On Sound Machines Posing a Hearing Risk

As a new mother who also happens to be an acoustician, the recent report of infant sleep machines being a hearing risk caught my attention.  How couldn’t it?  Not only did my mother-in-law send the article to me, but even my fellow acousticians were posting it and commenting about it via various social media platforms.  Aside from sensationalizing an issue that is clearly a case of extremes, the report (read the NY Times article here) brings up an important social topic in general: excessive sound.  This is becoming a hot topic, especially for those who work in architectural or environmental acoustics.  Not only can infant sound machines exceed OSHA limits, but so can the daily sounds that we adults expose ourselves to- headphones, traffic, movie theaters, cars or motorcycles with modified exhausts, concerts, bars and restaurants in which excessively loud atmospheres appear to be the trend these days, etc.  Except where intentional (motorcycle exhausts, e.g.), there are usually design flaws to blame.  This means that the problem could have been avoided, but in this business the acoustics of a design are almost never as important as the aesthetics. This is where an old saying takes on a new meaning: out of sight, out of mind.  Is it possible that  we rely so much on the visual that we’ve come to neglect the aural?  Do we, as a society, simply undervalue our ears and the gift of hearing? Back to the article for now, why use sleep machines?  Besides the obvious (more…)

Need to reach a certain IIC rating? Read this before you contact an acoustic consultant.

This is something that comes up every day in my line of work: IIC [and STC] ratings of floor-ceiling assemblies.  I get calls from homeowners, architects, contractors, developers, product distributors- pretty much anyone involved in flooring whether they’re on the design side, sales side, or construction side.  Almost always, it goes the same way: Customer: I need to reach IIC — (usually it’s a 50 to reach code minimum, but sometimes it’s a 60). Which underlayment should I use? This is where I try my hardest not to sound disinterested or condescending, because I really don’t feel that way- it just requires a conscious effort not to sound robotic when you’ve gotten used to asking the same questions.  Chances are, other acoustic consultants may have a similar experience, so here’s some sound advice to prepare yourself with before you contact an acoustic consultant. IIC and STC ratings are dependent on entire assemblies, not any single element. This means that you’ll need to have all of the details of your floor-ceiling assembly before you can expect real advice from an acoustician.  Ideally you’ll have an architectural drawing calling out each element and it’s thickness in the assembly, but if not, I usually email a list like this for them to fill out: – Floor Finish – Underlayment – Subfloor system (concrete slab?  wood joist?  truss?  spacings, thicknesses, gauges, etc.) – Batt insulation in the ceiling cavity? – Resilient channels? – Ceiling details (material, number of layers, thicknesses?) The science of predicting (more…)

Acoustic Engineer, Inventor, Entrepreneur Amar Bose Dead At 83

In a 2004 interview in Popular Science magazine, he said: “I would have been fired a hundred times at a company run by M.B.A.’s. But I never went into business to make money. I went into business so that I could do interesting things that hadn’t been done before.” A perfectionist and a devotee of classical music, Dr. Bose was disappointed by the inferior sound of a high-priced stereo system he purchased when he was an M.I.T. engineering student in the 1950s. His interest in acoustic engineering piqued, he realized that 80 percent of the sound experienced in a concert hall was indirect, meaning that it bounced off walls and ceilings before reaching the audience. … Dr. Bose made a lasting impression in the classroom as well as in his company. His popular course on acoustics was as much about life as about electronics, said Alan V. Oppenheim, an M.I.T. engineering professor and a longtime colleague. “He talked not only about acoustics but about philosophy, personal behavior, what is important in life. He was somebody with extraordinary standards,” Professor Oppenheim said.   Sharon Paley‘s insight: I recently watched Dr. Bose’s last lecture at MIT.  Looks like he would’ve been an awesome professor. (more…)