Biology
Home > Biology > Options > Communication > Communication: 5. Sound communication
9.5 Option – Communication: 5. Sound communication
| Syllabus reference (October 2002 version) | ||
|---|---|---|
5. Sound is also a very important
communication medium for humans and other animals |
Students learn to:
|
Students: |
Extract from Biology Stage 6 Syllabus (Amended October
2002). © Board of Studies, NSW.
[Edit:17 Aug 04]
Background: Sound is a form of energy that travels in waves. We can compare sound waves by determining their frequency. Frequency is the number of waves that are produced per second, and is related to the pitch of a sound. Wavelength is the distance between successive crests of a wave. Sound requires a medium such as a solid, liquid or gas through which to travel. Sound cannot travel through a vacuum.
explain why sound is a useful and versatile form of communication
- Many animals use sound to communicate with each other. Sound is a versatile form of communication because animals can vary the nature of the sounds they produce. For example, animals may produce sounds of varying pitch and loudness to communicate different information.
- Sound is also useful both day and night. It travels over long distances and can go around corners. The sender does not have to be visible to the receiver.
plan and perform a first-hand investigation to gather data to identify the relationship between wave-length, frequency and pitch of a sound
Background
A Cathode Ray Oscilloscope (CRO) is a device which is used to display the nature of waves on a screen. You should have done an experiment using an oscilloscope .You can find instructions for setting up a CRO at Using an Oscilloscope 
. Doctronics Educational. If you do not have access to a CRO download the oscilloscope from this webpage and enter sound through your computer microphone. Virtual oscilloscope . Peter Debik.
- Short wavelength waves have high frequencies and higher pitch. Long wavelength waves have low frequencies and lower pitch.
- Plan the investigation to identify the relationship between wavelength, frequency and pitch.
- To perform this investigation you could input sounds from a musical instrument or other source of sound into the CRO or virtual CRO via a microphone. The CRO will convert the sounds to a voltage which can be displayed on the screen. Varying the pitch of the sound will cause a change in the frequency and wavelength of the wave displayed.
- Gather the first hand data by using appropriate technology, either a CRO or the digital CRO from the Internet.
- You could record your results as a series of diagrams. Prepare diagrams to compare sounds of high pitch to those of low pitch. What happens to wavelength and frequency as pitch increases? Use this link as a starting point.
Pitch and frequency The Physics Classroom, Glenbrook
High School District 225, Glenfield, Illinois, USA.
explain that sound is produced by vibrating objects and that the frequency of the sound is the same as the frequency of the vibration of the source of the sound
- Sound is a form of energy produced by an object that vibrates, moving backwards and forwards. The vibrating object causes nearby air molecules to vibrate back and forth, and these molecules cause others to vibrate.
- This results in a compression wave travelling through the air.
- The frequency of the vibration of air molecules is the same as the frequency of the vibrating object.
gather and process information from secondary sources to outline and compare some of the structures used by animals to produce sound
- Gather information from a range of
resources including popular scientific journals, CD ROMs
and the Internet.
- Animals use a range of structures to produce sounds.
Process the information by preparing a brief
outline to show how some animals do this.
Some animals of interest include dolphins, whales,
manatees, cicadas, rattlesnakes, bats, frogs and
birds.
- A table like the one below is an effective tool to assist you to record information. Most mammals use their breathing systems to make sounds.
| Animal
|
Description of structure used to
produce sound
|
|---|---|
|
bats |
ultrasonic signals from the bat's larynx |
|
grasshoppers |
friction of the back legs or rubs the veins on the wings together (stridulating) |
|
frogs |
male frogs vocalise by squeezing their lungs while shutting their nostrils and mouth, air flows over their vocal cords and into their vocal sacs |
|
fish |
some fish vibrate their swim bladders to create sound |
Compare these structures. How are they
similar? How are they different?
A useful starting point is the web site
Biosonar University of
Bristol, UK.
- Animals use sounds for a variety of purposes. These
include attack, escape, identification, warn off predators,
mark territory, attract mates and for locating each
other.
- Secondary sources you could use include library books or the Internet. Good examples to look for include gulls, bees, dolphins, humpback whales and the great apes.
A useful starting point is the web site
Bioacoustica
Wildsong, Alnwick, Northumberland, UK.
outline the structure of the human larynx and the associated structures that assist the production of sound
- Structures which assist in the production of sound are shown in the diagram below.
The larynx or voice box lies directly below the tongue and
soft palate. Inside the larynx are the vocal cords, which
consist of muscles which can adjust pitch by altering their
position and tension. Together, the larynx, tongue and hard
and soft palate make speech possible. When air passes over
the vocal cords in the larynx, they produce sounds that can
be altered by the tongue, together with the hard and soft
palate, the teeth and the lips.
Here is a useful starting point,
Vocal Sound Production HyperPhysics, R Nave, Department
of Physics and Astronomy, Georgia State University, Georgia,
USA.
|