Which of the following pairs correctly match the acoustic variable with its unit?

• A. Pressure – pascals; Density – kilograms per cubic centimeter; Distance – centimeters
• B. Pressure – meters per second; Density – kilograms per cubic centimeter; Distance – meters
• C. Pressure – pascals; Density – kilograms per cubic meter; Distance – feet
• D. Pressure – newtons; Density – kilograms per liter; Distance – kilometers

Answer: (A)

Understanding units for acoustic variables means pairing each quantity with its proper unit. Pressure is a measure of force per area and is expressed in pascals (Pa). Density is mass per volume, and while kilograms per cubic meter is the SI unit, kilograms per cubic centimeter is also a valid density unit (it's 1000 kg/m^3). Distance is a length, commonly given in centimeters or meters. The matching given uses pressure with pascals, density with kilograms per cubic centimeter, and distance with centimeters, which are all correct and commonly used units in practice. The other options assign units that don’t fit the corresponding quantities, such as pressure with meters per second (a velocity), or distance with feet or kilometers in a way that disrupts the standard unit pairing.