Light, Sound and Waves

Range of hearing

Classroom Activity for 5-11 11-14 Supporting Physics Teaching

What the Activity is for

Exploring the audible range.

The aim of this activity is to reinforce the relationship between pitch and frequency, and to give some feeling for the numbers involved when measuring frequencies. Measuring something about themselves also allows children to make real connections to the topic.

What to Prepare

  • A computer running software that allows you generate and play back different frequencies. In all cases pure notes of a single frequency are best.

What Happens During this Activity

Play back a note of audible frequency and loudness. Ask the class to put their hand up if they hear the note. Now move progressively to higher and higher frequencies. Instruct the pupils to keep their hands raised until they can no longer hear the sound. In this way it is possible to identify the upper threshold of frequency response of the ear and the variation in this figure between members of the class. Repeat the procedure for the lower frequency threshold, moving down through the frequency scale.

At the upper end of the spectrum you might want to turn down the loudness control so that there is actually no sound! This little trick will weed out those pupils who are a little too enthusiastic in their claims. You might even want to discuss using this approach to make the findings of the demonstration more reliable. It has parallels with placebo testing in medicine.

appears in the relation v=fλ E=hf f=1/T (f_o)/(f_s)=(v+v_o)/(v-v_s)
is used in analyses relating to Progressive Wave
has the special case Resonant Frequency Natural Frequency
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