10.3 features of a sound wave (ESADD)

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

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


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

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

Table 10.2 lists the arrays 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: variety of frequencies

temp message

Range of wavelengths

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


The amplitude the a sound tide determines its loudness or volume. A bigger amplitude method a larger sound, and also a smaller sized amplitude method a softer sound. In number 10.2 sound C is louder 보다 sound B. The vibration of a source sets the amplitude of a wave. That transmits energy into the medium through its vibration. More energetic vibration corresponds to bigger amplitude. The molecule move ago and forth an ext vigorously.

The loudness of a sound is also determined through the sensitivity the the ear. The human ear is an ext sensitive to part frequencies than to others. The volume we receive therefore depends ~ above both the amplitude of a sound wave and whether the frequency lies in a region where the ear is much more or much less sensitive.

Sound, frequency and also amplitude

Textbook practice 10.1

Study the complying with 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 also shape that instruments influences the sounds the they are able come produce. Uncover some instruments that have various physical characteristics and compare your sounds. Friend could:

Option 1: Vuvuzelas:

Compare the sounds made by blowing through vuvuzelas of various sizes. Friend will need to uncover a couple of different vuvuzelas. Take transforms blowing the different ones, one in ~ a time and record which you think is louder (amplitude), which is of greater pitch (frequency).

Option 2: Tuning forks:

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

You will need to uncover a couple of different tuning forks. Take turns tapping the various ones, one in ~ a time and record which girlfriend think is louder (amplitude), i beg your pardon is of higher pitch (frequency).

Option 3: Signal generator and also oscilloscope

Use a function generator associated to a speak to produce sounds of various frequencies and also amplitudes and also use a microphone linked to one oscilloscope to display screen the features of the various sounds produced.

Function generator

The duty generator allows you to manage the loudness and also frequency of the sound being developed by the speaker. The will have actually controls because that amplitude and also frequency.

A duty generator



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

The most usual oscilloscope controls space for amplitude, frequency, triggering, and channels. As soon as your teacher has helped you get a signal using the exactly channel and also triggering you will use the amplitude and also frequency controls to display screen the qualities of the sound being produced.

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

An oscilloscope


Two different oscilloscope traces


The frequency (or time) convey of one oscilloscope is just how much time will certainly a details distance throughout the display screen represent. The purpose of this adjustment is to be able to see a an extremely quickly transforming or a slowly an altering signal on the very same screen.

Note:The display of the oscilloscope will show you a transverse wave pattern. This walk not mean that sound waves are transverse waves however just shows that the press being measure up is fluctuating since of a push wave.

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You will be able to experiment with different amplitudes and also frequencies making use of the duty generator and see what impact the transforms have ~ above the waveform choose up through the microphone.