What term describes the degree of attenuation per centimeter of sound propagation?

• A. Attenuation rate
• B. Attenuation coefficient
• C. Absorption coefficient
• D. Scattering coefficient

Answer: (B)

Attenuation per unit distance describes how quickly sound loses intensity as it travels. The term that captures this rate per centimeter for a given frequency is the attenuation coefficient. In ultrasound physics this is usually denoted alpha and expressed in dB per centimeter, reflecting how many decibels of loss occur for each centimeter of travel. It encompasses the overall loss due to both absorption and scattering as the wave propagates. The absorption coefficient, by contrast, describes how much energy is absorbed per unit length, but doesn’t alone represent the total attenuation including scattering. The scattering coefficient describes energy redirected out of the main beam, another contributor but not the total attenuation rate. Attenuation rate isn’t the standard descriptor used here, so attenuation coefficient is the precise term for attenuation per centimeter.