Mcq Flashcards
(52 cards)
What are the perceptual and physical characteristics of hearing?
Perpetual-Loudness Physical- intensity SI
Perpetual- Pitch Physical- Frequency SI (hertz)
What are the two dimensions of pitch?
Height- going from low to high
Chroma- which describes the similarity of the note
What is Timbre?
A perceptual characteristic of sound
Can be described as dull, bright, warm
Timbre sometimes referred to as quality of music
What are such perceptions that we can quantify and ask how much called? E.g. One light twice as bright
Prosthetic continuum
Perceptions when you can not put a value on stimulus are called?
E.g. It doesn’t make sense to ask if a red hue is more or less than green hue
Metathetic continum
The difference that can be detected in 50% of trials is referred to as?
JND just noticeable difference
or Difference threshold
What is the absolute threshold?
Related to single stimulus, the level where the stimulus can just be detected as being present
E.g. From nothing to first hearing sound
Related to detection
Lowest level of an auditory stimulus that is audible
( usually sinusoidal simulation-pure tones)
What is the difference threshold?
JND smallest difference between stimuli that can be discriminated
Smallest change in stimulus which a person can detect 50% of the time.
What is the point of subjective equality PSE
Point
Subjective
Equality
Equal (perceived)
Point of comparison where stimulus is judged or perceived to be equal to standard stimulus
What is POE
Point of
Absolute
Equality
Equal (objective)
POE
The point where a comparison stimulus can actually be measured to be equal
Detection of an acoustic signal is related to?
Sensitivity
The
Detection threshold +
Difference threshold (JND)
Are inversely related to?
The absolute sensitivity
Therefore the greater the absolute sensitivity the lower the detection threshold
E.g. The better detecting something there
What is detection
Determine if present or not
Can be considered case of discrimination
Can you distinguish (discriminate) the stimulus from no stimulus
What is discrimination?
Ability to DETECT DIFFERECE between one signal and another i.e. Tell the difference between frequencies and intensities. in sound
The difference threshold is inversely related to the DIFFERENTIAL SENSITIVITY
The greater the differential sensitivity the lower the difference threshold
(Better at detecting difference between or discriminate between stimuli)
Methods of measuring sensitivity to a stimulus
Method of adjustment?
Simplest method of finding a stimulus threshold is to ask a participant to adjust the sound level with a dial until they can just detect the presence of the stimulus
Can be used to measure RELATIVE THRESHOLD
METHOD OF ADJUSTMENT
Final threshold value depends on if threshold is approached from above or below(start well belo/above)
Methods of measuring sensitivity to a stimulus
Method of limits?
Tester controls intensity
At each intensity participant presses a button if they can perceive the stimulus
Advantages quick, can be used with AFC or 2AFI. Duration under control of tester
Negatives- poor trials
Methods of measuring sensitivity to a stimulus
Method of constant stimuli
Stimulus presentation doesn’t depend on participant response
Randomised
Usually automated
Think hearing tests I did in military
Measures of absolute threshold
Minimum auditory field (MAF)
MINIMUM AUDITORY FIELD (MAF)
Sounds played in FREEFIELD
Presented over loudspeaker in a anechoic chamber
Listener usually 1m away
Calibration of SPL doesn’t account for body
Measures of absolute threshold
Minimum auditory pressure
MINIMUM AUDITORY PRESSURE (MAP)
Sounds played over HEADPHONES and minimum audible pressure is measured at the tympanic membrane TM
Measured SPL
Usually monaural
Headphones don’t account for head diffraction, ear canal resonance etc
Position of probe microphone affects measurements at high frequencies (standard waves)
Measures of absolute threshold
Hearing level
HEARING LEVEL (HL) Measure based on estimate of minimum audible pressure at TYMPANIC MEMBRANE (TM)
What range of frequencies does the unmanned ear “hear”
20Hz to 20kHz
Most sensitive over mid frequencies 1to4kHz
At 1kHz the normal threshold is about 0dB SPL or 20uPa.
Why do we measure in RETSPL?
Not MAP or MAF
They are difficult and time consuming. So we use: RETSPL
Reference
Equivalent
Sound
Pressure
Level
For the particular headphones and measure the threshold relative to that for young ontologically normal listeners. That is a hearing level (dB HL)
What is acoustic intensity measured in?
W/m2
Where Wis the power in watts
Power=energy/time
What is Criterion?
Influencing factors
Bias
