OBJECTIVE MEASUREMENT OF THE CHARACTERISTICS OF SOUND
OBJECTIVE:
The student will make measurements of the sine wave, analyzing its behavior with varying frequency and amplitude, as well as the existence of the audible range.
previous investigation.
physical properties of sound:
Wavelength: The distance traveled by a wave in a cycle.
Period: The time it takes for a wave to travel a full cycle.
Frequency: Number of cycles occurring in a second.
Size: Maximum value reached by an oscillation cycle.
Human Ear: The human ear is a sound analysis system extremely complex, which is capable of receiving sound in a wide range of intensities and frequencies. It consists of three parts:
The outer ear, middle ear and inner ear.
audible frequency range: The audible spectrum can be subdivided according to the tones:
1. Bass (low frequencies, corresponding to the first 4 octaves, ie from 16 Hz to 256 Hz).
2. Midrange (midrange octaves for fifth, sixth and seventh, that is, 256 Hz to 2 kHz).
3. Treble (high frequencies, corresponding to the last three octaves, that is, 2 kHz to just over 16 kHz). DEVELOPMENT OF PRACTICE
1 .- Build the circuit of Figure crashing the connection between the audio generator and oscilloscope are parallel generator using audio, making nine readings by measuring its period, frequency, peak voltage, peak voltage and peak wavelength through the oscilloscope.
frequency selection in choose three low-range frequencies, three mid-range frequencies and three high ranking. Draw
corresponding waveform Waveform
FREQ. Vol V peak peak period peak wavelength range under
Vrms 80Hz 1.9V 3.8v 12.68ms 331 m / s
120Hz 1.3V 1.9V 3.8V 8.5ms 331 m / s 4.9ms 200Hz
1.35v 1.9V 3.8v 331 m / s 1.35v
Midrange 320Hz 1.9V 3.8v 3.09ms 331 m / s 1.9ms 500Hz
1.34v 1.9V 3.8v 331 m / s 1.34v 988ms
1Khz 1.9V 3.8v 331 m / s 1.34v
2.8 kHz High Range 1.9V 3.8v 368Ms 331 m / s
1.32v 3.8v 1.9V
5KHz 203Ms 331 m / s 1.32v
12KHz
85MS 1.9V 3.8v 331 m / s 1.32v
2. - Among the audio generator and oscilloscope connected in parallel to stand by the alternating voltage function.
In the same way as above, take reading of nine frequencies, measured in each of the alternating voltage.
there a difference between measurement of voltage measured by oscilloscope with respect to the measured per millimeter if applicable explain why.
A PEAK PEAK VOLTAGE FREQUENCY VOLTAGE MULTIMETER OSCILLOSCOPE
80 hz
v 3.74 v 1.3 v 1.3 3.74 120 hz 200 hz
v 3.74 v 1.3 v 2.8 v
320 hz 500 hz
1,004 v 0,998 v
2.8 V 1 kHz 0955 v 2.7 v 2.8 kHz
0853 v 2.76 v 2.78 v
5 kHz 12 kHz
0.6 v 0.3 v 2.8 v
there a difference between the voltages measured by the voltmeter only measures voltage rms.
3 .- Build the circuit in the figure below. Use the ARCA miniplug connector and connect the output of portable audio equipment. Observe and draw
waveform that is displayed on the oscilloscope.
Take voltage reading through the meter. Enter
comments: It is very random variable and is very difficult to determine a period, frequency or amplitude.
4. - Place the signal generator in sine wave function at a frequency of 1 kHz slowly varies the voltage from a minimum to find the value at the start the tone. Later make a sweep from 20 Hz to 20 kHz. (Without changing the voltage).
Repeat the above procedure now finding the maximum voltage that the speaker can withstand without distorting the tone of 1 KHz. Similarly make a sweep without changing the voltage frequency.
Record your observations: What
feeling seemed sound when swept from 20 Hz to 20 kHz?
By varying the sound frequency is modified in a low tone to high tone.
Minimum Voltage: 014 v
Frequency: 86 Hz
Maximum Voltage: 384 v
Frequency: 16 kHz
Conclusions:
We observed that the tone of the sound depends on the frequency and voltage. Was also like a melody that is the union of various musical instruments that generate a signal different each to see on the oscilloscope can not identify its elements as the total signal is very uncertain.
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