Abstract: Sound is vibration. It can be the desired vibration of a musical instrument passing to the air and then to the listener’s ears. It can be the wanted vibration of a loudspeaker transducer. It can be the unwanted vibration of a loudspeaker cabinet passing to the floor or supporting surface, which then vibrates in sympathy, producing interfering and unwanted additional signal paths. These phenomena can be measured and assessed including the potential psychoacoustic impact of the additional signal paths. In this study, the author measured the sound and vibration produced by a floor-standing loudspeaker: Vibration induced into surfaces and sound produced in the air, with the loudspeaker mounted on either damped isolators or on solid wood blocks between the speaker cabinet and the floor. Analysis of the data reveals: .
• Vibration isolation under speakers produces measurable differences compared to wood blocks: more than 15 ms in reverberation time in some frequency ranges; low level artifacts in the waterfall; up to a dB in distortion in some ranges; up to a dB in frequency response.
• The type of shell construction affects isolation performance — specifically solid barriers vs. limp mass.
• In general, isolation produces an improvement in performance and potential audible benefits, minding the shell construction of the room.