

warble. Frequency modulated tones. 1 tone

Sensory Capability

what the subject actually hears