Consider the following sound waves marked A , B , C and D : Which two waves represent sounds of the same loudness but different pitch?

The waves A and D same loudness but different pitch. Loudness depends on amplitude which is the maximum displacement of the particle from its mean position. In the given figure A and D , wave is covering two blocks up from mean position and similarly two blocks down from mean position. These two wave have the different pitch as they have different frequency. The number of oscillations covered by both the waves in unit time is different. So, they have the different pitch. In other word, we can also say that these two waves covering different wavelengths in same time, so, they have different pitch.

Consider the following sound waves marked A , B , C and D : Which two waves represent sounds of the same frequency but different loudness?

The waves A and B have the same frequency and different loudness. We know that frequency is defined as number of oscillations in per unit time. In both the wave, number of cycles are same in same time or wavelengths of the waves are also same.Therefore, these two waves have the same frequency. The loudness of sound depends on the amplitude of the wave. An amplitude is the maximum displacement of particles of medium from mean position. Here, wave A is covering two blocks up and two blocks down from mean position while wave B has one block up and down from means position. Therefore, these two waves have different amplitude.

Consider the following sound waves marked A , B , C and D : Which vibrating body/bodies could have generated the sound waves shown here?

Tuning forks or strings may produce the sound waves shown here because individually these waves are producing sound of same frequency which is called tone. Also, from the frequencies and wavelengths observed they are very small sounds which can be produced by the commonly used sound experimenting objects.