Fundamental of Acoustics and Vibrations

A: Option A carries the full chain: hemispherical radiation introduces an 8 dB term and distance adds 20log10(1.5). Option B feels right if you're used to pressure-to-pressure scaling, but it drops the hemispherical reference baked into sound power relations. Option C is a classic lab-to-field slip where 1 m intuition overwrites the logarithmic definitions. Option D remembers the floor but forgets that pressure still decays with distance, which shows up fast once you're beyond 1 m.

A: Option A aligns with how many test houses mark sine excitation on drawings, even if reports later convert to RMS. Option B borrows habits from velocity-based standards and applies them to an unlabeled acceleration callout, which is where audits get messy. Option C sounds practical if you've spent time at a shaker, but peak-to-peak is almost always spelled out due to the 2× ambiguity. Option D mixes frequency-domain thinking into a time-domain symbol and leaves acceptance undefined.

A: Option A follows transmissibility theory: raising stiffness pushes the natural frequency up and can land it right on an engine order. Option B matches first instincts from static deflection thinking, but ignores dynamic amplification below isolation frequency. Option C assumes a clean frequency shift without acknowledging the mount-body coupling that still excites panels. Option D underplays structure-borne paths, which tend to own idle complaints.

A: Option A ties directly to sound power being a source property, not a room property. Option B confuses calibration physics with test setup geometry. Option C sounds attractive if you've chased bass, but the standard actually tries to avoid room gain. Option D mixes marketing goals with metrology, which ISO avoids on purpose.