10.3 features of a sound tide (ESADD)

Since sound is a wave, we can relate the nature of sound to the nature of a wave. The an easy properties the 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 is softer (smaller amplitude) than Sound C.


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

The person ear can detect a wide selection of frequencies. Frequencies indigenous 20 come 20 000 Hz space audible come the person ear. Any kind of sound through a frequency below 20 Hz is recognized as one infrasound and also any sound with a frequency above ( ext20 000) ( extHz) is known as one ultrasound.

Table 10.2 list the varieties of part common animals compared come humans.

lower frequency (( extHz)) upper frequency (( extHz))
Humans ( ext20) ( ext20 000)
Dogs ( ext50) ( ext45 000)
Cats ( ext45) ( ext85 000)
Bats ( ext20) ( ext120 000)
Dolphins ( ext0,25) ( ext200 000)
Elephants ( ext5) ( ext10 000)

Table 10.2: range of frequencies

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Range of wavelengths

Using the information offered in Table 10.2, calculate the lower and also upper wavelengths that each species can hear. Assume the rate of sound in air is ( ext344) ( extm·s$^-1$).


The amplitude of a sound tide determines its loudness or volume. A bigger amplitude method a enlarge sound, and also a smaller amplitude way a softer sound. In figure 10.2 sound C is louder than sound B. The vibration the a source sets the amplitude of a wave. The transmits energy into the medium through its vibration. Much more energetic vibration corresponds to bigger amplitude. The molecules move back and forth much more vigorously.

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

Sound, frequency and amplitude

Textbook exercise 10.1

Study the following diagram representing a musical note. Redraw the diagram because that 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 the instruments impacts the sounds the they are able to produce. Uncover some tools that have different physical characteristics and compare their sounds. Girlfriend could:

Option 1: Vuvuzelas:

Compare the sound made by blowing v vuvuzelas of different sizes. Girlfriend will require to uncover a few different vuvuzelas. Take transforms blowing the various ones, one in ~ a time and also record which friend think is larger (amplitude), which is of greater pitch (frequency).

Option 2: Tuning forks:

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

You will need to find a few different tuning forks. Take turns tapping the various ones, one at a time and record which friend think is enlarge (amplitude), i m sorry is of greater pitch (frequency).

Option 3: Signal generator and oscilloscope

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

Function generator

The function generator allows you to regulate the loudness and frequency of the sound being produced by the speaker. It will have actually controls for amplitude and also frequency.

A role generator



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

The most usual oscilloscope controls space for amplitude, frequency, triggering, and channels. When your teacher has actually helped you gain a signal making use of the exactly channel and also triggering you will usage the amplitude and frequency controls to display the characteristics of the sound being produced.

The amplitude adjustment of an oscilloscope controls just how tall a offered voltage will show up on the screen. The purpose of this convey is the you deserve to see a very large or a very small signal ~ above the same screen.

An oscilloscope


Two various oscilloscope traces


The frequency (or time) mediate of an oscilloscope is exactly how much time will certainly a specific distance across the display screen represent. The objective of this mediate is to have the ability to see a really quickly transforming or a slowly an altering signal ~ above the same screen.

Note:The display screen of the oscilloscope will display you a transverse tide pattern. This go not average that sound waves room transverse waves but just reflects that the push being measured is fluctuating since of a pressure wave.

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