The Inaudible Sounds of Science: Animals and Media from the Galton Whistle to Bat Echolocation

Abstract

Animals have long served as acoustic barometers for human listeners, marking the limits of the unheard. Since the 19th-century, scientists have suspected that nonhuman listeners could hear sounds too high-pitched to be registered by the unaided human ear. This dissertation suggests that animal figures are useful vectors for exploring an expanded history of sounds, including high-pitched liminal frequencies, in the scientific context. Furthermore, I show that the limits of human hearing, and the sensory thresholds that constrained the average listener’s experience, were highly debatable parameters well into the 1920s. By reframing high-frequency, inaudible sound as something other than a quantitatively stable category – one now earmarked for vibrations above twenty thousand cycles per second, called “ultrasound” – within historical materials, this project disrupts and dismantles the category itself. Although high-frequency inaudible sounds were indeed real vibrational materials, they also became imbued with social and cultural meanings through efforts of acoustic and electrical mediation. Inaudible sounds were always, in part, social constructs that reflected the ambitions, anxieties, and fears of their sociocultural and political milieus.

Tracing shifting relationships between sound-reproduction media, animal listeners, and scientific observers in the American and British contexts, “The Inaudible Sounds of Science and Medicine” considers various mediations of inaudible sounds from 1876 to 1950 – a period that encompassed changing ideas about what high-frequency inaudible sound vibrations meant. In the fin-de-siecle acoustic era, prior to the electrification of sound-reproduction media, animals served as important experimental subjects for establishing the perceptual limitations of humans. Scientists used insects, mice, bats, dogs, and other nonhuman listeners as markers for deciding on sounds that were too high-pitched for them to hear. For example, in 1876 psychometric practitioner Francis Galton strolled through zoological gardens, blowing his high-frequency whistle and watching animals prick their ears in response to the inaudible sounds. Between the years 1876 and 1924, I show that inaudible sounds were indexical of animal telepathies, supernatural senses, spiritual worlds, and stubbornly un-quantifiable vibratory matters. By the late 1920s, however, inaudible sounds became reconfigured through electrical sound-reproduction media – increasingly quantified and proceduralized through mediating instruments.

Although inaudible sounds were gradually excised from their fin-de-siecle occult contexts, their animal affiliations endured. Certainly, electroacoustic technologies became integral to quantifying and standardizing what would become ‘ultrasound’ and ‘infrasound’ – categories of sounds that existed beyond the audible spectrum. But sound-reproduction technologies capable of more automatically processing inaudible sounds hardly replaced animal listeners or human observers; they simply rearranged them – giving them new experimental roles to play. Bats and insects persisted as objects of scientific intrigue and value, appearing time and time again in front of microphones, radios, and piezoelectric transducers, as they fluttered around laboratory spaces and filled anechoic chambers with their unheard echoes. Even after scientists built sound-reproduction machines that could perceive what their own ears could not, they continued to recruit animal ears to participate in their experiments and to confront their own sensory limits.

Ambitious in scope, this dissertation positions inquiries into the nature and significance of inaudible sounds as a culturally pervasive one – cutting across multiple disciplinary boundaries such as medicine, psychology, physics, and electroacoustics. It explores a wide range of listening techniques and sound media, from whistles and phonographs to electrical stethoscopes, “ultra-audible” microphones, and Sonic Amplifiers that translated inaudible bat voices into audible beats.