2. •
When sounds are produced,
mechanical energy travel through
air in different wavelengths.
•
Different wavelengths hit our ear in
differing frequencies.
•
Frequencies: the rate in which
different wavelengths travel
through the air (in this case, into
our ear).
b
y = a sin (bx+c) determines the frequency
3. (the rate in which the wavelengths are traveling through the air)
Frequencies are measured in the unit of Hertz (Hz).
Frequency depends on the number of periods (length of wave)
over time.
• The more periods per unit of time, the higher the frequency
• Higher frequencies equals higher pitch to the ear
• Lower frequencies equals lower pitch to the ear
•
•
y = a sin
Increase b = higher frequency
Decrease b = lower frequency
(bx+c)
4. •
Chords/combinations are more appealing when
frequencies...
•
•
•
are similar
have wave cycles that match up at
regular intervals (match on x-axis)
Note combinations with wavelength cycles that
do not match up in a pattern will create
dissonant sounds (less pleasing to the ear).
6. •
Pressure comes from the
constant movement of sound
particles
•
In the ear, pressure constantly
fluctuates up and down
•
Compressions: the high
pressure points of a sound
wave
•
Rarefactions: the low pressure
points of a sound wave
•
Rate of compressions and rarefactions indicates pressure
•
Rate of compression-rarefaction is proportional to
frequency
7. •
Humans and animals can distinguish the
different frequencies/fluctuations of
sound/pressure waves.
•
Infrasound: Vibrations lower than
human range (less than 20 Hz)
•
Ultrasound: Vibrations higher than
human range (more than 20,000Hz)
