Pitch Flashcards
What is frequency?
Frequency tells us the repetition rate of a periodic waveform, and is expressed in units of Hz
How do you define pitch?
We define ‘pitch’ as the perceptual correlate of frequency; essentially, we are saying that “pitch is that perceptual quality of sound that derives from the underlying sound wave’s frequency”.
How do we study temporal representation?
We study the waveform, which tells us how pressure changes over time.
How do we study spectral representation?
We decompose the waveform into its constituent sine waves, and we study the frequencies and amplitudes of these sine waves.
What is Fourier transformation?
The process of converting from a temporal to a spectral representation
What is spectral theory?
According to the spectral theory, pitch perception depends fundamentally on a spectral analysis process that occurs within the inner ear, the deepest part of the ear
Where does the spectral Analysis process occurs?
The cochlea
What is tonotopy?
The spatial localisation of frequency components
What is a filter in sound engineering?
an object that selectively retains a subset of the frequencies in a frequency spectrum
What is an auditory filter in context to the basilar membrane?
the way in which particular regions of the basilar membrane behaves somewhat like individual auditory filters. Specifically, a given region of the basilar membrane will only retain frequencies that are close to that region’s characteristic frequency. The width of this filter is termed the ‘critical band’.
What is a template matching process?
where the template corresponds to a set of equally spaced harmonics, each corresponding to integer multiples of a common fundamental frequency, with amplitude decreasing as harmonic number increases. This template could either be innate or learned through experience.
The brain would continually search the spectrum for patterns that matched this template; whenever it identifies such patterns, it ‘merges’ their harmonics into a single auditory percept, corresponding to the complex tone. This percept would have a pitch corresponding to the lowest harmonic in this template, corresponding to the fundamental frequency.
What is the special theory of pitch perception sometimes known as?
‘place theory’ or ‘tonotopic theory’, to emphasise the way in which different spectral components are localised to different places in the ear.
What does pitch perception rely on?
depends on the temporal structure of the nerve impulses that are elicited by this resonance. In particular, the firing patterns of the nerve cells are known to entrain to the periodic motion of the basilar membrane, in what is called phase locking.
What is volley theory?
The idea that multiple nerve cells can work together to entrain to high frequencies. Through this mechanism, the brain can therefore access the main periodicities of the sound wave, represented as temporal firing patterns in the auditory nerve.
What is autocorrection analysis?
The brain looks for time lags at which the signal correlates highly with itself. Time lags achieving high correlations are good candidates for the wave’s fundamental frequency.
