![]() ![]() The period is simply the reciprocal of the frequency ( T = 1/ f).ĭiagrams showing the impact of sound wave frequency and amplitude on pitch and volume of sound. Figure 5 also shows the period ( T) of the wave, which is the time it takes for one complete wave to pass a given point. On average, the frequency range for human hearing is from 20 Hz at the low end to 20,000 Hz at the high end. The higher the frequency, the higher the perceived pitch. The frequency of a sound wave determines the pitch of a sound. These graphs show how the pressure at a single point in space (a fixed distance) changes over time. Note that the graphs in this figure show time on the x-axis, not distance as in Figure 3. Figure 5 (on the left) illustrates examples of sound waves of two different frequencies. Frequency is measured in Hertz (Hz), which is the number of cycles per second. This is dependent on how fast the object that creates the sound wave (such as the vocal folds) are vibrating. The frequency of a wave describes how many cycles of the wave occur per unit of time. In addition to speed, you can describe waves by their frequency, period, and amplitude (Figure 5). To answer this question, we have examine the properties of a sound wave in more detail. This explains how we can make sounds with our voice and how we can hear sounds, but it does not explain why there are so many different sounds with various pitches and volumes. Our ear translates sound waves into a sound that we can hear. The ear drum vibrates air trapped in the inner ear and a nerve sends a signal to the brain which can decipher the vibrations as different sounds.įigure 4. When sound waves enter a human ear they travel past the outer ear until they hit the ear drum. ![]() This lesson focuses on these aspects of NGSS Three Dimensional Learning: Use mathematical representations to describe a simple model for waves that includes how the amplitude of a wave is related to the energy in a wave. This lesson helps students prepare for these Next Generation Science Standards Performance Expectations: ![]() Measure sound intensities of sounds and draw graphs showing sound levels based on measured data.Explain how the amplitude of a sound wave is related to its sound intensity (volume or loudness).Recognize and describe the patterns and characteristics of a sound wave (amplitude, frequency).How loud are your students when doing independent work, having a group discussion, or listening to their teacher? Based on your students' data, you will determine as a class which sound levels are ideal for each scenario and create a classroom poster that reminds your students of these sound levels throughout the school year. Using a mobile phone and a sensor app, your students will measure and graph the sound levels in your classroom for different working scenarios. Do you feel like it is always too loud in your classroom? In this lesson you can find out exactly how loud it is. ![]()
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