why is pitch important?
- sources of sound (mostly) involve a vibrating object of some sort
–> regular vibration produces sound waves that repeat over tim> w/i a certain range of repetition rates, we perceive the repeating sound wave as beinng associated w/ a pitch - identify the repetition rate or the fundamental freq of a sound to perceive its pitch
–> the variation in the fundamental freq of vowel sounds in speech can be used to convey prosodic info (in english) (eg. question vs statement) and lexical info (in tone langauges)
> musical instruments produce complex tones and the fundamental freqs these tones can be varied to produce diff melodies
> diff in fundamental freq are important in allowing us to seperate out diff sounds that occur at the same time
what kinds of sounds are harmonic complex tones?
musical notes
vowels in speech
what is a harmonic complec tone? (HCT)
consists of a set of pure tones together.
the pure tones have freqs that are multiples ofx the freq of the lowest tone
eg: 200Hz, 400Hz, 600Hz, 800Hz etc…
the tone w/ the lowest freq = the first harmonic (AKA: the fundamental freq)
we can change the pitch of a HCT by varying its fundamental freq and the freq of other harmonics
what is a pure tone?
single freq
the spectrum of a sound is a plot of level against freq
the spectrum shows the freqs that make up a sound
eg. if the freq is 200 cycles per sec (200Hz), the pure tone was created by something that vibrated 200 times each second
melody composed from harmonic complex tones?
we can compose a melody (tune) by varying the fundamental freq (FF) –> and the freqs of other harmonics
what determines the pitch of a harmonic complex tone?
what ohm and helmholtz thought (incorrect) –> pitch of a harmonic complex tone is determined by hearing the freq of the first harmonic (the FF)
BUT: even when the first harmonic is removed, we can still hear the pitches of the notes and still hear the melody. tf, the percept of pitch does NOT require the first harmonic to be audible
AND –> even when the first harmonic is masked by noise, we can still hear the pitches of the notes and still hear the melody. tf, the percept of pitch does NOT require the first harmonic to be audible
what does determine the pitch of a harmonic complex tone? (HCT)
the pitch of a HCT should go up if the greatest common factor of the harmonics goes up, even if the freqs of the available (audible) harmonics go down (pitch is perceived by processes in the auditory system that work out the greatest common factor of the freqs of the harmonics which are present)
commun over the telephone
phones typically transmit only a limited range of freqs from 300Hz to 3300Hz.
avg FF of male voice = 100Hz
avg FF of female voice = 200Hz
tf, the FF of a voice isnt transmitted
experiment
A. is it easier to “hear out” a target voice when its FF differs from the FF of the competing voice
P. taret talker speaks a sentence
. the FF of talker will be 100Hz, 106Hz, 163Hz or 200Hz
. at same time, competing talker will speak a sentence (FF=100Hz)
eg. “ready baron, go green four now”
R. accuracy increases when FF differs between voices
. increased diff = increased accuracy
. decreased accuracy = decreased FF of target voice
C. accuracy depends on the ease w/ which the harmonics of the target voice can be separated from harmonics of the competing voice. hence, accuracy depends on the similarity of the freqs of the first few harmonics in the target and the competing voices
tf, diff in pitch helps listeners to seperate concurrent sources of sound (explains the cocktail party effect)
conclusion of experimental findings
- pitch (the fundamental freq of a sound) can be used as a tool to seperate a target talker from a competing talker
- however, comp between the two talkers also happens at the lvl of harmonics
- tf, target recognition is maximal if neither the fundamental freq nor the harmonics overlap
