Experiment 5: Introduction to Sound

Purpose: The purpose of this experiment is verify the characteristics of sound waves by observing the wave pattern, frequencies, periods, amplitudes, and wavelengths.

Formulas and Derivations:

Procedure:

Figure 1: Experimental setup with logger pro

Figure 2: Producing sound waves into the microphone

DATA and ANALYSIS:

Human Sound
.05 seconds	Graph	# of Waves	Period (s)	Frequency (Hz)	Wavelength (m)	Amplitude (Arbitrary)
Person A	1	22	0.0023± 0.0015	440 ± 5	0.773 ± 0.05	0.697 ± 0.15
Person B	2	6	0.0083 ± 0.0015	120 ± 5	2.83 ± 0.05	0.123 ± 0.15

Tuning Fork
.05 seconds	Graph	# of Waves	Period (s)	Frequency (Hz)	Wavelength (m)	Amplitude (Arbitrary)
Not Loud	3	13	0.00385±0.0015	260 ± 5	1.31 ± 0.05	0.02 ± 0.015
Loud	4	13	0.003845±0.0015	260 ± 5	1.31 ± 0.05	0.055 ± 0.015

Human sound with 10t
.5 seconds	Graph	# of Waves	Period (s)	Frequency (Hz)	Wavelength (m)	Amplitude (Arbitrary)
Person A	1H	74	0.0068±0.0015	148 ± 5	2.29 ± 0.05	0.457 ± 0.015

Sound Pressure vs. Time

Graph 1: Person 1 Human Voice 0.05 seconds

a) For graph 1 the human voice that was recorded would be considered periodic because of the repeating pattern it has as the time increases. Although this graph is not a perfect sinusoidal, it can be still be defined as periodic.

b) The number of waves determined are derived by counting the number of crests in the given time interval.

c) The probe collected data as fast as Kobe Bryant on a fast break.

d) Period was determined by dividing the number of seconds by the number of cycles. 

e) The frequency was determined by taking the inverse of the period that was calculated.

f) The length of the wavelength was as long as half a meter stick or the height of the table.

g) The amplitude of the graph was determined by observing the graph itself and taking the y value (arbitrary) of the crest.

Sound Pressure vs. Time

Graph 1H: Person 1 human sound .5 seconds

Sound Pressure vs. Time

Graph 2: Person 2 human sound 0.05 seconds

Sound Pressure vs. Time 

Graph 3: Tuning fork against "not loud" object

Sound Pressure vs Time

Graph 4: Tuning fork against "loud" object

CONCLUSION:

The five graphs of the different variations of sounds produced help draw certain verification of the principle of sound. Comparing graph 1 to graph 1H, where the sound ran 10 times longer; the amplitude, frequency, period, and wavelength all had different values. The results showed a higher period and lower amplitude and frequency. The number of cycles in the graph was 3 times as graph 1. 

Between graph 1 and graph 2 there were significant differences in the characteristics of the waves.

Graph 1 had a more than twice the amount of waves in the same time interval. This resulted in a higher period for the second person in graph 2. Graph 2 also showed a much lower frequency of 120 Hz compared to 440 Hz from person A in Graph 1. The wavelength was also considerably high for person B, which makes sense since the frequency was much lower. The inverse relationship between the wavelength and frequency give that characteristic. The amplitude for person A also gives a smaller value than person A.  The amplitude is measured in arbitrary for the sound pressure. This means that person A had a much higher sound pressure resulting in a louder sound. Person A did seem to have a more high frequency sound giving such characteristics in the graphs.

Graph 3 showed a sinusoidal wave which a human voice could not produce. The tuning fork had a consistent frequency and wavelength. Conversely the human voice had different frequency and wavelength for every trial whether it was a high pitch low pitch unlike the tuning fork. The differences between graph 3 and 4 showed the consistency of the wavelength and frequency no matter the loudness of the sound. However the only difference between the two was the amplitude. The louder  the sound, the higher the amplitude. To make the sound softer we hit the object softer on an eraser than harder on the back end of a shoe. This changed the value of the amplitude depending on the loudness on graph 4. Graph 4 had a louder sound and produced a higher amplitude which verifies the relationship between loudness and amplitude. 

Based on all the observations made it can be concluded that sound waves studied and equations used can all be verified. The relationship between loudness and amplitude was also verified as well as the relationship between higher and lower frequency.