Hearing & Language Flashcards
What are the most interesting problems in auditory perception?
4 points
- perceptual basis of harmony
- recognition of voices
- separating signal sources
- influence of experience and knowledge
What is misophonia?
a strong negative reaction from hearing specific human sounds
The nature of sound
A sound source is emitting (repeated) circular pressure waves (shells of air compression) i.e. a tuning fork → waves are similar to dropping a pebble into a still pond
properties of sound waves: what is a pure tone represented by?
A pure tone is represented by a sinewave (air pressure as function of space/time)
What is frequency the measure of?
pitch
how to measure frequency?
1/period, measured in Hz = cycles per second
What is amplitude the measure of?
loudness
what do notes of a musical score?
+ 2 points
the keys on the piano:
- frequency generated
- pitch of a musical tone
how are keys arranged on a piano/keyboard?
in the order of rising frequency of the musical tone generated
what are harmonic intervals?
The distance between two pitches that are sounded together at the same time
what are harmonic intervals determined by?
the characteristic frequency ratios
what is superposition of waves?
when two or more waves travel through the same medium at the same time
what happens to the waveform when you superimpose pure tones ?
more complex sounds: chords, consonance, dissonance, vowels
what are musical tones combinations of?
pure tones: fundamental (determines pitch) + harmonic frequencies (determine timbre)
what is white noise?
the superposition of many tones with random amplitude and frequency
what is a transducer?
a device that changes energy from one form to another
is the human ear a transducer?
yes - it changes sound waves into neural signals
what is the outer ear?
a directional microphone
what is the order of hearing?
outer ear, middle ear, inner ear
what is the function of the outer ear?
directional microphone
what is the function of the middle ear?
impedance matching, overload protection
what is the function of the inner ear?
frequency analysis, neural encoding
what is extreme sensitivity?
absolute threshold at sound levels that generate eardrum vibrations - 0.1 nm (H20)
what is frequency masking?
when the perception of a sound is affected and covered by another distracting the ear
what is a systematic variation?
anomaly or inaccuracy in observations which are the result of factors which are not under statistical control
how is perceived loudness measured?
perceived loudness is measured by comparing successively presented tones (or different frequency)
the intensity of comparison tone is adjusted until…
The same ‘subjective’ loudness is matched to the reference tone
comparing many frequencies ->
curves of an equal loudness
what is physical intensity recorded as?
physical intensity (SPL = sound pressure level) is recorded as ‘perceived loudness’
what is an audiogram?
a graph that shows the softest sounds a person can hear at different frequencies or pitches
what happens if you combine loudness and frequency detection in full audiogram?
loudness comparison as function of frequency (20Hz – 20 KHz)
what is an equal loudness contour?
a measure of sound pressure over a spectrum of frequencies, perceived as being equally loud to the hearer when expressed as a pure, constant tone
what are equal loudness contours determined by?
by matching the perceived intensity of tone pairs at various base intensities
how many decibels is danger level?
90 dB & 100 dB
how many decibels that are a risk to our hearing?
120 dB
how many decibels is pain level?
140 dB
what kind of sounds are mainly in the lower frequency region?
vowel sounds are mainly im the lower frequency region
what is presbycusis?
presbycusis is a selective high-frequency hearing loss with age (ongoing)
what can noise exposure lead to?
noise exposure can lead to temporary threshold shifts (auditory fatigue) and permanent (partial) deafness
What is tinnitus?
tinnitus is a continuous humming or ringing which leads to suppression
what is a melody?
a sequence of tones in time, such as simple a chord
what do scientists use to display and analyse real sounds?
spectrograms or sonograms: frequency as function of time
what does the chord show?
the schematic spectrogram as sequence of different fundamental & harmonic frequency clusters
what is a spectrogram?
A spectrogram visually displays the strength of a signal over time at a waveform’s various frequencies
what is a sonogram?
imaging method that uses sound waves to produce images of structures within your body
what does each spoken word generate?
a complex pattern of frequency and intensity (spectrum), which is modulated as function of time
what are complex patterns of frequency recorded as?
spectrogram (time, frequency, intensity) and waveform envelope (microphone)
extracting meaning from sound flow diagram
Where is Broca’s area?
in the frontal lobe
what is the Broca’s areas function?
speech production (patient ‘Tan’)
where is Wernicke’s area?
in the temporal lobe
what is the Wernicke’s areas function?
fluent aphasia (phrases without meaning)
what kind of sensor is the ear?
1D
what is sound localisation?
the ability to tell the direction from which a sound is originating
what is the pinnae?
the external part of an ear
why is the pinnae important?
its crucial for sensation of space (earphones) and to locate elevation
what is inter-aural
time differences in arrival time of a sound between two ears
why is inter-aural important?
processes to find azimuth (left-right) of sound source:
what is an intensity difference?
an acoustic ‘shadow’ of the head
what are temporal or phase differences?
inter-aural delays of 10 - 650 µsec
what is the cocktail party effect?
refers to the ability of people to focus on a single talker or conversation in a noisy environment
how can the cocktail party effect be achieved?
by masking: the detection of a tone is impaired if another tone or noise is presented at the same time. This depends on proximity in space and similarity in frequency composition
what is binaural unmasking?
spatial distance and difference in frequency support
separation < difference between ears
what are high-level effects
attention, familiarity of voice, language & sensory fusion
