Noise cancellation headphones have found a comfort zone among air travelers and music afficionados, but now they may also be finding a sweet spot as a piece of construction equipment.

Safety equipment manufacturer Elvex, Corp., Bethel, Conn., has begun marketing DeTune Communications Earmuffs, a construction version of the high-tech headsets speciallytuned to filter out  the high-impact noises common on construction sites, without interfering with normal conversation.

"It blocks sudden onset noise, like hammer blows and pile drivers in the mid frequencies," says Fred Ravetto, vice president of sales, who introduced the electronic muffs at a recent trade show in Las Vegas.

Two control knobs let users selectively filter out high and low frequencies independently. Another adjusts volume. The high filter allows filtering down to about 2,000 Hz and will eliminate about 85% of the frequencies within the adjustment range. The low frequency filter lets users filter out frequencies up to 600 Hz.

The impact filter works in addition to the other two, shutting off sound in a few microseconds and reactivating it in about two milliseconds, according to Ravetto. The quick recovery time makes it possible to converse, even in harsh construction environments.

The muffs come in two versions, one powered by AA size batteries which costs $74 and a deluxe, rechargeable version costing $115. See them at www.elvex.com.