Pitch Flashcards
Where does spectral analysis occur?
In the cochlea (inner ear)
What article validates this spectral theory?
Oxenham et al., 2004
What is tonotopy?
Depending on the spectral components of the sound, the basilar membrane resonates at different locations - each location actives different nerve cells
Links to concept of auditory filters
How does the basilar membrane work?
Fluid in the cochlea
Base has a thick structure - so vibrates at high frequencies
Apex has thin structure - so vibrates at low frequencies
What are stereocilia?
Cells that sit on the basilar membrane to convert physical movement into electrical signals to nerve cells
What is the template matching process
Corresponds to a set of equally spaced harmonics, each corresponding to integer multiples of a common fundamental frequency
When the template pattern is matched brain merges one auditory precept, the lowest harmonic = fundamental frequency
What are the retained frequencies?
Regions characteristic = width of filter is called the critical band
What is volley theory?
When each individual neuron fires in quick succession in order to make up the wave
What is phase locking?
The entrainment of nerve cells to the periodic motion of a wave
What species is phase locking identified in?
In mammals - after 4-5kHz the ‘just noticeable difference becomes larger as the nerve cells can’t fire quickly enough to keep up with the frequency’s periodicity
What is autocorrelation analysis?
Looks for the time lag at which the signal correlates highly with itself = time lags with high correlation are likely the fundamental frequency
When does phase locking break down?
Up to around 2-4kHz (Palmer & Russel, 1986) - this is when spectral mechanism takes over - 4kHz is the highest-pitched instrument therefore musical pitch relies on temporal mechanisms
Broad comparison between temporal and spectral theories
Temporal is more specific than spectral
Temporal links to frequency, spectral links to the location
Temporal uses autocorrelation analysis, spectral uses Fourier analysis
A temporal example is it is found in mammals, the spectral example is the Oxenham et. al, (2004) paper
