Hearing Science 3

masking

when the presence of a second sound interferes with the perception of the target sound— prevents ear from hearing sound in the other ear

how a psychophysical tuning curve is measured

using a masking paradigm to determine frequency selectivity of the auditory system. finds the minimum level of auditory masker to make a fixed low level target sound

bandwidth narrows

tones are easier to detect

according to the duplex theory of localization, why is it more difficult to accurately localize sound sources with frequencies in the region of 1500 Hz than in lower or higher frequency regions

low freq under 1500 Hz, ITD, tiny difference in arrival at ears

high freq above 1500 z, ILD, difference in intensities between ears

1500 is hard because neither cues work well at this level

how does the pinna help localization cues

works as a filter affecting high frequency sounds, creates spectral cues as sound is diffracted and reflected, helps differentiate elevation

sound localization

3 acoustic cues (ITD, ILD, filtering), binaural hearing, identify physical location of sound in a 3D shape and often uses head movement

lateralization

when 2 identical sounds are displayed sequentially, they will be perceived as 1 sound of they are close in time.

absolute threshold

the smallest value of a stimulus parameter that a listener can detect. thresholds vary by tone frequency and sound duration

Just noticeable difference and 2 measurements of it

the smallest change in a stimulus parameter that can be perceived by the listener measurements: frequency, intensity, and amplitude modulation

temporal integration

the process by which a sound at a constant level is perceived as being louder when its of longer duration . avg window= 300

temporal modulation transfer function TMTF

measures our sensitivity to modulation depth for different modulation frequencies

weber fraction

JND is proportional to the smaller weight value , states that the weber fraction is often constant for all values of a physical parameter to be discriminated

why are loudness and pitch subjective

they depend on how the listener perceives the sound

resolved harmonic

BM/inner ear separate and process in distinct, individual frequency component

unresolved harmonic

auditory system cant separate at a distinct component leading to multiple harmonics being processed together

temporal theory

the pitch we perceive is determined by the neural firing in AN. pitch is based on the unresolved harmonics and involved higher harmonic numbers

spectral theory of pitch

pitch is from the specific pattern of excitation along the BM. pitch is based on resolved harmonics and involves lower harmonic numbers

sound source segregation

how the auditory system organizes and groups incoming acoustic information into separate perceptual representations corresponding to original sources

Over what frequency range do humans have the best hearing sensitivity (i.e., the lowest audibility thresholds)? 

500-8,000 Hz 

Which physical properties of sound must be considered when measuring audibility thresholds?

Frequency, energy, power, duration 

Audibility thresholds are lower for sounds with longer durations 

true

You measure an audibility threshold for a tone that is 200 msec in duration. If you halve the duration to 100 msec, what will you need to do ensure the sound is still audible? 

increase the signal power

Masking occurs when the presence of a second sound interferes with the perception of a target sound. 

true

In energetic masking, a masker can only interfere with a signal if both sounds happen simultaneously

false

Upward Spread of Masking refers to the phenomenon that masking is stronger for signals with frequencies ______ the masker frequency

above

Which of the following methods can be used to estimate perceptual auditory filter bandwidths?

Critical ratio, Critical band, equivalent rectangular bandwidth 

What are the two main functional benefits of binaural hearing

Sound localization, spatial release from masking 

Sound localization cues from interaural time differences and interaural level differences are greatest when a sound source is located at 90° azimuth. 

true

Lateral superior olive (LSO) 

Neurons receive excitatory input from the ipsilateral ear and indirect inhibitory input from the contralateral ear

Processes interaural level differences 

Medial superior olive (MSO) 

Neurons receive excitatory inputs from each ear 

Processes interaural time differences 

For low frequency sounds originating from sound sources located near midline, how small of a change in azimuth can human listeners perceive? 

1 degree

Compared to when a signal and masker are co-located, there is _______ masking when a signal and masker are separated in space 

less

Based on what we know about binaural masking level differences, for which of the following listening conditions is signal detection easiest? 

dichotic

Which sound is perceived as louder: one measuring 10 phons or one measuring 10 sones? 

10 sones

For a harmonic complex sound, such as the voice, what feature often determines its perceived pitch? 

the fundamental frequency

What term is used to describe the difference between two sounds that are perceived as different but are judged to have the same frequency, the same duration, and the same level? 

timbre

When a complex tone contains several harmonics but no energy at the fundamental frequency, how do listeners typically perceive its pitch? 

They perceive a pitch corresponding to the fundamental frequency, even though it is missing from the stimulus. 

Temporal Theory

More relevant for unresolved harmonics with mid to high harmonic numbers (mid to high frequency components) 

Pitch can be estimated from the periodicity of complex sounds 

Spectral theory

More relevant for resolved harmonics with low harmonic numbers (low frequency components) 

Provides most robust cues for pitch perception 

Pitch can be estimated from harmonic spacing 

Auditory scene analysis (or source segregation) refers to the process of hearing out a sound from a mixture of other sounds by separating the sound mixture into individual sources

true