In Memoriam: Renowned Yale Acoustical Engineer Robert E. Apfel

Robert E. Apfel, The Robert E. Higgin Professor of Mechanical Engineering at Yale, died on August 1 at age 59.

A Yale professor for over three decades, Apfel had been the chair of the former Council of Engineering, comprising the Departments of Chemical, Electrical, Mechanical Engineering and Applied Physics. He was also a visiting professor at the Yale School of Architecture. Apfel developed an interest in acoustics at Tufts University, where he graduated Magna cum Laude with a bachelor’s degree in 1964 and earned his Phi Beta Kappa pin. In his senior thesis project, he combined his love of music with science by studying the acoustics of an auditorium. He went on to earn a Ph.D. in applied physics at Harvard in 1970.

Apfel was a former president of the Acoustical Society of America (ASA) and the creator and editor of the new online journal Acoustics Research Letters Online (ARLO). In 2002, he received ASA’s highest honor, the Gold Medal for Lifetime achievement; he had published over 120 articles in 36 journals including 41 in the Journal of the Acoustical Society of America and was granted four patents.

Apfel was interested in the tensile strength of liquids. One of his studies in this area involved testing the tensile strength of micron-sized drops, whose small volumes could result statistically in a perfectly clean liquid. In performing this experiment, he had to develop techniques for “acoustic levitation,” a topic he greatly innovated and a term that he coined. One of his research articles in Nature found that many liquids could achieve their theoretical strengths.

Apfel discovered a unique method for deriving Einstein’s time dilation formulas. He will also be remembered for a paper titled “Whispering Waves in a Wine Glass,” in which he describes how a wine glass can “sing.” Two of his experiments were done on the shuttle Columbia twice in the 1990s. Although he taught in the Mechanical Engineering Department at Yale, he gave lectures in the School of Architecture and wrote a primer on architectural acoustics called “Deaf Architects and Blind Acousticians.” He edited his mentor, Ted Hunt’s book, “The Origins of Acoustics,” and worked together with Ted’s son, Tom to establish the Hunt Fellowship. Apfel’s many honors and achievements include the 1971 A.B. Wood Medal from the American Institute of Physics for his fundamental work on the properties of liquids; the ASA Biennial award (now the Lindsay Award) in 1976; and the ASA Silver Medal in Physical Acoustics in 1997.

Among the close to 50 students Apfel mentored at Yale, almost all have assumed major roles in ASA and in society in general. In 2002, he received the Yale Graduate Mentor Award and his former graduate students, in appreciation for his caring attention, established the Robert E. Apfel Fellowship Fund.

Apfel was a writer, poet and active member of the Unitarian Society of New Haven. He was also involved in the New Haven community, especially as a mentor for students in the New Haven school systems and with the New Haven Science Fair. In 1996, he received an Elm-Ivy Award in recognition of his efforts to strengthen the relationship between Yale and the City of New Haven.

Apfel is survived by his wife of 34 years, Nancy (Howe) Apfel, daughter, Alison Apfel of Brighton, MA, and son, Darren Apfel and daughter-in-law, Laurie Post Apfel of Redmond, WA. He is also survived by his brother, Rick Apfel, sister-in-law, Darlene Jones, and nieces, Gillian and Lauren Apfel. He was predeceased by his brother, Rod Apfel.

Donations to the Robert E. Apfel Fellowship Fund can be made to: c/o Dean of Engineering, Yale University, P.O. Box 208267, New Haven, CT 06520-8267.