SOUND WAVE loudspeaker-waveform (ALYAA MAISARAH BINTI MOHMAD ROSMAN) 


       (FATIN RABBIATULADAWIAH BT SALEHUDDIN)

FUNDAMENTALS OF SOUND WAVES
-Frequency (no. of oscillations in pressure per second).
-Wavelength (distance between each successive region of high or low pressure).

LOUDNESS & PITCH

MAXIMUM PRESSURE IN A SOUND WAVE mqdefault

click to edit

SUPERSONIC & SHOCK
An object, such as a JET, s said to have supersonic speed if it travels faster than the speed of sound. Such speed defined using "Mach" number.220px-Schlierenfoto_Mach_1-2_Pfeilflügel_-_NASA

Stationary Sound Source
(Equally spaced wavelength&Frequency is the same)st

Sound source moving at the velocity lower than the speed of sound
(doppler effect takes places wavelength at the front is smaller than in the back)
mv

Speed of source= Speed of sound
(Wave fronts pile up directly in front of the source) sm

Velocity of sound < Velocity of object
(Wavefronts pile up along the side.The wave crests overlap one another and form a larger amplitude wave known as SHOCK WAVE) vs

DOPPLER EFFECT
-A change in frequency of a wave that is heard by an observer when there is relative motion between the source of wave and observer. doppler-effect-vector-illustration-labeled-educational-physical-sound-light-scheme-educational-explanation-why-waves-frequency-165141826

If SOUND SOURCE moves towards stationary observer (frequency > wavelength)
f’=f [ V sound/ Vsound-Vsource] siren_moving

If SOUND SOURCE moves away from stationary observer (frequency < wavelength)
f'= f [ Vsound / Vsound+ Vsource) b420d81d4d057d450fac99b0f54bcadd

If OBSERVER moves towards stationary sound source (frequency > wavelength)
f'=f [ Vsound + Vobserver / Vsound ] unnamed

If OBSERVER moves away from stationary sound source (frequency < wavelength) f'=f [ Vsound - Vobserver / Vsound ]

COMBINED FORMULA (Useful for when observer & source are both moving) Doppler-Equation-3

TRANVERSE AND LONGITUDINAL STANDING WAVE

STRINGED INSTRUMENTS (Many examples of stringed intruments exists (piano,guitar) when the string on the instrument is plucked, it begins to oscillate and produces a STANDING WAVE.
-Formula ( fn=n v / 2L ) (n=1,2,3,4,....) m12413.id113255

WIND INSTRUMENTS (These instruments produced sound waves in a column of air within a tube. Some example include the FLUTE & ORGAN PIPE.
-LONGITUDINAL OPEN AT BOTH ENDS (fn=n v/2L)(n=1,2,3.4....) OPEN AT BOTH END2
-LONGITUDINAL OPEN AT ONE END (fn=n v/4L) (N=1,3,5,7...) CLOSED2

DIFFRACTION & SOUND (Bending of sound around a barrier)
Picture1

CONTRUCTIVE&DESTRUCTIVE INTERFERENCE 6a14a90e6bb2c2bcb05e143816751984

SINGLE SLIT DIFFRACTION Single-Slit-Diffraction

CIRCULAR OPENING (1ST MINIMUM) slide_9

DOUBLE SLIT DIFFRACTION Picture6

LOUDNESS
-Depend on the amplitude of the sound wave
-Intensity, I (rate of energy per area)= Watts/m^2 determines loudness

PITCH
-The frequency of sound wave
-The frequency determines pitch.
-The human ear can detect an extremely wide range of intensities.
-Audible frequency 20Hz-20000Hz,Infrasonic (<20Hz),Ultrasonic (>20000 Hz)

THE SOUND LEVEL
-The human ear can detect an extremely wide range of intensities.
Range(1×10^-12 W/m^2)
-FORMULA :
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BEAT FREQUENCY= No of cycle/Time elapsed