The only acoustic parameter that is determined by both the source and the medium.

The only acoustic parameter that is determined by both the source and the medium.

• A. Frequency
• B. Wavelength
• C. Amplitude
• D. Intensity

Answer: (B)

Wavelength is determined by both the source and the medium because it is the distance between successive peaks, which depends on how fast the wave travels in the medium and how often the source pushes out waves. The relationship is lambda = c / f, where c is the speed of sound in the medium and f is the source frequency. The source sets the frequency, while the medium sets the speed. Change either one, and the wavelength changes accordingly. For example, with the same source frequency, moving from air (slower c) to water (faster c) increases the wavelength. The other options don’t require both factors in the same fundamental way. Frequency is set by the source (the medium doesn’t determine it in typical propagation). Amplitude and intensity depend on how strongly the source drives the wave and how the medium absorbs or scatters energy, so while the medium can affect them, they’re not defined by the combination of source and medium in the same direct, shared equation as wavelength.

Wavelength is determined by both the source and the medium because it is the distance between successive peaks, which depends on how fast the wave travels in the medium and how often the source pushes out waves. The relationship is lambda = c / f, where c is the speed of sound in the medium and f is the source frequency. The source sets the frequency, while the medium sets the speed. Change either one, and the wavelength changes accordingly. For example, with the same source frequency, moving from air (slower c) to water (faster c) increases the wavelength.

The other options don’t require both factors in the same fundamental way. Frequency is set by the source (the medium doesn’t determine it in typical propagation). Amplitude and intensity depend on how strongly the source drives the wave and how the medium absorbs or scatters energy, so while the medium can affect them, they’re not defined by the combination of source and medium in the same direct, shared equation as wavelength.