Sensory Systems:

Exam 1February 6 7 8 9 Moodle testing centre

Pitch and Music2PitchPitch is the subjective perception of frequencytime ->

Air PressurePeriod - amount of time for one cycleFrequency - number of cycles per second (1/Period)3Height and ChromaTone Height is the percept of pitch (how high or low)Tone Chroma is the subjective impression of what a tone sounds like400Hz and 500Hz have more similar tone height than 400Hz and 800Hz, but dissimilar chroma400Hz and 800Hz have identical chroma

400 hz

500 Hz

800 Hz4ChromaTones that have the same Chroma are octaves apart

5Chromachroma is best represented as a helixchroma repeats every octavetones with the same chroma are above or below each other on a helix

6ChromaOctaves are equally spaced on the basilar membrane

7Pure Tones are Very Rare in Nature!What are real sounds composed of?8Pure Tones are Very Rare in Nature!What are real sounds composed of?

Virtually all sounds are composed of several (or many) frequencies all going at once9Pure Tones are Very Rare in Nature!What are real sounds composed of?

Virtually all sounds are composed of several (or many) frequencies all going at once

Extra frequencies are called harmonics10What are harmonics?positionupdownimagine a guitar string:

11What are harmonics?positionupdown

imagine a guitar string:12What are harmonics?time ->positionupdownBut more than one frequency can fit between the end points

13What are harmonics?time ->positionupdownf0f1f2In fact many frequencies can be superposed.

14Properties of a Sound WaveA 1 second, 1 Hz sound wave:

15Properties of a Sound WaveA 1 second, 2 Hz sound wave:

16Properties of a Sound WaveA 1 second, 3 Hz sound wave:

17Properties of a Sound WaveSounds superpose (they add together)

18HarmonicsWhen several frequencies are present in the same sound, it is said to have harmonics or overtones

Real sounds, like notes from musical instruments, are complex waves composed of many harmonicsHarmonicsA single note on a piano for example:

HarmonicsIf we zoom in to a small time slice we see a complex wave

HarmonicsIf we zoom in to the very lowest level of detail we see the actual waveform

HarmonicsHarmonics impart a perceptual quality called timbre to a soundTimbre (pronounced like: Tamber)

Pronounciation of timbre24Timbrethe characteristic of a particular set of harmonics is called timbree.g. the set of harmonics generated when a particular key is pressed on a pianotimbre is one reason why we can tell the difference between the same notes played on difference instruments

25TimbreAlthough any musical note is a superposition of harmonics, you still hear it as a single pitch (you hear its tone height)

The pitch that you hear is (usually) the fundamental frequency (except in the artificial case of the missing fundamental)

26HarmonicsIf most sounds are made of several frequencies, then which sound determines the pitch that you hear?27HarmonicsIf most sounds are made of several frequencies, then which sound determines the pitch that you hear?

Typically you hear the lowest frequency component as the pitch of a complex wave28HarmonicsThe lowest frequency is called the fundamental29The Missing FundamentalYour brain so likes to track the fundamental of a set of harmonics that it will perceptually fill it in even when it is absent

missing fundamental30Musical Intervalsin music, notes are played together or in quick successionpairs of notes share a relationship called an interval

31Consonance and DissonanceConsonance is the degree to which two tones played together sound good

Dissonance is the opposite

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