10.3 features of a sound tide (ESADD)

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

You are watching: The pitch of a sound is determined by


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


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

The human being ear can detect a wide selection of frequencies. Frequencies from 20 to 20 000 Hz room audible come the human ear. Any type of sound through a frequency below 20 Hz is recognized as an infrasound and any sound v a frequency above \\(\\text20 000\\) \\(\\textHz\\) is recognized as an ultrasound.

Table 10.2 lists the varieties of part common pets compared to 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 that wavelengths

Using the information offered in Table 10.2, calculation the lower and upper wavelengths that each species can hear. I think the rate of sound in air is \\(\\text344\\) \\(\\textm·s$^-1$\\).


The amplitude that a sound wave determines its loudness or volume. A larger amplitude means a larger sound, and also a smaller amplitude way a softer sound. In figure 10.2 sound C is louder 보다 sound B. The vibration of a resource sets the amplitude that a wave. The transmits energy into the medium through that vibration. More energetic vibration synchronizes to bigger amplitude. The molecule move back and forth much more vigorously.

The loudness of a sound is additionally determined by the sensitivity the the ear. The human being ear is more sensitive to part frequencies 보다 to others. The volume us receive therefore depends top top both the amplitude that a sound wave and also whether its frequency lies in a an ar where the ear is more or much less sensitive.

Sound, frequency and also amplitude

Textbook exercise 10.1

Study the following diagram representing a musical note. Redraw the diagram for a note

with a greater pitch

that is louder

that is softer


Solution not yet available

Comparing sound generating instruments

The size and shape of instruments influences the sounds the they space able come produce. Discover some instruments that have different physical characteristics and compare their sounds. Friend could:

Option 1: Vuvuzelas:

Compare the sounds made by blowing v vuvuzelas of various sizes. Friend will need to find a few different vuvuzelas. Take turns blowing the various ones, one in ~ a time and record which girlfriend think is enlarge (amplitude), which is of greater pitch (frequency).

Option 2: Tuning forks:

Compare the sounds produced by tapping tuning forks of various sizes.

You will require to uncover a few different tuning forks. Take transforms tapping the various ones, one at a time and record which you think is larger (amplitude), i beg your pardon is of higher pitch (frequency).

Option 3: Signal generator and oscilloscope

Use a function generator linked to a speaker to develop sounds of different frequencies and amplitudes and use a microphone linked to an oscilloscope to display screen the qualities of the various sounds produced.

Function generator

The duty generator enables you to manage the loudness and also frequency the the sound being produced by the speaker. It will have controls because that amplitude and also frequency.

A role generator



The microphone can then choose up the sound and convert it come an electric signal which can be displayed on the oscilloscope.

The most typical oscilloscope controls are for amplitude, frequency, triggering, and also channels. Once your teacher has helped you obtain a signal making use of the exactly channel and also triggering you will use the amplitude and also frequency controls to display the features of the sound gift produced.

The amplitude convey of one oscilloscope controls how tall a provided voltage will show up on the screen. The purpose of this mediate is the you deserve to see a very large or a very small signal on the same screen.

An oscilloscope


Two various oscilloscope traces


The frequency (or time) convey of an oscilloscope is exactly how much time will a particular distance throughout the display screen represent. The purpose of this mediate is to be able to see a very quickly an altering or a slowly an altering signal on the exact same screen.

Note:The screen of the oscilloscope will present you a transverse wave pattern. This go not median that sound waves room transverse waves yet just reflects that the push being measure is fluctuating due to the fact that of a pressure wave.

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You will be able to experiment with different amplitudes and frequencies using the role generator and also see what impact the changes have on the waveform choose up by the microphone.