Prof. Greg Francis 1 PSY 310: Sensory and Perceptual Processes Purdue University Sound Quality PSY 310 Greg Francis Lecture 32 Name that tune! Purdue University Sound perception An integral part of our modern world Billions are spent annually on Creation of new sounds or sound sequences (music) Equipment to play sounds (iPods, speakers, stereo systems, surround sound theater systems) Buildings to present sounds (opera houses, symphony halls, recording studios) People who are gifted with sound (singers, musicians, song writers) This is true all over the world Much of the emphasis is to get quality sound But what does this mean?
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Prof. Greg Francis
1PSY 310: Sensory and Perceptual Processes
Purdue University
Sound Quality
PSY 310
Greg Francis
Lecture 32
Name that tune!
Purdue University
Sound perception
An integral part of our modern world
Billions are spent annually on Creation of new sounds or sound sequences (music)
Equipment to play sounds (iPods, speakers, stereosystems, surround sound theater systems)
Buildings to present sounds (opera houses, symphonyhalls, recording studios)
People who are gifted with sound (singers, musicians,song writers)
This is true all over the world
Much of the emphasis is to get quality sound But what does this mean?
Prof. Greg Francis
2PSY 310: Sensory and Perceptual Processes
Purdue University
Quality terms For stereo systems, many terms used to describe quality have to
do with the frequencies of sound that are generated and/or thelocation of sounds
A system cannot produce all frequencies equally well
Here’s some common terms for stereo speakers and what theymean
Forward (Recessed): vocals, male and female, tend to be verypresent (absent), located in front (behind) the speakers
Spacious, airy, open: the sense of space present around theinstruments and singers
Closed, muted, dry: indicate the midrange and treblefrequencies are rolled off or depressed and dull
Rich: full, rounded sound with lots of deep, sonorous bass
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Quality terms Sibilant: the speaker has a midrange/treble peak that
emphasizes the "sss" and "ttt" sounds of singers’ vocals
Strident: way too much treble output, making brass and stringsound shrill or harsh
Thin: means the speaker has little or no bass output
Boomy: has too much bass that dominates its sound
Punchy: powerful upper bass, like a disco, but no really deepbass
Muddy: the midrange isn’t clear; that it’s hard to separate thedistinct contributions of male and female singers in a chorus
Suck-out: valley or other uneven response in mid-rangefrequencies
Nasal: what a midrange peak does to vocals, like what happensto your voice when you cup your hands around your mouth whileyou’re speaking.
Prof. Greg Francis
3PSY 310: Sensory and Perceptual Processes
Purdue University
Music
We already noted that different instruments sounddifferent in large part because they include sounds offrequencies other than the “main” sound
In addition, notes on an instrument include:
Attack: the buildup of sound at the beginning of the tone
Decay: the decrease in sound at the end of a tone
We are very sensitive to these aspects of sound, even ifwe don’t know what we are sensitive to
Johann Sebastian Bach. The Well-Tempered Clavier, Book 1,Prelude 1 (in C major)
Demonstration of piano
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Architectural acoustics Rooms where sound is very important must be designed to
promote quality sound
Need to avoid echo and problem reverberations
It’s a difficult problem, and expensive to repair
Often start with a model (1:50 scale)
Present sounds of different frequencies and measure the sound atdifferent places in the model
Prof. Greg Francis
4PSY 310: Sensory and Perceptual Processes
Purdue University
Architectural acoustics A sound (like a gunshot) at the stage has
multiple effects
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Architectural acoustics An acoustical engineer can identify which part of
the hall contributes to different reverberations andintroduce new elements to stop echo
Prof. Greg Francis
5PSY 310: Sensory and Perceptual Processes
Purdue University
Architectural acoustics You want some
reverberation,else the soundseems “flat”
Different parts ofthe hallcontribute to thereverberations
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Architectural acoustics The models can
match theactual structurequite well
Prof. Greg Francis
6PSY 310: Sensory and Perceptual Processes
Purdue University
Auditory grouping We noted that sounds all come together on the basilar
membrane
How do we track one sound stream?
Similar to the issue faced by visual grouping
Gestalt laws
Auditory stream segregation
Identification of different perceptual streams of sounds
Location: sounds from the same place, come from the samesource
Similarity of timbre (complex sound): sounds of similar timbrecome from the same source
Similarity of pitch (Pitch demo): similar pitches come from thesame source
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Auditory grouping Temporal proximity: sounds in rapid progression tend to be
from the same source
Onset and offset: sounds that stop and start at different timestend to be from different sources
Good continuation (Demo, Leyenda): sounds that stay constantor change smoothly are often produced by the same source
Experience (Mystery song): you can perceptually group soundstogether if know how they should be grouped
Prof. Greg Francis
7PSY 310: Sensory and Perceptual Processes
Purdue University
Vision and audition Often times vision and audition work together to produce a
unified perceptual experience
Vision can help guide auditory grouping
Sound can help guide visual grouping
Sometimes they conflict
McGurk effect demo
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Conclusions Lots of issues in sound quality
Complicated engineering
Involve both physical space
Temporal grouping
Prof. Greg Francis
8PSY 310: Sensory and Perceptual Processes
Purdue University
Next time
Review for Exam 3
Take exam 3
Finish up the course with
Touch
Smell
Taste
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