Noise from sonicators is best controlled using the manufacturer’s enclosures. If an enclosure is available its proper and intended use should be required. Barriers can be effective since high frequency sound is very directional. Efficient procedures that minimize exposure are also useful.

ACGIH TLVs (Threshold Limit Values) provide specific best practice guidance on ultrasound exposure in contrast to OSHA’s Hearing Conservation Standard. There are ceiling TLVs of 105 dB as well as 8-Hour TWA values for 10, 12.5, 16,20 kHz mid-frequency third-octave bands. Our sound level meter can measure these frequencies.

The TLV recognizes that:

“subjective annoyance and discomfort may occur in some individuals at levels between 75 and 105 dB for the frequencies from 10 kHz to 20 kHz especially if they are tonal in nature. Hearing protection or engineering controls may be needed to prevent subjective effects.”

What does this mean? People may detect and dislike sonicator noise but it is not a known health effect until 105 dB ceiling or 88-94 dB 8-h TWA (depending on frequency). Voluntary use of hearing protection (probably muffs for short duration and/or infrequent tasks) should be encouraged for those experiencing nuisance noise. But mandatory use of hearing protection should be reserved for those installations that met or exceed that TLV. Engineering controls based on manufacturer’s recommendations should be the primary control method.