Psychoacustics

Seperation and reorganization of multiple sound sources into meaningfull units

important: node at ~3-4kHz

range from 20 - 20kHz

depending on age expassially at high frequencies

Native: primitive stream segregation

Learned: scheme based segregation

ability to detect diffeneces in stimuli over time

e.g Gap detection

ability to cumulate information over time

e.g. absolute thershold reflects

the perception of rapid sequences of sound as if they come from one continous sound source

the perception of sequences of sound as originationg from multiple sources

sounds that are similar in frquency are grouped togehter into a single stream

components that start and end at the same time are grouped together

grouping of tones that based on their perceived spatial location

thershold of speech inteligibility depending on localy sperating signal and noise

the minimum of level of speech (in dB) required for the listener to understand 50% of the words

an objective measurement to predict the inteligibility of speech between 0 and 1

quotient of the modulation depths at the output and input of the channel

determind in frequency bands

Measure between 0 and 1

quantificaton of prportion of speech information that is audible and usable for the listener

indicaters how much noise can interfere with speech so it remains understandable

Measure between 0 and 1

quantificaton of prportion of speech information that is audible and usable for the listener

Yes same as AI but the new one

the principle that makes it easier to detect a soudn between noise if it is differnet in time or phase

BMLD with speech for a certain degree of inteligibility

Head related Transferfunction

200 - 500Hz : torso

500 - 1500Hz: head

1500 - 3000 Hz : outer ear / pinna

f> 3000Hz : ear canal (middle / inner ear)

a difference in time from the signal reaching the left or the right ear

used for localization

important at low freq (f < 1500Hz)

differnece in Level between ears

important for high freq (f > 1500 Hz)

frontal plane -> front and back

horizontal plane -> top and bottom

median plane -> left and right

unit: sone

subjective percieved loudness

reffernce a tone at 1kHz and 40dB -> 1 sone

phon (1 sone = 40 phone)

reffernece a tone at 1kHz at 40dB -> 1 phon

acum

balance between high and low components

reffernece at a tone 1kHz and 60dB -> 1 acum

asper

fast amplitude change or frequence modulation

reffernce at 1 kHz and 60dB 100% with 70Hz modulation

vacil

slow amplitude modulation

refference 1 kHz at 60dB 100% modulation with 4Hz

tu tonality unit

refference at 1kHz at 60dB

realtion between level and yes responses

masking thershold for a test tone by narrow band masker with a center freq of 1kHz

pre: a way louder masker can mask a signal up to 20ms after the signal

simultaneous : both at same time

post: after a masker is played the haircells need to recover up to 150 ms to receive anything after it (the signal after masker (0-150ms is masked)

weighted level (a or weighted)

one cruve stand for a tone that seams equal loud depending on freq and level

A weighted: 40 phone -> 1 sone -> 40dB at 1kHz

at 1kHz phone = SPL [dB] and

independent variables: are independent and can be changed to observe changes in the results (DV´s)

depending variables: describe the outxome and are depending on the IV´s

To proof a relation of IV and DV:

IV have do be before DV in time

they have to correlate

every other causes must be eliminated

H0: we want to denie it always. never accept it

H1: it does exists an difference that we measured. if we accept H1 we can denie H0

Type 1 (alpha) : wrong positive -> we denie H0 even though it might be true

usually max 5%

Type 2 (beta): we dont notice the difference that is there and denie H1 even though it is true

usually max 20%

statistic power 1-beta

describes the probability to detect a effect that existst -> 80% is wanted

Halo: a single stimuli overpowers all others and influences rating

Primary-Recency: the order of stimuli influences the rating

Hawthorne: learning effect

investigator artefact: admin can inlfunce with noverbal communiaction

Within - subject: a person tests all stimuli

• positiv: better comparison, less people needed

• negative: learning effect/ carryover effect, effect of tierness -> counterbalancing needed

Between - subject: Group A test stimuli 1, Group B stimuli 2

• postive: no learn effects

• Negative: more people needed, better radnomization needed

latin square

balanced latin square

controlled by test person

value at adjustement is recorded

pro: fast, intuitive for people

con: stronlgy subjective, low accuracy

(X50% is wanted, strongly subjective due to subject controlled adjaustement)

different stimuli level at random order: constant stimuli level chages within signal

yes or no answers, forced response

pro: high accuracy, unbaised estimate

con: very time consuming, many trials needed

aims at X50% point, alternitivly 70 or 75%

level is adjusted based on subjects response

correct -> level decreases

incorrect -> increases

pro: efficient

con: depends on ruel choice

X50% is wanted: the stimuli is hearable in 50% cases

Up/Down wtih asymetric streps

1up/2 down -> target 70,7%

pro: flexible, precice threshold definiton

con: more complex, carefull parameter choice