September 10, 2008
Speech Science
Characteristics of Sound Waves
Interference can affect perception of sound
Reverberation
Sound lasts slightly longer because of interference
Can increase the intensity of the incident sound reaching a listener
Sound Wave 1 + Sound Wave 2 = Sound Wave 1+2
Too much reverberation can interfere with speech understanding
Reflective Surfaces
Vowel sounds are reflected because of their lower frequency
This leads the vowels to fight with the consonants
Pure tone, sinusoid, sine wave
If you stick a pencil to a tuning fork and have it draw the wave, it would
be the same amplitude and frequency over and over
Simple Harmonic Motion (SHM)
One frequency
Complex Waves
Have more than one frequency
More common than pure tones
Periodic and aperiodic
Periodic complex sounds
Lowest frequency known as fundamental frequency
Whole multiples of the fundamental
Remaining frequencies known as harmonic frequencies
Complex waves can be represented by the sum of its component freq
Aperiodic complex sound (white noise)
Two or more frequencies
Not systematically related
Contains broad range of frequencies
Two types
Can be prolonged
Transient brief in duration
Speech Sounds
Considered complex
Vowels are complex periodic
Voiced Consonants
Combination of both periodic and aperiodic
Voiceless consonants – complex aperiodic
Both continuous and transient productions
Line Spectrum
Lets you visualize harmonics
Represented by vertical line
Height shows amplitude in dB