1 perception of sound
1.1 pitch
1.2 duration
1.3 loudness
1.4 timbre
1.5 sonic texture
1.6 spatial location
perception of sound
a distinct use of term sound use in physics in physiology , psychology, term refers subject of perception brain. field of psychoacoustics dedicated such studies. historically word sound referred exclusively effect in mind. webster s 1947 dictionary defined sound as: heard; effect produced vibration of body affecting ear. meant (at least in 1947) correct response question: if tree falls in forest no 1 hear fall, make sound? no . however, owing contemporary usage, definitions of sound physical effect prevalent in dictionaries. consequently, answer same question yes, tree falling in forest no 1 hear fall make sound .
the physical reception of sound in hearing organism limited range of frequencies. humans hear sound frequencies between approximately 20 hz , 20,000 hz (20 khz), upper limit decreases age. sound refers vibrations frequencies within hearing range humans or relates particular animal. other species have different ranges of hearing. example, dogs can perceive vibrations higher 20 khz.
as signal perceived 1 of major senses, sound used many species detecting danger, navigation, predation, , communication. earth s atmosphere, water, , virtually physical phenomenon, such fire, rain, wind, surf, or earthquake, produces (and characterized by) unique sounds. many species, such frogs, birds, marine , terrestrial mammals, have developed special organs produce sound. in species, these produce song , speech. furthermore, humans have developed culture , technology (such music, telephone , radio) allows them generate, record, transmit, , broadcast sound.
noise term used refer unwanted sound. in science , engineering, noise undesirable component obscures wanted signal. however, in sound perception can used identify source of sound , important component of timbre perception (see above).
soundscape component of acoustic environment can perceived humans. acoustic environment combination of sounds (whether audible humans or not) within given area modified environment , understood people, in context of surrounding environment.
there 6 experimentally separable ways in sound waves analysed. are: pitch, duration, loudness, timbre, sonic texture , spatial location.
pitch
figure 1. pitch perception
pitch perceived how low or high sound , represents cyclic, repetitive nature of vibrations make sound. simple sounds, pitch relates frequency of slowest vibration in sound (called fundamental harmonic). in case of complex sounds, pitch perception can vary. individuals identify different pitches same sound, based on personal experience of particular sound patterns. selection of particular pitch determined pre-conscious examination of vibrations, including frequencies , balance between them. specific attention given recognising potential harmonics. every sound placed on pitch continuum low high. example: white noise (random noise spread evenly across frequencies) sounds higher in pitch pink noise (random noise spread evenly across octaves) white noise has more high frequency content. figure 1 shows example of pitch recognition. during listening process, each sound analysed repeating pattern (see figure 1: orange arrows) , results forwarded auditory cortex single pitch of height (octave) , chroma (note name).
duration
figure 2. duration perception
duration perceived how long or short sound , relates onset , offset signals created nerve responses sounds. duration of sound lasts time sound first noticed until sound identified having changed or ceased. not directly related physical duration of sound. example; in noisy environment, gapped sounds (sounds stop , start) can sound if continuous because offset messages missed owing disruptions noises in same general bandwidth. can of great benefit in understanding distorted messages such radio signals suffer interference, (owing effect) message heard if continuous. figure 2 gives example of duration identification. when new sound noticed (see figure 2, green arrows), sound onset message sent auditory cortex. when repeating pattern missed, sound offset messages sent.
loudness
loudness perceived how loud or soft sound , relates totalled number of auditory nerve stimulations on short cyclic time periods, on duration of theta wave cycles. means @ short durations, short sound can sound softer longer sound though presented @ same intensity level. past around 200 ms no longer case , duration of sound no longer affects apparent loudness of sound. figure 3 gives impression of how loudness information summed on period of 200 ms before being sent auditory cortex. louder signals create greater push on basilar membrane , stimulate more nerves, creating stronger loudness signal. more complex signal creates more nerve firings , sounds louder (for same wave amplitude) simpler sound, such sine wave.
timbre
timbre perceived quality of different sounds (e.g. thud of fallen rock, whir of drill, tone of musical instrument or quality of voice) , represents pre-conscious allocation of sonic identity sound (e.g. “it’s oboe! ). identity based on information gained frequency transients, noisiness, unsteadiness, perceived pitch , spread , intensity of overtones in sound on extended time frame. way sound changes on time (see figure 4) provides of information timbre identification. though small section of wave form each instrument looks similar (see expanded sections indicated orange arrows in figure 4), differences in changes on time between clarinet , piano evident in both loudness , harmonic content. less noticeable different noises heard, such air hisses clarinet , hammer strikes piano.
sonic texture
sonic texture relates number of sound sources , interaction between them. word texture , in context, relates cognitive separation of auditory objects. in music, texture referred difference between unison, polyphony , homophony, can relate (for example) busy cafe; sound might referred cacophony . texture refers more this. texture of orchestral piece different texture of brass quintet because of different numbers of players. texture of market place different school hall because of differences in various sound sources.
spatial location
spatial location (see: sound localization) represents cognitive placement of sound in environmental context; including placement of sound on both horizontal , vertical plane, distance sound source , characteristics of sonic environment. in thick texture, possible identify multiple sound sources using combination of spatial location , timbre identification. main reason why can pick sound of oboe in orchestra , words of single person @ cocktail party.
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