Exam 2 Audition Methods Used in the Study of the Senses What are the 5 main methods we discussed for studying sensation and perception o 1 thresholds o 2 scaling measuring private experience is your qualitative experience of red the same as mine o 3 Signal detection theory measuring difficult decisions the body of research that studies the detection of signal in noise why Because we don t live in a lab because variability in threshold has a lot to do with the subject noise in the nervous system noise in the environment subject s expectations and biases o 4 Sensory neuroscience o 5 Neuroimaging associating activity in various brain regions with perceptions or experiences What is psychophysics What are some examples of psychophysical methods o Psychophysics the science of defining quantitative relationships between physical and psychological events o Why because there is a difference between sensation and perception and because there is a difference between changes in physical stimuli and our perception of them What is the just noticeable difference o The minimum intensity needed to perceive a difference between 2 stimuli o Pitch brightness electric shock saltiness vibration etc What is the 2 point threshold o The closest distance 2 points of stimulation touch can be and still be perceived as 2 distinct points What are 3 methods of measuring the absolute threshold o Absolute threshold minimum intensity of a stimulus that can be detected 50 of the time o Method of constant stimuli o Method of limits o Method of adjustment What is cross modality matching o So you can compare apples to oranges o Subject is asked to match intensities of sensations that come from different sensory modalities ex adjust brightness of light to match loudness of a tone similar results across subjects What is magnitude estimation What does Steven s Power Law tell us about our perception of changes in stimulus intensity o Magnitude estimation subject assigns values according to perceived magnitudes of the stimulus ex rate pain on scale of 1 10 o Steven s Power Law even though our response with regard to stimulus intensity changes for each sense the same law applies for each sense What is signal detection theory and why is it more relevant to the real world than absolute thresholds noise in the real world o Studies detection of signal in noise because we don t live in a lab there is What is sensory neuroscience What does evolution have to do with this o How our perception of the world depends on the activity of our sensory nerves at least as much as it depends on the world itself o Doctrine of specific nerve energies the same cause can affect all sensory organs since they are all sensitive to it they all conduct it and yet every sensory nerve system reacts to it differently one nerve set of brain regions perceives it as light another hears its sound another one smells it another tastes the electricity and another one feels it as pain and shock What are 2 neuroimaging techniques o fMRI functional magnetic resonance imaging activated neurons induce increased blood flow o PET scan positron emission topography identify active areas of brain by measuring decay of safe radioactive isotopes Sound correlates What are the 2 main components of sound and what are their psychological o Amplitude decibels corresponds to intensity loudness is the perception of intensity but as intensity doubles loudness does not o Frequency Hertz 1 Hz 1 cycle second corresponds to pitch Why do we use a log scale for decibels o Log scale describing sound pressure level SPL o 0 dB is a reference point corresponding to the very quietest thing that a healthy ear could possibly hear o log scales compress a large range into a smaller range if a whisper has a level of 1 a jet engine has a level of 10 000 000 o what seems like a small change in decibels can actually reflect a huge change in sound pressure amplitude What is an audiogram What is a spectrogram What is a sonogram o Audiograms generated using pure tones as test stimuli o Spectrogram a spectrum displays the amplitude for each frequency present in a sound wave each signal is shown as a waveform and as a spectrum The lowest frequency is the fundamental frequency the other frequencies present in the sound are called harmonics o Sonogram if we plot a spectrum over time What is the difference between a pure tone and a complex tone o Complex tones are real sounds multiple tones combined What are fourier analysis fourier synthesis o Fourier analysis complex sounds can be broken down into their pure tone components Harmonic spectra spectrum of a complex sound in which energy is at integer multiples of the fundamental frequency caused by simple vibrating sources Harmonic a tone that is a component of a complex sound whole number multiple of the fundamental frequency Harmonics are always evenly spaced multiples of the fundamental frequency so the higher fundamental frequency pitch the further apart the harmonics will be o Fourier synthesis complex sound can be created by adding pure tone components What is the fundamental frequency What are harmonics What is timbre and what does timbre have to do w harmonics o Fundamental frequency lowest frequency in a spectrum o Harmonic sounds with the same fundamental frequency so same pitch sound different because the amplitudes of individual frequency components are different o Timbre perceptual quality of a complex sound altered by combinations of harmonics sounds sound different because they have their own unique timbre sound different because harmonics have different amplitudes Why do different instruments playing the same note sound different o Sound different because harmonics have different amplitudes o Size and shape of space through which sound passes increases and decreases energy at different frequencies In general what does the study of psychoacoustics tell us about the relationship between amplitude and loudness What about the relationship between frequency and pitch o Psychoacoustics the study of the psychological correlates of the physical dimensions of acoustics o Energy perception a positive correlation exists it is just not 1 1 o intensity loudness perception does not increase as fast as perception also longer sounds are heard as louder why Temporal integration summation of energy over a brief but noticeable period of time o Frequency pitch We are very sensitive to changes in frequency we can discriminate between 999Hz and 1000Hz Not as
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