10.3 qualities of a sound wave (ESADD)

Since sound is a wave, we deserve to relate the nature of sound come the nature of a wave. The an easy properties that sound are: pitch, loudness and tone.

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Figure 10.2: Pitch and loudness the sound. Sound B has actually a lower pitch (lower frequency) than Sound A and also is softer (smaller amplitude) than Sound C.


The frequency of a sound tide is what her ear understands as pitch. A higher frequency sound has actually a greater pitch, and also a reduced frequency sound has actually a reduced pitch. In number 10.2 sound A has actually a greater pitch than sound B. Because that instance, the chirp of a bird would have actually a high pitch, yet the roar of a lion would have a short pitch.

The person ear deserve to detect a wide range of frequencies. Frequencies indigenous 20 to 20 000 Hz room audible come the human ear. Any type of sound v a frequency below 20 Hz is recognized as an infrasound and also any sound with a frequency above \(\text20 000\) \(\textHz\) is known as an ultrasound.

Table 10.2 lists the arrays of some common pets compared come humans.

lower frequency (\(\textHz\)) upper frequency (\(\textHz\))
Humans \(\text20\) \(\text20 000\)
Dogs \(\text50\) \(\text45 000\)
Cats \(\text45\) \(\text85 000\)
Bats \(\text20\) \(\text120 000\)
Dolphins \(\text0,25\) \(\text200 000\)
Elephants \(\text5\) \(\text10 000\)

Table 10.2: range of frequencies

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Range the wavelengths

Using the information provided in Table 10.2, calculate the lower and upper wavelengths that each varieties can hear. Assume the rate of sound in air is \(\text344\) \(\textm·s$^-1$\).


The amplitude of a sound wave determines the loudness or volume. A larger amplitude method a larger sound, and a smaller sized amplitude way a softer sound. In number 10.2 sound C is louder than sound B. The vibration the a source sets the amplitude the a wave. The transmits energy into the tool through that vibration. More energetic vibration corresponds to bigger amplitude. The molecules move back and forth an ext vigorously.

The loudness of a sound is also determined by the sensitivity the the ear. The human ear is more sensitive to part frequencies than to others. The volume we receive thus depends on both the amplitude that a sound wave and also whether that is frequency lies in a an ar where the ear is an ext or less sensitive.

Sound, frequency and amplitude

Textbook practice 10.1

Study the complying with diagram representing a music note. Redraw the diagram for a note

with a greater pitch

that is louder

that is softer


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Comparing sound generating instruments

The size and also shape that instruments impacts the sounds that they space able to produce. Uncover some instruments that have various physical characteristics and compare their sounds. You could:

Option 1: Vuvuzelas:

Compare the sound made by blowing with vuvuzelas of different sizes. You will need to find a couple of different vuvuzelas. Take turns blowing the different ones, one at a time and record which friend think is larger (amplitude), which is of greater pitch (frequency).

Option 2: Tuning forks:

Compare the sounds developed by tapping tuning forks of different sizes.

You will need to uncover a couple of different tuning forks. Take transforms tapping the different ones, one at a time and also record which friend think is larger (amplitude), which is of greater pitch (frequency).

Option 3: Signal generator and also oscilloscope

Use a role generator connected to a speak to produce sounds of various frequencies and also amplitudes and also use a microphone linked to an oscilloscope to screen the characteristics of the various sounds produced.

Function generator

The role generator permits you to regulate the loudness and also frequency that the sound being developed by the speaker. It will have controls because that amplitude and frequency.

A duty generator



The microphone have the right to then choose up the sound and convert it to an electrical signal which deserve to be presented on the oscilloscope.

The most common oscilloscope controls room for amplitude, frequency, triggering, and also channels. Once your teacher has helped you get a signal using the correct channel and also triggering you will use the amplitude and also frequency controls to display the attributes of the sound gift produced.

The amplitude convey of an oscilloscope controls how tall a given voltage will appear on the screen. The purpose of this mediate is that you can see a very large or a very little signal top top the exact same screen.

An oscilloscope


Two various oscilloscope traces


The frequency (or time) adjustment of one oscilloscope is exactly how much time will certainly a specific distance throughout the display represent. The purpose of this mediate is to have the ability to see a very quickly transforming or a slowly transforming signal on the same screen.

Note:The display screen of the oscilloscope will show you a transverse wave pattern. This go not typical that sound waves room transverse waves yet just reflects that the press being measure up is fluctuating because of a push wave.

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You will be able to experiment with different amplitudes and frequencies making use of the duty generator and also see what affect the changes have top top the waveform picked up by the microphone.